No Tach

[Marccus]

I removed my dashboard to replace my blower motor actuator. When I reinstalled the dash, my tach doesn't work.

When the key is in the start position, the tach needle rises up a hair or so and stays there, and then drops when the engine is turned off. The speedo works.


How does the tach work? Is it electronic, unlike the speedo which has the speedo cable that runs to the transmission? What "wires" or connections are involved in runnning the tach?

I thought I reattached the two large connectors on the instrument panel correctly as I have removed the instrument panel before to clean it to replace all the bulbs. I did notice some of the copper traces lifting from the plastic mounting sheet where the connector is inserted.

Also, as I was cutting away the messy gummy adhesive tape to on the engine wiring harness and replace it with self-fusing silicone tape and wrap the un-wrapped wires. But I think I cut a black wire as I found a cut wire when I peeled away the old tape. :headbang:

I say "I think", because I was careful when cutting and maybe it was this way before. I re-connected the two ends of the wire. This black wire runs to the large connector on the ignition on the steering column. There seemed to be too much slack in the wire as I had to wrap it back and forth on the wiring harness with the other wires in the bundle --

--- perhaps I pulled the wire out of some connection on the other end?

Is it possible that this wire has something to do with the tach not working or is it most likely unrelated?

Any help / suggestions appreciated.

 

[Bizzy]

The tach is electrically operated. It consists of one coil connected between the battery and ignition coil and receives voltage pulses from the ignition coil when the engine is running.

In the 91 vehicles the tach is connected to the instrument cluster via pin 7 on a tan/yellow stripe wire. This goes into a connector, then into a gray/orange stripe wire. There is a splice in the line where one end goes to the tach service connector (passenger side near strut tower) and the other goes on to the ignition system (EEC and IRCM). Both wires are gray/orange stripe wires. And again, this is on the 91.

I would think that your problems would be in the area you worked in (inside the car) rather than outside, but you may want to check to see if any stretching caused an issue with where the wires are spliced. Double check your connectors, make sure they are clean, tight and that the wires are firmly attached where they enter the connector.

Retrace your steps, as painful as it may seem, even consider dropping the dash back down to double check your work.

Good luck!

 

[Marccus]

Thanks for the informative response. My car is an '89 with 293,000 miles.
Sounds like a wire problem and I'll have to dig out my wiring diagrams.

I don't want to drop the dash again.
Please, Lord, not again. :cry: :cry:

It took my 14 hours to drop and re-install it after I discovred that that I was sent the wrong part for the blend door actuator motor.