Tachometer Failed

[Gordie]

After a fuel stop my tachometer failed. Any suggestions?

 

[dalybo]

the tach electrical circuit is interconnected with several other gauges such as the oil pressure and coolant temp gauges...so do these gauges work properly or not?

 

[Gordie]

All other gauges are working fine.

 

[Jin1976]

Tachometer as in speedometer? If that's the case you may want to replace the Vehicle Speed Sensor. Cheap replacement. :smile:

 

[Gordie]

Tachometer as in speedometer? If that's the case you may want to replace the Vehicle Speed Sensor. Cheap replacement. :smile:

No, a Tachometer, or rev. counter in old English, shows engine speed and in the NSX and most modern cars is driven by a pulse signal from the ECU.

My original comment was written to see if failure like this is a common NSX problem and is it more likely to be a gauge or gauge driver problem. If it is the Tacho driver, mounted on the gauge circuit board then do I need to remove and replace panel B of the gauge assembly circuit board? Since other gauges on that part of the circuit board work, I am assuming it is not a blown fuse.

 

[Hugh]

Quoting from the ETM:
"The tachometer drive circuit receives pulses from the engine control module (ECM). The ECM determines the engine speed from the crankshaft position/cylinder position (CKP/CYP) sensor. The number of pulses per minute is directly proportional to the engine speed. The tachometer drive circuit controls the tachometer."

So it could either be a bad CKP/CYP sensor, bad tach unit or an open connection somewhere in the circuit. The first thing I'd check is the connector from the CKP/CYP sensor. It is connector C146, gray in color with 8 wires. It is located towards the back and to the right of the alternator underneath the cover.

If you're not getting a CEL then it could be a poor connection and not the sensor itself which would be a bitch to replace since you have to pull the timing belt to get at it.

 

[Larry Bastanza]

A bad CKP/CYP sensor would be throwing codes. Do you have a check engine light on?

LarryB

 

[Gordie]

A bad CKP/CYP sensor would be throwing codes. Do you have a check engine light on?

LarryB

No engine check light so my guess now is a loose connection, a bad tacho driver or the gauge itself.

Thanks for the reply.

 

[Gordie]

Quoting from the ETM:
"The tachometer drive circuit receives pulses from the engine control module (ECM). The ECM determines the engine speed from the crankshaft position/cylinder position (CKP/CYP) sensor. The number of pulses per minute is directly proportional to the engine speed. The tachometer drive circuit controls the tachometer."

So it could either be a bad CKP/CYP sensor, bad tach unit or an open connection somewhere in the circuit. The first thing I'd check is the connector from the CKP/CYP sensor. It is connector C146, gray in color with 8 wires. It is located towards the back and to the right of the alternator underneath the cover.

If you're not getting a CEL then it could be a poor connection and not the sensor itself which would be a bitch to replace since you have to pull the timing belt to get at it.

Thanks for your comment. I have no Check Engine light and so I am assuming the pulse signal is good. We will check for other loose connections then check the tacho and driver on the panel circuit board.

Thanks.

 

[smoore]

check the harness area behind the passanger side seat. You rev gauge cable goes in over there maybe something just came loose. move some of the harness around that area see if you get the gauage working again

 

[Gordie]

We have determined that the fault is in the instrument circuit board,tacho or tacho driver.
Can any one help sorce a replacement. - See my new thread ( Tachometer, Oddometer Circuit Board)