I have an 83 Z28 with a wiring problem. When I adjust the gauge cluster lights my instruments (battery, oil, temp) go to zero when the gauge lights are lit. As I move the rheostat around when the gauge lighting goes out the cluster begins to work again. The other problem is when I turn on the right signal the gauges "bounce" with the blinking. If I remove one of the right turn signal bulbs are removed (and the blink doesn't blink)...then the gauges do not bounce. The right turn signal lamp still lights up (the one with the bulb still in it ). Any ideas?

It sounds as if the car wiring has been hacked. The dimmer rheostat should not effect the gauges.

Try this test...at the fuse block remove the gauge fuse, which should be a 15A fuse. Pulling this fuse should kill power to the gauges. Now start the car and adjust the rheostat. If the gauges still misbehave the +12volt wiring has been modified and the light circuit is now powering the gauges.

Let us know the results of this test so we can figure out what to look at next.

This is a very common ground problem. You'll need to find the black wires that supply ground to the instrument cluster and clean the terminal that's attached to the body. Insufficient grounding will cause backfeeding of the circuits in the cluster (gauges, illumination, indicator lamps) which manifest itself in fluctuating gauges. The ground in question is G200, it is located behind the instrument cluster, in the dash.

Hope this helps.
Lou

Thanks for the suggestions...I will try both. Can you provide further info about the G200 business. Knowing the nomenclature (G200) would probably be very useful if I could get little more education. When I look behind the instrument cluster there is an abundance of wiring back there...a bit intimidating. But I'm game.

If you have not done so yet, get a 9/32 inch socket and nut driver and remove the trim piece just below and centered on the steering wheel. Four screws hold it in. After you remove this, look just to the left of the steering column. You will see a silver colored (in 82 anyway) nut with two black wires under it. That is the G200 ground point. It is bolted to a steel piece that supports that side of the instrument cluster.

Nice pictures. GOO JOB, DAVE!
You know what they say: a picture is worth a thousand words. It sure fits well in this thread.
I am bookmarking it right now and will reference it in future answers to instrument cluster grounding problems.


Lou

Lou

Thanks for the compliment.

The the pictures tell quite a bit. I wrote the description and realized that it would not help those who were unfamiliar with the maze of wires under the instrument panel.

One item the pictures do not show is if there is a nut on the other side. For the 82 Camaros, there is no bolt. It is just a screw into the framework. I assume the same will be true for later model years. So you only need to pull the small piece of trim out to get to the G200 screw.




jumpnjoe59

Try Lou's suggestion to check the condition of the G200 ground point first. There will be a lot less work involved with that approach. If you look closely at the close up photo of the connection you can see a bit of rust on the steel framework. If you see rust under the wire lugs or the screw is loose, take it apart, clean it and put it back together.

It would require quite a bit of work on your part to trace out circuits if they have been modified....So let's not go down that path unless we have to

Let us know what you find.

My problems are similar. Intermentent lights but not all and voltage, never a tach or oil pressure..both peg high. I removed the cluster, inspected and all looks good, cleaned the contacts, checked the G200 ground and cleand it.
Now I have one light and no voltage indication and still no change in the tac and oilpressure.
I am like the original poster..out of ideas to check.

Did you check the dimmer control to make sure it is still good?

How old are the cluster lights? Have you ever replaced them? They might be burned out. If you pull the cluster again, make sure that the light sockets are in firm contact with the light trace circuit on the cluster panel. You might also want to try a continuity test between each light socket to verify that the trace is not cracked or broken.

For the tach, have you searched this thread for past posts. A few years back there were a few good threads concerning tachs that did not work. Note that there were two different solutions, based on the year of your car. Have you verifed the tach wire out to the coil, it could be open or shorted, causing your problem. The tack filter could also be in need or replacement.

For the oil pressure guage, have you verified that the oil pressure sending unit is working correctly. The guage itself could be broken.

I could not tell from your post if you are having problems with you voltage guage and coolant temperature guage. Again have you verified the wiring from the sensor all the way to the guage? These guage(s) could also be bad.

If you are having problems with all four guages not reading correctly, have you verified that the GUAGE FUSE is not blown or missing, or loose in the fuse block?

For the gorund connection to G200, did you do a continuity check on that wire all teh way back to the connector blocks for the clusted? If not, you might want to check that as you could have a good connection at G200 and a bad connection where the cluster plugs into its connectors, or a bad wire in between.

If the ground is ok then you likey have two or more porblems. The first is the lights, and then the guages.

Dave