• Protip: Profile posts are public! Use Conversations to message other members privately. Everyone can see the content of a profile post.

93 NSX. Click, No Crank, No Fuel Pump Prime

Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
Hello Guys
1993 NSX, Manual Trans, 114k

Click, No Crank, No Fuel Pump Prime

I have replaced the following using OEM parts from Japan.
  • Main Relay
  • Power Relay
  • TCS Safe Relay
  • Fuel Resistor Relay

I put the key in the ignition, turn it to the "on" position....
(1). Check Engine Light illuminates briefly as it should with the key in the “ON” position and then turns off.
(2). I can hear the Main Relay 'click' as it should.
(3). I cannot hear the fuel pump prime.
(4). Starter does not crank.

* I attached a 'cable with a manual push button' to the starter and the starter cranks and turns the engine over, but still will not start, even with the key in the 'on' position. During the first month this worked to start the car, but no longer does at all.

* I have openned the ignition switch to check it and to clean it. Everything inside looked fine. I am ordering a new ignition switch on Monday.

* Healthy Yellow Top Optima Battery

I read every thread on this topic, several times. I have been trying to get my NSX to start for over 6 months following everything I read as a guide. I also replaced all the relays above (one at a time, then tried to start before installing the next relay). I was sure one of the four relays would solve my issue, however, still no success. I am finally making this post. Please help. Thanks
 
Last edited:
Rating - 0%
0   0   0
Joined
Nov 3, 2011
Messages
2,889
Location
Saskatchewan, Canada
A rather unusual set of circumstances, particularly since the starter motor system and the fuel pump system are pretty independent of one another. I am wondering whether you have two independent problems rather than a common failure

Two things
- your signature says you have had the 1993 since 2012 so I assume there are no hidden surprises such as a security system with immobilizer relays in the fuel and starter circuits.
- get a copy of the service manual because I have a feeling that you are going to need the wiring diagrams.

First, start with the starter motor circuit since it is pretty simple.

You know the starter motor works. If the ignition switch is working and you don't have an aftermarket immobilizer the most common problem would be a missing clutch interlock switch stopper which is disabling the starter cut relay. The starter cut relay could also have failed or you could have a loose connection broken wire someplace. After insuring the stopper is in place I would start with the starter cut relay because you can test to make sure that it is getting +12v on the blk/wht wire when you turn the ignition switch to start and you can jumper from the blk/wht wire to the blk/blu wire which should cause the starter motor to engage when you switch to start. Based upon those test results you should be able to figure out where the problem is located by studying the diagram. The nasty bit is that the starter cut relay is well hidden in the center stack area so you need to remove the glove box and I think the right side of the center console to get access. Even with that stuff removed its its a knuckle scraper to get at the relay.


Starter circuit.JPG

The main EFI relay is a two in one relay which includes the relay which controls the fuel pump. If you installed a new main relay then presumably both of the relays inside the case are functioning. The circuit is not super complex.

Main FI relay 2.JPG

Since the ECU is powering up (CEL comes on) the ECU should be providing a ground signal to the fuel pump portion of the main relay to prime the pump. You need two people for this next test. Go to the fuel pump resistor location in the engine compartment. Physically inspect to make sure that the heat from the resistor has not damaged the wiring. Disconnect the resistor and test it to make sure that it has not failed as an open circuit. If the resistor and wiring is good, reconnect it and back probe the blk/red wire on the resistor plug so that you can measure the voltage relative to a good chassis ground. Connect a voltmeter or 12 v test light there. Have someone switch the ignition to run. You should hear the main relay click and you should measure 12 v for about 2 - 3 seconds which is the fuel pump prime pulse. If you get 12v for about 2-3 seconds and the pump does not run, the pump is dead or you have a wiring problem between the resistor and the pump. If you do not get the 2 second 12v pulse at the resistor location you need to work your way back to the main relay to confirm that the fuel pump portion of the main relay is operating (check for 12 v pulse on blk/yel wire at relay).

The fuel pump control relay coil is connected to ground by the ECU to operate it. You can simulate this ground connection by back probing the grn/blk wire at the main relay plug and jumpering it to ground. With the ignition switched on this this should force the pump to run. If the pump runs there is a problem with the connection from the relay to the ECU or the fuel pump control transistor in the ECU has failed.

I have done screen grabs from a 1991 service manual for the schematics. They should be correct; but, Honda may have made revisions to wire colors which is why it would be best to have the correct service manual for your 1993.
 
Last edited:
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
Wow. Thank you for this detailed reply. That was thoughtful. You certainly know what your way around an NSX. I appreciate your time Sir. I will follow your advice and update when I have learned more.

*I should have mentioned prior that my 93 NSX came with a Viper Alarm already installed when I bought the car. I hate aftermarket alarm systems, as they can cause problems. I am wondering if this is the issue and suspect it might well be. I will work towards removing this alarm system.
 
Rating - 0%
0   0   0
Joined
Nov 3, 2011
Messages
2,889
Location
Saskatchewan, Canada
*I should have mentioned prior that my 93 NSX came with a Viper Alarm already installed when I bought the car. I hate aftermarket alarm systems, as they can cause problems. I am wondering if this is the issue and suspect it might well be. I will work towards removing this alarm system.

That is an important detail and I would start there since it would be really unusual for two relatively isolated systems like the fuel pump and starter circuit to fail simultaneously. If you can find the Viper module I would be inclined to just unplug it and see if that allows you to get the car started. The normal practice is to wire up the interposing immobilizer relays in a fail-safe mode so that if the relay(s) fails you are still able to operate the car. Unplugging the viper should disable the relays and might allow you to start the car. However, there is no guarantee that it is wired that way. If you had the original Viper instructions and installation manual that might give you some clues as to how it is interconnected with the NSX body wiring.

Some of the aftermarket systems integrate with the factory NSX security module which may make it more difficult to diagnose what is going on. In early NSX cars that are not equipped with the immobilizer key the factory security system only blocks the starter motor circuit, not the ECU or fuel pump (later cars kill both the starter and the ECU). Look for some extra relay on the inside back firewall that might be blocking the fuel pump circuit.
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
Once again, great advice. I will do as you have suggested. I found a PDF online of the Viper wiring instructions and manual. I will first unplug the Viper alarm system and see what happens. I will update what happens when time permits. Thanks for your help so far!
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
A rather unusual set of circumstances, particularly since the starter motor system and the fuel pump system are pretty independent of one another. I am wondering whether you have two independent problems rather than a common failure

Two things
- your signature says you have had the 1993 since 2012 so I assume there are no hidden surprises such as a security system with immobilizer relays in the fuel and starter circuits.
- get a copy of the service manual because I have a feeling that you are going to need the wiring diagrams.

First, start with the starter motor circuit since it is pretty simple.

You know the starter motor works. If the ignition switch is working and you don't have an aftermarket immobilizer the most common problem would be a missing clutch interlock switch stopper which is disabling the starter cut relay. The starter cut relay could also have failed or you could have a loose connection broken wire someplace. After insuring the stopper is in place I would start with the starter cut relay because you can test to make sure that it is getting +12v on the blk/wht wire when you turn the ignition switch to start and you can jumper from the blk/wht wire to the blk/blu wire which should cause the starter motor to engage when you switch to start. Based upon those test results you should be able to figure out where the problem is located by studying the diagram. The nasty bit is that the starter cut relay is well hidden in the center stack area so you need to remove the glove box and I think the right side of the center console to get access. Even with that stuff removed its its a knuckle scraper to get at the relay.


View attachment 174869

The main EFI relay is a two in one relay which includes the relay which controls the fuel pump. If you installed a new main relay then presumably both of the relays inside the case are functioning. The circuit is not super complex.

View attachment 174870

Since the ECU is powering up (CEL comes on) the ECU should be providing a ground signal to the fuel pump portion of the main relay to prime the pump. You need two people for this next test. Go to the fuel pump resistor location in the engine compartment. Physically inspect to make sure that the heat from the resistor has not damaged the wiring. Disconnect the resistor and test it to make sure that it has not failed as an open circuit. If the resistor and wiring is good, reconnect it and back probe the blk/red wire on the resistor plug so that you can measure the voltage relative to a good chassis ground. Connect a voltmeter or 12 v test light there. Have someone switch the ignition to run. You should hear the main relay click and you should measure 12 v for about 2 - 3 seconds which is the fuel pump prime pulse. If you get 12v for about 2-3 seconds and the pump does not run, the pump is dead or you have a wiring problem between the resistor and the pump. If you do not get the 2 second 12v pulse at the resistor location you need to work your way back to the main relay to confirm that the fuel pump portion of the main relay is operating (check for 12 v pulse on blk/yel wire at relay).

The fuel pump control relay coil is connected to ground by the ECU to operate it. You can simulate this ground connection by back probing the grn/blk wire at the main relay plug and jumpering it to ground. With the ignition switched on this this should force the pump to run. If the pump runs there is a problem with the connection from the relay to the ECU or the fuel pump control transistor in the ECU has failed.

I have done screen grabs from a 1991 service manual for the schematics. They should be correct; but, Honda may have made revisions to wire colors which is why it would be best to have the correct service manual for your 1993.
Okay. I spent last weekend thoroughly going over the car. I removed the entire interior, seats, carpets, firewall panels, removed the entire center console, radio and climate control unit, the dash is almost out.

I've inspected most of the interior wiring carefully, especially at the interior firewall, but I want the dash out to do my final inspection.

I disconnected the aftermarket Viper alarm. It was installed rather simply, via stripping back a small amount of rubber coating off the factory wires, with an aftermarket wire wound around the exposed factory wiring, then wrapped in electrical tape. (No oem wires were cut, no solder used either, no butt connectors). Once the dash is out I will clean this up back to original. Note: Under the dash, I did find 2 aftermarket relays, both within 6 inches of the Viper alarm brain, one has wires running across to the glove box area, it appears to be connected to the factory alarm system. The other relay has wires running up to some plug directly above the clutch interlock switch stopper. I hope that makes sense. Both these aftermarket relays were connected to the oem wiring as I described at the top of this paragraph. Nothing was cut, just wire spun on to the existing oem wiring harness.

Car still will not crank, no fuel pump prime.

I am going to perform your detailed test recommendations after the dash is out, and after the clutch interlock switch stopper has been tested or replaced, and after the starter cut off relay has been tested or replaced.

I found the clutch interlock switch stopper. It appears to look just fine and operational, but I don't know how to test it.

I have not found the starter cut relay yet. I will look again tonight. I removed the glovebox, the bose subwoofer and the carpet. I can basically see everything while laying upside-down, but I am not sure what the starter cut off relay looks like. Can you provide a part# so I can order one and have a photo to compare it with. I've searched all over the internet for this part# but no luck yet.
 
Last edited:
Rating - 0%
0   0   0
Joined
Nov 3, 2011
Messages
2,889
Location
Saskatchewan, Canada
Here is a picture of the starter cut relay location.

starter cut relay.jpg

My recollection is that you can see the SCU and door lock control unit with just the glovebox removed; but, I don't think you can see the cut relay because it is a couple of inches higher than the SCU or the lock unit. I think you need to remove the right side of the center console to get eyes on the thing.. It has been several years since I had to go poking around in there.

The parts manuals do not list a starter cut relay. They just list 'power relay' and let you guess. On my 2000, I believe the relay is 39797-SE0-003 (might be rev 004). However, I think the relay changed during production. I would be inclined to wait until you have the relay 'in hand'. If it is a Denso (likely) it will have a Denso part number on it and you may be able to source it for a much lower cost using the Denso part number in Google search.
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
Thank you Sir. I found the starter cut relay / power relay behind the passenger airbag. I have relocated it somewhere more sensible. That is truly the dumbest place to put such an important relay.

Starter Cut Relay part # is Denso 056700-8570
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
Do you know someone I can send my ECU to inorder to test it?

If an ECU were bad, do you know anyone who can repair it and reflash it?

I called Science of Speed today and they do not test or repair ECU's
 
Rating - 0%
0   0   0
Joined
Nov 3, 2011
Messages
2,889
Location
Saskatchewan, Canada
Thank you Sir. I found the starter cut relay / power relay behind the passenger airbag. I have relocated it somewhere more sensible. That is truly the dumbest place to put such an important relay.

Starter Cut Relay part # is Denso 056700-8570
The starter cut relay is probably made inaccessible to thwart car thieves. In pre immobilizer key equipped cars, the cut relay is the primary anti theft device that prevents the thief from driving away in the car. If the relay was easy to get to it would be easy to by-pass.
 
Rating - 0%
0   0   0
Joined
Jul 27, 2007
Messages
6,114
Location
Denver, CO
An ECU failure is extremely rare. Before you start messing with the ECU, I would run all of the service manual tests on the components that could be affecting the starter. Namely the ignition switch, clutch interlock, starter cut relay, main relay.

You should trace the circuits with a multi-meter to make sure you don't have an open in one of the wires. And, run all of the current tests on the components to make sure they are working properly.

#1 cause of this is the clutch pedal stopper
#2 cause is a bad main relay
#3 is a bad ignition switch (either bad contacts or damaged wires from a crappy stereo/alarm install)

Since you have an aftermarket alarm, that means someone probably hacked up your ignition switch wires with T-taps or splices. I'd look at the switch/wires and test it.
 
Rating - 0%
0   0   0
Joined
Nov 3, 2011
Messages
2,889
Location
Saskatchewan, Canada
Do you know someone I can send my ECU to inorder to test it?

If an ECU were bad, do you know anyone who can repair it and reflash it?

I called Science of Speed today and they do not test or repair ECU's
Have you actually tested the external components to the point that you believe the ECU is a problem, or are you trying to preemptively eliminate it as a possibility by external testing to confirm that it is OK? If the second approach is what you are doing, I wouldn't for the following reasons:
- Honcho is correct that this is an extremely low failure rate item
- Unnecessarily un plugging and reconnecting multi pin plugs can create new problems (loose internal terminals or snapping of the plastic retaining clips). Those plugs were never designed for frequent use. Don't remove it without being fairly certain the ECU is the problem or you need to test the external ECU circuits.
- The NSX is a bit of an orphan. It is unlikely that any commercial services will have the firmware to reload into the controller if the firmware is corrupted. I doubt that the controller chip for ECU is still in production. Most of the commercial services are about repairing the I/O circuits or the power supplies. Everything else takes too long to diagnose and repair for them to make money at it.

You indicated yesterday that you still have not been able to get the starter motor to operate. The starter motor control circuit is 100% isolated from the ECU controls. Figure out what is disabling the starter motor circuit and get it working. Whatever is disabling the starter motor circuit may also be disabling the fuel pump control. Right now it seems like you are taking a parts cannon approach.
 
Rating - 0%
0   0   0
Joined
Sep 28, 2004
Messages
154
Location
Temple Terrace FL
You mentioned that you found a Viper alarm in your car. I had one installed in my car for many years and it worked well until it did not. The alarm worked well but after a few years my car would not crank. I replaced the ignition switch a few times, cleaned and eventually replaced the starter. I completely removed the Viper system and I have not had a problem since. Jerry
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
The starter cut relay is probably made inaccessible to thwart car thieves. In pre immobilizer key equipped cars, the cut relay is the primary anti theft device that prevents the thief from driving away in the car. If the relay was easy to get to it would be easy to by-pass.
I agree with you 100%. I was wrong, a bit frustrated. I will put it back to factory. I have ordered a new Denso starter cut relay.
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
An ECU failure is extremely rare. Before you start messing with the ECU, I would run all of the service manual tests on the components that could be affecting the starter. Namely the ignition switch, clutch interlock, starter cut relay, main relay.

You should trace the circuits with a multi-meter to make sure you don't have an open in one of the wires. And, run all of the current tests on the components to make sure they are working properly.

#1 cause of this is the clutch pedal stopper
#2 cause is a bad main relay
#3 is a bad ignition switch (either bad contacts or damaged wires from a crappy stereo/alarm install)

Since you have an aftermarket alarm, that means someone probably hacked up your ignition switch wires with T-taps or splices. I'd look at the switch/wires and test it.
Thank you for your input and wisdom, Honcho. I appreciate both you and "Old Guy's" wisdom. I will carefully follow the advice you both have given.

I am relieved to learn the ECU rarely fails. That's what I wanted to hear.

Wednesday night I completely removed the Viper aftermarket alarm and all the wiring & relays associated with it.

I have already installed OEM...
  • Main Relay
  • Power Relay
  • TCS Safe Relay
  • Fuel Resistor Relay
I have ordered an...
OEM Ignition Switch.
OEM Starter Cut Relay.
Clutch Pedal Stopper.
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
You mentioned that you found a Viper alarm in your car. I had one installed in my car for many years and it worked well until it did not. The alarm worked well but after a few years my car would not crank. I replaced the ignition switch a few times, cleaned and eventually replaced the starter. I completely removed the Viper system and I have not had a problem since. Jerry
Thank you Jerry for your encouraging mention. As of Wednesday evening, I have removed the entirety of the Viper Alarm. I will attempt to start the car in a few days after everything oem is plugged back in.
 
Last edited:
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
Have you actually tested the external components to the point that you believe the ECU is a problem, or are you trying to preemptively eliminate it as a possibility by external testing to confirm that it is OK? If the second approach is what you are doing, I wouldn't for the following reasons:
- Honcho is correct that this is an extremely low failure rate item
- Unnecessarily un plugging and reconnecting multi pin plugs can create new problems (loose internal terminals or snapping of the plastic retaining clips). Those plugs were never designed for frequent use. Don't remove it without being fairly certain the ECU is the problem or you need to test the external ECU circuits.
- The NSX is a bit of an orphan. It is unlikely that any commercial services will have the firmware to reload into the controller if the firmware is corrupted. I doubt that the controller chip for ECU is still in production. Most of the commercial services are about repairing the I/O circuits or the power supplies. Everything else takes too long to diagnose and repair for them to make money at it.

You indicated yesterday that you still have not been able to get the starter motor to operate. The starter motor control circuit is 100% isolated from the ECU controls. Figure out what is disabling the starter motor circuit and get it working. Whatever is disabling the starter motor circuit may also be disabling the fuel pump control. Right now it seems like you are taking a parts cannon approach.
I was just trying to preemptively eliminate the ECU as an issue. I figured if I had to send it to someone I better get a headstart just in case. I am happy to learn from you and Honcho that it rarely fails. I greatly appreciate you taking the time to explain the intricacies of the ECU.

Yes, admittedly, I have taken a "parts cannon approach", lol. The reason for such is because I wanted all the parts on hand just in case I needed them in the future. And after everything I have read, all the parts I have ordered each are common faults for the NSX. Once I solve the issue I will put the extra parts in the trunk in case an issue arises in the future.

I will do exactly as you and Honcho have advised. Thanks for your patience with me so far and for your time!
 
Rating - 0%
0   0   0
Joined
Nov 3, 2011
Messages
2,889
Location
Saskatchewan, Canada
Edit - go to the very last paragraph and read the red text first. If you have an OEM security system problem you might want to skip all of the stuff below.

If you got to the point of having the dash out, don't put it back yet. With the wiring harness exposed, diagnosis of the starter circuit problems will be easier. This is the starter motor circuit from the NSX Electrical Trouble Shooting Manual.

ETS Starter Circuit.jpg

Its functionally the same as the previous diagram I provided from the service manual; but, it also shows all the connectors (marked with a C) and important details such as
- the starter circuit running through the under dash fuse box
- and there is a connector (C102) buried under the relay / fuse box in the engine compartment .

First, make sure that fuse 29 is OK. You can functionally check that by measuring the voltage to chassis ground on the wht/red wire (body wiring harness side of C446 at the ignition switch). You should have 12 volts. If you don't have 12 volts the fuse is likely blown which could explain a lot of the problems - then you need to figure out why it is blown.

If fuse #29 is OK then carry out the following. Using the continuity function on a multimeter or some other continuity tester, start with C446 (ignition switch connector) and check for continuity to C455 (the plug on the starter cut relay). Then check continuity on
C455 to C405
C522 to C103 (that is a long reach and you will probably need to add a wire extension on your tester)

I suggest that you test directly from C522 directly to C103 on the starter. Getting to C102 requires disconnecting the engine compartment fuse box to get access to C102 which is a fair amount of effort. Only do that if you get an open circuit between C522 and C103.

If you find an open circuit between any two connectors you may have found the location of an aftermarket interposing interlock relay.

If all those connections are intact and your ignition switch, cut relay and starter motor are OK then the starter motor pretty much has to crank when you turn the key and press down on the clutch. When you press down on the clutch, listen for the click of the starter cut relay. If there is no click then remove the cut relay from the socket and connect a jumper from the blk/wht wire to the blk/blu wire which should completely by-pass the starter cut relay / security system functions. Try the starter motor again. If it now operates the problem is in the cut relay control circuit which includes the clutch interlock switch and the factory security control unit - a whole new place to start looking. You didn't mention it; but, by any chance has the vehicle security system stopped operating (you can't arm the system). If the security system does not operate correctly that might be the system to start checking for problems first and that problem may be caused by your Viper wiring.
 
Rating - 0%
0   0   0
Joined
Jul 27, 2007
Messages
6,114
Location
Denver, CO
If you find an open circuit between any two connectors you may have found the location of an aftermarket interposing interlock relay.
I hadn't thought of that, but good point. The alarm installer might have put in a second interlock/cut relay somewhere on the starter circuit. It's worth checking.

I also agree with Old Guy that you should test all of the wires in the circuit diagram for continuity- it's possible you have an open somewhere, especially since you mentioned the alarm installer stripped the OEM wire insulation to install his taps/splices. But first, I agree you should check the fuse and test the starter cut relay to see if it clicks.
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
Edit - go to the very last paragraph and read the red text first. If you have an OEM security system problem you might want to skip all of the stuff below.

If you got to the point of having the dash out, don't put it back yet. With the wiring harness exposed, diagnosis of the starter circuit problems will be easier. This is the starter motor circuit from the NSX Electrical Trouble Shooting Manual.

View attachment 174966

Its functionally the same as the previous diagram I provided from the service manual; but, it also shows all the connectors (marked with a C) and important details such as
- the starter circuit running through the under dash fuse box
- and there is a connector (C102) buried under the relay / fuse box in the engine compartment .

First, make sure that fuse 29 is OK. You can functionally check that by measuring the voltage to chassis ground on the wht/red wire (body wiring harness side of C446 at the ignition switch). You should have 12 volts. If you don't have 12 volts the fuse is likely blown which could explain a lot of the problems - then you need to figure out why it is blown.

If fuse #29 is OK then carry out the following. Using the continuity function on a multimeter or some other continuity tester, start with C446 (ignition switch connector) and check for continuity to C455 (the plug on the starter cut relay). Then check continuity on
C455 to C405
C522 to C103 (that is a long reach and you will probably need to add a wire extension on your tester)

I suggest that you test directly from C522 directly to C103 on the starter. Getting to C102 requires disconnecting the engine compartment fuse box to get access to C102 which is a fair amount of effort. Only do that if you get an open circuit between C522 and C103.

If you find an open circuit between any two connectors you may have found the location of an aftermarket interposing interlock relay.

If all those connections are intact and your ignition switch, cut relay and starter motor are OK then the starter motor pretty much has to crank when you turn the key and press down on the clutch. When you press down on the clutch, listen for the click of the starter cut relay. If there is no click then remove the cut relay from the socket and connect a jumper from the blk/wht wire to the blk/blu wire which should completely by-pass the starter cut relay / security system functions. Try the starter motor again. If it now operates the problem is in the cut relay control circuit which includes the clutch interlock switch and the factory security control unit - a whole new place to start looking. You didn't mention it; but, by any chance has the vehicle security system stopped operating (you can't arm the system). If the security system does not operate correctly that might be the system to start checking for problems first and that problem may be caused by your Viper wiring.
Ok. I first checked fuse 29 under the hood. It was not blown.

I twice checked all the fuses under the hood, under the dash, and in the engine bay. Not a single fuse was blown.

*I cannot find my continuity/voltage tester, so I need to go buy one soon. Once I get the tester, I'll follow your other recommendations.

I could Not hear the starter cut relay click, so I held it in my hand as pushed down on the clutch and turned the key, I could not even feel anything resembling a click. I tried this about 5x. While these tests were going on over and over, I could hear the main relay behind me clicking so loudly it made it hard to hear if the starter cut relay clicked. I could also hear a couple other relays clicking. This was all distracting from focusing on the starter cut relay, hence holding it to feel for a click. I will have a friend come tomorrow and push the clutch and turn the key while I put my ear on the relay.

So next, I removed the starter cut relay and jumped the blk/wht wire with the blk/blu wire. Still nothing! I tried this 3x. There are 2 blk/wht wires side-by-side, so I switched to the other blk/wht wire and jumped it with the blk/blu wire. Still nothing, but a spark. I used alligator clips with protective rubber coatings.

The Viper Alarm worked just fine, locked & unlocked the doors, and the alarm would go off if I tried to open the doors while locked. Arm & Disarm worked fine.

I have now removed the Viper Alarm, and all of its wiring & relays have been removed.

When I purchased this 93 NSX, I never received the OEM security alarm transponders to arm or disarm.

Not sure what this indicates....
The red blinking anti-theft light (next to the driverside door lock) would blink when armed, when the Viper Alarm was installed. But now that the car is back to the OEM security system, it longer blinks, even if I lock the car with the key, or press the door lock while still inside the car, it no longer blinks. I remember my 1991 NSX also did not come with the OEM transponders, but the security light would come on when I locked the door via the key.

The fuel pump still does not prime.

The starter only cranks if I attach a handheld push button starter.

Hopefully when I get the new ignition switch tomorrow, perhaps it will solve the problem.
 
Last edited:
Rating - 0%
0   0   0
Joined
Nov 3, 2011
Messages
2,889
Location
Saskatchewan, Canada
The NSX does not have any security system transponders. Unless the car was equipped with the accessory keyless entry it is armed by locking the doors. Even if it had the keyless entry system, locking the doors with the key should still set the alarm. If you lock the doors and the arm indication LED on the driver side door no longer blinks, that indicates that the security system may not be functioning; but, make sure that all the doors, hood, trunk are latched because that will block arming. It might be good to check that the OEM security module is still installed in the car and plugged in. You can see the security module in that photo in post #7. As an observation, if the OEM security system is not arming that would normally allow you to start the car just by pressing the clutch in.

However, the operation / non operation of the factory security system may be a secondary consideration. When you connected a jumper from the blk/wht wire to the blk/blu wire in the starter cut relay socket (it doesn't matter which blk/wht wire you used), you completely by-passed the clutch interlock and the factory security system. As you can see from the diagram below, with the red jumper in place you should have a direct connection from the ignition switch to the starter solenoid and you should be able to get the starter to turn..

Starter circuit _ 2_LI.jpg

Start with the continuity tester checking from the ignition switch to the cut relay, the cut relay to the fuse panel and the fuse panel to the starter solenoid. If you can't find an open circuit, double check by doing voltage measurements. Back probe the blk/wht wire in C466 to measure the voltage relative to the chassis. Turn the key to start and you should get 12 volts. If you don't, there is something wrong with the ignition switch or the wiring up-stream of the ignition switch. If you get 12 volts at the ignition switch then work your way down through the circuit testing for voltage by turning the key to start.
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
Will do! Thank you so much for your detailed help and your time.
 
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
The oem security module is still installed.

My car did infact come with an oem accessory keyless entry system. I found the module. But I do not have the transponders.

And per my prior post stating the LED door alarm light not coming on. You identified the reason why, I now realize I had both the hood & the trunk open, hence why it would not arm the factory alarm.
 

Attachments

  • Screenshot_20221013-161140_Gallery.jpg
    Screenshot_20221013-161140_Gallery.jpg
    123.4 KB · Views: 6
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
When you connected a jumper from the blk/wht wire to the blk/blu wire in the starter cut relay socket (it doesn't matter which blk/wht wire you used), you completely by-passed the clutch interlock and the factory security system. As you can see from the diagram below, with the red jumper in place you should have a direct connection from the ignition switch to the starter solenoid and you should be able to get the starter to turn..
Ok, I have a good update for once.

I made another jumper wire and went back to the Starter Cut Relay. I then jumped the blk/blu wire with the blk/wht wire. This time the starter cranked over!

I purchased a new Denso Starter Cut Relay and installed it, but the starter once again would not engage with this new part.

So that leads me back to the Clutch Interlock Switch or the factory security system. I will install a new Clutch Interlock Switch on Sunday.

In the photo below....
Is the Clutch Interlock Switch labeled as 'A' or the 'B' ? I'm thinking it is labeled 'A'
 

Attachments

  • Screenshot_20221015-233515_Gallery.jpg
    Screenshot_20221015-233515_Gallery.jpg
    176.6 KB · Views: 4
Last edited:
Rating - 0%
0   0   0
Joined
Oct 10, 2004
Messages
65
Location
Oklahoma
The Fuel Pump still does not prime.

The fuel pump resistor in the engine bay is OEM & new. The Main Relay is OEM & new.

I connected my continuity tester directly to the Red/Blk wire at the fuel pump connector, and turned the key to start. This caused the continuity tester to show some numbers for the first 2 seconds, but it quickly zeros out before I can see the voltage.

I inspected the wires carefully at the fuel pump resistor and do not see any evidence of heat damage.

I won't have anyone available until Sunday evening who can help me turn the ignition on while I test the fuel pump resistor wires in the engine bay.

I want to unplug the fuel pump connector plug at the rear firewall and run 12V directly to the fuel pump to see if it will run briefly. Do I run power to the blk/red wire and connect - to the blk/silver wire?
 
Last edited:
Top