Where to pick up Tachometer signal in cabin?

[stevenlee]

I'm installing a new security system that requires a tachometer signal. The instructions recommend tapping into one of the coil packs. I am hoping to find a tach signal in the cabin to avoid the long run to the engine bay.
Does any one know where I can pick up a tachometer signal in the cabin?

 

[shawn110975]

what year is your NSX?

I think you can tap into a wire coming from the ECM behind the seats

let me look it up for you.

here it is from the manual

" Tachometer
With the Ignition in on (II) or Start (III),
the tachometer drive circuit in the gauge assembly
receives pulses from the engine control module (ECM).
The ECM determines the engine speed from the crankshaft
postion/cylinder postion (CKP/CYP) sensor.
The number of pulses per minute is directly proportional to
the engine speed. The tachometer drive circuit controls the tachomter. "

let me know what year you NSX is as the color of wires change a little from year to year.

 

[stevenlee]

Shawn thanks for your reply. It is a 1994. I'm hoping to pick up a wire close to the dash. If needed I will make a connection to the AEM ECU.

 

[shawn110975]

when I get home today will look it up for you

 

[stevenlee]

Sahwn, Were you able to find a source for tachometer signal in the cabin near the dash?
Does anyone else know where I can pick up a tach signal under the dash for an alarm install)?

 

[shawn110975]

sorry I totally forgot. will try today. must be the A.D.D.
or its new name A.D.H.D lol

next year it will be called Q23-ADGHN

these Quack Doctors.

 

[I1O101I]

Sahwn, Were you able to find a source for tachometer signal in the cabin near the dash?
Does anyone else know where I can pick up a tach signal under the dash for an alarm install)?

http://www.the12volt.com/installbay/alarmdetail/165.html

Hope that helps

Bryan

 

[stevenlee]

Bryan,

Thanks for the link. It identifies the tach test connector in the engine bay as the source for the tach input. I know that the wire goes into the cabin and am looking for a place to pick up the tach without having to run a wire through the firewall. I could probably find it behind the passenger's seat at the ECU but I'm hoping to find a source near the dash.

 

[FastraxTurbo]

You can pick up a tach signal from the PCM-pinC8, Cruise control unit-pin 6, or gauge cluster-pin B11

 

[stevenlee]

Fastrax... Eureka!!! Thanks a Million.

 

[angus]

Actually you can get it from the blue wire in the harness that goes up to the instrument cluster.

 

[stevenlee]

Thanks Will. I think you might be familiar with the alarm system I'm installing. It has remote start. So I guess I will use the blue wire unless you or someone else tells me it won't work with the alarm system.

Hope to meet you at NSXPO.

 

[angus]

Thanks Will. I think you might be familiar with the alarm system I'm installing. It has remote start. So I guess I will use the blue wire unless you or someone else tells me it won't work with the alarm system.

Hope to meet you at NSXPO.

You need the blue wire, the ecu signal wire is different. It's a blue wire with little silver bands on it sometimes, it is the same wire at the test connector in the engine bay.

 

[stevenlee]

You need the blue wire, the ecu signal wire is different. It's a blue wire with little silver bands on it sometimes, it is the same wire at the test connector in the engine bay.

Wil, I haven't been able to find that blue tach wire. The service manual wiring diagram shows a green wire going to the tach. I looked at the tach wire in the engine bay and it looks green. Is the correct tach wire on the B connector on the right side of the gauge cluster. I can't find a diagram of that connector to verify the wire functions.

Where is the best place to pick up that tach wire? Do you know which connector and/or pin? Is it shown anywhere in the service manual?

 

[angus]

Wil, I haven't been able to find that blue tach wire. The service manual wiring diagram shows a green wire going to the tach. I looked at the tach wire in the engine bay and it looks green. Is the correct tach wire on the B connector on the right side of the gauge cluster. I can't find a diagram of that connector to verify the wire functions.

Where is the best place to pick up that tach wire? Do you know which connector and/or pin? Is it shown anywhere in the service manual?

Super easy way to verify the tach signal, put your multimeter on A/C volts then test the wire, if it's correct, the voltage increases as you rev the car up.

 

[FastraxTurbo]

Did you even read my post? Gauge cluster-B11. Should be the connector on the left side. Looks like a green wire.

 

[stevenlee]

Fastrax, I read your post but couldn't figure out what wire is B-11. I couldn't find a diagram of that connector in the service manual.

Wil, thank you for teaching me how to test for the right wire.

(I've got to board a plane now and will be testing the wires next week.)

 

[99 rs]

Your question already got answered but for future reference here is the list below taken from the12volt.com like the guy a few posts above. If you go there and click the "vehicle wiring" under NSX then the 1999 version of the wiring says it's the green wire by the cluster.

Constant 12V+ White or White/Black Ignition Switch Harness
Starter Black/White Ignition Switch Harness
Ignition Black/Yellow Ignition Switch Harness
Accessory Yellow Ignition Switch Harness
Tach Green Left of Column Green Connector going to Cluster
Brake Switch Green/White Brake Switch
Trunk Release White/Black Switch
Trunk Pin Blue/Silver (-) Anti-Theft Module below Glove Compartment
Parking Lights Red/Black Driver's Dash at Gray Connector
Head Lamp Blue/Red Anti-Theft Module below Glove Compartment
Factory Disarm Green/Red (-) Door Locks
Door Trigger Green/Blue DR. Green/Red Module below Glove Compartment Isolate
Door Lock Green/White (-) In Driver's Door
Door Unlock White/Yellow (-)
Horn Wire Green/White (-) Anti-Theft Module below Glove Compartment
Windows Up LF=Red/Blue, RF=Blue/Yellow
Windows Down LF=Red/Yellow, RF=Blue/Green