What is the tach signal???

[meet07]

I check pin number 7 at the ECU yesterday and it read 11.9 volts. Is that the signal or does it change when the accel pedal is pressed??

[Darius]

The signal out to the tach should be a 0-5V signal not 12V. There is something wrong there. Are you sure it is the right wire? The FSM says it should be approximately 1.0 V at idle and 2.4 V at 2500 rpm.

[meet07]

There must be something wrong b/c thats the wire that I checked. I want to say that it is a yellow and blue wire. I figured that I would check it at the ecu rather than the plug

where does the signal at the ecu come from....??? The cas??

[Darius]

Yes the wire is Y/L.

Yes the signal comes from the CAS, but it is converted by the ECU into a voltage (0-5V).

[meet07]

hmmmm ok. I guess that I will mess with it some more. The y/l wire comes in from the ecu to the plug.......then goes through the plug to the middle connection behind the gauge cluster correct??? I noticed that my mph speedometer was bouncing a lil bit when my car was hunting the otherday