[Mook]

In my 69 GTO, last night I noticed my factory temp gauge climbing while I was driving. When I slowed down it went down. The needle seemed to bounce even when I turned. (strange) So of course I thought there was a coolant flow issue. So I had a new high performance stat sitting around so I figured I would give it a shot. Now in normal driving conditions my gauge would hang around halfway and with the a/c on the temp rose to just a little above halfway. After the stat change I noticed that the gauge at idle hung around the upper(lower temp) mark. Wow I thought the performance stat really worked!!?

But when I turned my lights on the needle on the gauge began to climb to around half again? Each time I turn off the lights the temp would read cooler and each time I cut the light on the temp gauge would rise!!! Has anybody experience anything like this?

The more I think about my car the more I think there is a ground or electrical issue. My radio works fine until I use the RCA inputs. The music will blank out on acceleration especially when the car is cold, it also blanks out when I use my turn signal. If I turn on the lights or rear defog or even the a/c or heat the radio RCA's work fine. Any ideas????

Thanks Guys...........

["QUICK-SILVER"]

Temperature the only guage acting up, no problem with gas or oil?
If not, it's sounding like a WEAK ground on the temp guage only.
Do the dash light dimmer up and down and see if temp guage responds.

Stereo sounds like lose connection, quitting on take off. Turn deal is something else, any power wires on turn signal circuit?

Don't know where it's at but probably wouldn't hurt to check the MAIN ground junction under the dash.

[Mook]

Thanks, I will l look for the main ground.........

I just checked the lights again and the oil gauge reacts also to the light coming on and going off........

the radio does have a wire for the lights that is hooked one of the wires on the harness that is connected to the dimmer so it comes on with the dimmer........

Question......the ground for the gauges look like little flat piece of metal with oval holes on each end?

If so I think I left at least one off.....I found it in a pile of screws and stuff!

I don't have a "real" ground strap running from the block to the firewall. It's a 10 or 12 gauge piece of wire.......maybe I need to find a true ground strap?

Thanks

["QUICK-SILVER"]

Nothing wrong with the 10 or 12 guage wire from block to firewall. A couple of 10's would be better.

Metal strip probably was a ground strap but sounds like something that would've been used around the wiper switch.

Cluster ground is a wire or two in the plug-in for the rest of the instrument cluster. Might be able to wiggle the cluster plug-in and see if it's a bad connection.

[Mook]

Originally Posted by "QUICK-SILVER"

Temperature the only guage acting up, no problem with gas or oil?
If not, it's sounding like a WEAK ground on the temp guage only.
Do the dash light dimmer up and down and see if temp guage responds.

Stereo sounds like lose connection, quitting on take off. Turn deal is something else, any power wires on turn signal circuit?

Don't know where it's at but probably wouldn't hurt to check the MAIN ground junction under the dash.

QUICK-SILVER.......the gauges do respond when I turn the dimmer up and down. When it is down the gauges seems to be closer to the accurate reading. If the car is off and I rurn on the parking lights the temp gauge is buried past the 250* mark and the oil gauge goes all the way up...is this normal?

Could my head light/dimmer switch be bad?

Thanks

["QUICK-SILVER"]

Originally Posted by Mook

QUICK-SILVER.......the gauges do respond when I turn the dimmer up and down. When it is down the gauges seems to be closer to the accurate reading. If the car is off and I rurn on the parking lights the temp gauge is buried past the 250* mark and the oil gauge goes all the way up...is this normal?

Could my head light/dimmer switch be bad?

Thanks

Turning the dash light dimmer and making the guages move is typical when you have a bad ground to the instrument cluster.

Head light dimmer switch doesn't have anything to do with the guage problem. Although, if high beam indicator is in the instrument cluster, it could have some effect on the guages, same as dash lights.

If you can get to the back of the cluster, you can add a ground wire for a quick/permanent fix. There's should be grounded screws holding down the printed circuit. The flat wire will be visible where the screw goes through the printed circuit right into the metal in the back of the cluster. A wire from there to something solid should take care of it.

[Mook]

Originally Posted by "QUICK-SILVER"

Turning the dash light dimmer and making the guages move is typical when you have a bad ground to the instrument cluster.

Head light dimmer switch doesn't have anything to do with the guage problem. Although, if high beam indicator is in the instrument cluster, it could have some effect on the guages, same as dash lights.

If you can get to the back of the cluster, you can add a ground wire for a quick/permanent fix. There's should be grounded screws holding down the printed circuit. The flat wire will be visible where the screw goes through the printed circuit right into the metal in the back of the cluster. A wire from there to something solid should take care of it.

Well I added the ground as you suggested, so far it seems to be working and my lights within the cluster are brighter to-boot! It seems to have fixed my other problem with the radio cutting out when I use the RCA inputs while the car is running, I figure since the radio has a light that is connected to the dimmer, grounding the cluster might have made the difference....... :-), thanks so much QUICK-SILVER