1991 ABS and Tr

[KraftwerkTurbo]

1991 NSX 5 spd
Anti Lock and TCS light are on.
Is assume (from other cars) bad ABS sensor or corroded/bad connection in wires/connectors from wheel to computer.
If that is the case, is there a way (code reader, else) to determine WHICH corner is causing the issue?

If that is NOT a typical issue caused by corrosion or bad wheel speed sensor, what else is a common cause?

Troubleshooting tips?

https://www.dropbox.com/s/ufawfxy1aa13t6b/IMG_20181026_125406.jpg?dl=0

 

[Old Guy]

No code reader required or available. The only code reader you need is a paper clip. Use the service check connector to retrieve the error codes stored in the ABS and / or TCS. You will need the service manual in order to interpret the codes; however, you might find the codes listed in the Prime Wiki. The codes will give you an idea as to what is up and should indicate which wheel is the problem if it is a wheel speed sensor problem.

 

[KraftwerkTurbo]

No code reader required or available. The only code reader you need is a paper clip. Use the service check connector to retrieve the error codes stored in the ABS and / or TCS.

Even so there is no check engine light on?
I found instructions (from paper clip to interpreting the flashes) and will try to read the stored codes. Some source say only the last 3 codes are stored, others say many more can be stored. Will see.


Counting the Flashes
To retrieve trouble codes, turn the ignition key to the “on” position with the engine off. 86-89 models: The ECU will flash many short blinks. The total number of blinks equals the code number. For example, 12 short blinks equals code 12, nine short blinks equals code 9, etc.. If more than one code is stored, the ECU will flash the codes in sequence (lowest to highest) with a pause between each code. The codes will repeat until the key is turned to the OFF position. 90-94 models: The ECU will flash a long blink to represent the first digit of the code, then a series of short blinks to represent the second digit. For example, 1 long blink, followed by 4 short blinks equals code 14. Four long blinks followed by five short blinks equals code 45.

Cearing Codes
On NSX models, remove clock fuse from main relay box, located in luggage compartment on RH side, for approximately 10 seconds to clear all DTCs. This will also cancel radio presets and clock setting.

 

[KraftwerkTurbo]

or this procedure:

[h=3]Accessing[/h]

• Ensure ignition switched OFF.
• Jump service check connector terminals [1] [3].
• Switch ignition ON.
• Check MIL is flashing.
• Trouble codes 1-9 are indicated as follows:

o Individual short flashes display trouble code [2] [A].
o A short pause separates each flash [2] .
o A long pause separates each trouble code [2] [C].
o For example: Trouble code 3 displayed [2].
​

• Trouble codes greater than 9 are indicated as follows:

o Long flashes indicate the ‘tens’ of the trouble code [3] [A].
o Short flashes indicate the ‘units’ of the trouble code [3] (C].
o A short pause separates each flash [3] .
o A long pause separates each trouble code [3] [D].
o For example: Trouble code 12 displayed [3].
​

• Count MIL flashes and compare with trouble code table.
• Switch ignition OFF.
• Remove jump lead.

[h=3]Erasing[/h]

• After the faults have been rectified, erase the trouble codes as follows:
• Switch ignition OFF.
• Remove clock fuse No.33 (7.5A) from underhood fusebox for 10 seconds minimum [4].
• Reinstall fuse.
• Repeat checking procedure to ensure no data remains in ECM fault memory.

 

[KraftwerkTurbo]

Even so there is no check engine light on?

Or does the paper clip in the service connector also lets the ABS and or TCS light blink the codes?

http://www.nsxprime.com/forums/attachment.php?attachmentid=74925&stc=1&d=1298758380

 

[Old Guy]

I have never had an error code triggered on my NSX, so I have no direct experience. I also have an OBD II car so I don't need to use the service check connector if I want to retrieve data from the ECU.

On the pre OBD II cars, the service check connector triggers the error code reporting for the ECU, ABS, TCS and the EPS if you have it. If you have multiple problems, I presume that they would all start blinking at the same time. You don't need to have the MIL light lit up to retrieve ABS error codes. However, some TCS errors can trigger errors for the ECU so watch for the MIL to start blinking if you have TCS errors. There can be stored codes in the ECU even without the MIL constantly lit up.

This is the procedure for retrieving the codes:

1. 
   [*=1]Ensure ignition switched OFF.
   [*=1]Short the service check connector terminals together (leave short in place).
   [*=1]Switch ignition ON (do not start engine).
   [*=1]Count the flashes on the ABS light (and /or the TCS light, MIL light EPS light).
   [*=1]To restart the error code reporting sequence, turn the key to off and then back to on and the ABS light will start running through the error codes again.

Yes, the ABS only stores 3 error codes.

The erasing procedure is as you describe, except pull the #32 ALB fuse to erase the ABS error codes.

The 1991 ABS system does not use short and long flashes. All the flashes are the same length. The delay between flashes separates the numbers

switch key on
- 2 second delay before first number starts flashing, count flashes
- 1 second delay before 2nd number starts flashing, count flashes
- this would give you the first error code. 4 flashes then 2 flashes would be 42
- 5 second delay before 3rd and 4th number start flashing. This gives you 2nd error code.
- another 5 second delay before 5th and 6th numbers start flashing.
- at end of the error codes you need to switch off and then switch the key back on to restart the error code reporting.

I hate doing the count the flashy light thing. I find its easier if you have someone trigger the SC connector and write down the codes while a separate person watches the light and calls out the numbers.

Here are the ALB error codes

View attachment 156574

 

[KraftwerkTurbo]

Update: when codes appeared, car was parked outside (40 degree F) for a few hours.
Back in garage for a day, started car: no more codes.

Does this indicate that ABS solenoids are getting lazy? Car is pampered (no rain), hate to take it to a gravel road to 'exercise' ABS. What is an easier alternative? I assume the solenoids run on 5 Volt? Or 12 Volt?

 

[KraftwerkTurbo]

In warm garage, did some work on the car (AC system now working again).
In light of the ABS and TCS lights on, also flushed the brake system (main reservoir on master cylinder), and sucked out old fluid from the small (clutch) and ABS pump reservoir. All new fluid is ATE brake fluid.
Took car out and lights came right back on.

The ABS pump does NOT seem to come on, as is often described as a symptom of 'sticky solenoid'.

Before doing the pump flush and solenoid 'exercise' (started looking into getting the harness and special T bleeder tool; but hate to spend the money if my issue is not related to those): what other troubleshooting/test should I do to narrow down what is causing the 2 lights to come on?

 

[Kaz-kzukNA1]

Read the error codes for both the ABS and TCS using the paper clip method at the blue 2pin SCS connector at the passenger footwell.

ABS code will only be repeated for a short period so if timed out, just switch Off and On the IGSW to repeat the process.

Leaky/sticky ABS solenoid issue won't trigger the TCS light.

Unless you have disconnected the battery, pulled out the specific fuse, pulled out the connectors from the controller or removed the metal rack behind the glove box (ABS controller uses case GND through this rack), the error codes are kept inside the ABS/TCS controllers even when you no longer see the warning lights.

So, first thing first, please read the code.


Kaz

 

[KraftwerkTurbo]

Will do that first thing. Last time I did, there lights were off and I did not see any blinking ABS/TCS lights. I assume the codes went away.

Also (just to be sure): will check fuse #32 (IIRC, for ABS pump).
Is there also a relay for the pump? If so, location?

 

[Kaz-kzukNA1]

From time to time, I heard owners trying to read the error code using the paper clip method but couldn't get good continuity and failed.

Good way of checking is to look at the CEL (Check Engine Light, MIL, engine silhouette).
If the CEL didn't stay On permanently (no engine error code stored) or didn't keep blinking (certain engine error code stored) and switched itself Off after 2sec from IGSW On, then you were not in the SCS mode.

May be you don't have the workshop manual???
You can download it through the NSX Wiki at the top of this page.

Presuming it's the LHD model, the pump relay is here, same location as the pump fuse inside the pentagonal/octagonal relay box under the bonnet.
These are for the pump side and not the system power.

Please note that when the ABS light is On, all ABS functions except for the w/speed signal conversion for the TCS are disabled including the ABS pump operation.
Not sure why you asked though….
Flushing the ABS or ABS pump related issue won't fix/trigger the TCS light.

Hope it's just simple w/speed sensor failure and not sensor signal noise issue that the calssic ABS brain can't detect unitl it gets really bad.


Kaz

 

[KraftwerkTurbo]

Thanks Kaz!
I have the manual (pdf scans) but it is difficult to navigate since it has not been digitized, so no search function.
Will the 'code' (hate that blinking stuff, never had good look using it on other cars) tell if the issue issue pump, solenoid or wheel speed sensor related?
Would pump/solenoid trigger BOTH dash lights (TCS and ABS)? Note: I have not observed the pump to kick in at all (as reported by those dealing with stuck solenoids, where the pump appears to be running TOO MUCH)?

I have NOT looked into troubleshooting/testing the wheels speed sensors at all. On newer cars, I had PLENTY of ABS/TCS codes from corroded wheel speed connectors (at the wheel hub), and some from corroded/dirty sensors; and a few where the tone ring was damaged.

 

[britlude]

abs AND tcs suggest it's a wheel sensor fault... but the code will tell you...

the abs light will flash a code, and the tcs light will flash a code (long flashes and short flashes).. from this we can get the fault status and which corner is giving the fault.

the flashing light thing is simple but effective