ARGH! Why won't my tach reset to ZERO after each start? It seems to keep 500 or so rpms.

[azmusclecar]

I have had my gauges apart oh say five times so far. Good news I got the oil pressure gauge to work and installed new LED lights.........BUT
I followed a repair video on the GBody You tube and I soldered a wire between the center post and the V8 post on the tach leads.
with the initail reinsertion of the gauges I turn the key to ON and the tach needle jumps to sero. I start the car and the tach reads maybe
1000 rpms on a fast idle. Yabba Dabba DO.........

NOW IS WHERE THE PROBLEM STARTS


When I shut the car off, the tach will stay at say 500-600 rpms. I turn the key back to start and it stays at it's previous read 500 or 600 and DOES NOT go back to zero.

When I start the car again the car's tach's reading goes up from there. So while idling at say 800 rpms (ThX Everyday Performance) the tach now reads 1200 or 1300.
Shut the car off, tach goes back maybe to 800. Then next start, it now goes to maybe 1500 instead of being at 800.

Any ideas as to WHY it does this? And I am trying to keep the gauge cluster working and in tack, or is that in TACH? Yes factory gauges
suck and blah blah blah but I'd like to know a real fix rather than opinions of factory gauges. Could the needle be sticking? IS there a
resistor that may be going bad?

 

[Ribbedroof]

What was the soldering attempting to repair?

 

[azmusclecar]

What was the soldering attempting to repair?

If you look at the setup there was a plastic clip with a piece of metal bent on it and in the video, the guy who produced the
video showed how over time, the plastic dries out and breaks and then the tach does not work.

So, there is a center point or post and then a post above the center post for V6 and the bottom is for V8

If you solder a wire between the center and for me the bottom post, the current can flow to get the tach to be able to read.

He used copper wire as did I. The entire video shows you how to repair dead gauges and refresh the cluster putting new
tension on the electrical points that lose their connectivity after time. The circuit board is a real work of GM art.....(sarcasm).

Here's the link to the video..........if you care to watch.............go to 14:32 on the video to see what I am telling you............

you tube video gauge cluster repair gbodys at DuckDuckGo

DuckDuckGo. Privacy, Simplified.

duckduckgo.com

 

[69hurstolds]

Hmm...got me stumped.

 

[Ribbedroof]

I always use a butane soldering iron on electronics, I don't like putting current through components, especially OLD ones.

Sounds similar to the Pontiac tachs. I wonder if a jumper from a HDD would do the trick without soldering?

I have to admit, I didn't watch the video, my laptop hates youtube, TV does OK, though.

 

[azmusclecar]

Just by clicking the key off and on the tach moves up about 100 rpms each time........it will not come back to zero.

 

[buick7332]

My Pontiac tach had the same symptoms as yours. I also removed the jumper bar and soldered in a piece of 14 copper wire and the problem was solved. I have not had any problems since.

 

[azmusclecar]

My Pontiac tach had the same symptoms as yours. I also removed the jumper bar and soldered in a piece of 14 copper wire and the problem was solved. I have not had any problems since.

I take it you mean 14 gauge copper wire...I just need to be clear............I will try anything now........

 

[buick7332]

I take it you mean 14 gauge copper wire...I just need to be clear............I will try anything now........

Yes, 14 gauge copper wire. I'm sure 12 gauge will also work

 

[azmusclecar]

I'll give it a shot tomorrow............thanks again for some direct info on how to fix.