My tachometer has been giving me some trouble. It hardly ever works, and when it does, it never goes about 1K rpm, even when I rev it high. Every once and a while, it'll work correctly for a few seconds. There is a white wire (green stripe) that is the signal wire coming from the ECU....but I was wondering...what engine sensor does the ECU get a reading from to signal the tach?

 

Its probably your guage messed up. Get a Doner Gauge set from a Junk Yard, pull your dash apart, put both gauge kits togehter on the bench and switch the new tach to your guage set. Should work perfectly after that.

-matt

 

I would bet money that the gauge is just out of wack. My friends max does the same thing...on his VAFC it says the right rpm but his gauge doesnt...signals from both come from the ECU...this means that the discrepency on the gauge comes from the gauge itself...i hope that made sense....im tired.

 

no, you made sense. It's just that I had the little tach unit out the other night and was looking it over....everything looks normal. There is one thing that I am unsure about though. There seems to be a little dial on the one side...maybe a potentiometer or variable resistor of some sort. I left it alone. Maybe I'll take it back out and move it and see what happens. The left reading says 2, and the right reading says 5...and you can move it anywhere in between. I thought maybe that it was used to calibrate it to the correct engine speed. It's not too big of a deal, it's just broken and annoying...especially when the needle bounces around all over the place.

 

Yeah, i would play with it to see what it does...its on your gauge cluster right...because I didnt see a dial on mine but I really wasnt really looking for it. Take a pic of it if you can.

 

Same problem here, apparently this is common. I took my cluster apart about a year ago, and didn't solve anything. Can the tach actually be removed from the rest of it? I thought it was all just one big circuit board on the back.

 

The tachometer is regulated by a signal from the ECM (ECCS control module) to cluster for the Tach. In my car ( 95 SE ) it's the White/Green wire on the Tach side and ECM side. The Factory service manual doesn't give me any info on how to check the Tach or I would have listed it for you. Maybe the info I gave you might help.

 

Crank Position Sensor (POS) -> ECU -> Tachometer.

 

haha, thanks. That's what I was originally looking for, since I figured maybe the sensor had a loose wire or something, but I guess according to everyone else, it's my tach itself that is f'd.

To answer a question that was posted previously...YES, the tach can be removed from the cluster. The circuit board "paper" that is on the back of the cluster is attached to the tach using the screws that hold it to the plastic backing. Screws are metal, so therefore can be used to supply the tach with the +, -, and signal to operate. It's quite a good idea actually. The screws serve two purposes.

To answer another question, the adjustment **** is on the tach circuit board itself. It's very small, and is light blue in color. It also has a philips style groove in the face of the **** for adjustment, since its so small.

One other thing....why does the VQ30DE have 2 crank position sensors? I was looking through the FSM, and found that it has not one, but two. I was talking to some electrical engineers/auto enthusiasts today, and they had no idea why. One sensor is on the passenger side of the engine, and the other sensor is on the driver's side.