78VettePlus

I have a problem as a result of some work I have done and it is a disappointing day now
I bought this 78 only 3 weeks ago and all gauges and instruments were working. The clock was not working. I removed the cluster, fitted a new quartz movement to the clock and reinstalled - no problems, everything working. (Well - amendment - turning on the headlights would make the temp gauge peg out - I think that was a poor connection on the plug to the board - It was slightly loose when I took the panel out today)
I noticed the fuel gauge was bouncing and assumed it was the sender, so I had it done at a shop, new sender. Still bouncing so I did some research and got a new gauge and printed circuit from Corvette Central.
The gauge was an AC Delco part and I checked it was internally set for resistance, so delete the external resistor.
Today I removed the cluster, carefully disassembled the rear and replaced the fuel gauge, reassembled with NO resistor over the fuel gauge, new printed circuit, and all other connections exactly as they were.
Re-installed the panel in the car and noted the following
Temp gauge, clock, and gauge lights working correctly
Fuel, Oil pressure and Volts NOT working
Generator warning light comes on and stays on
Seatbelt warning light does not come on
Tach not working - stuck at 1500

I located a blown 10 amp fuse in the 'Gauges" circuit and replaced that.

Reconnected the battery and no blown fuses

I have tried replacing the resistor, and the old circuit board in case I have a bad connection or it needed the resistor, but I have run out of ideas now

Any help or similar experiences would be appreciated. I don't have an ohm meter so cant do a bunch of tests on the sending units. I think I have a single dumb problem that I cant see. The gauges were all working last night, and the tach. It is something I have done today

bpassmore

Check the ground circuit for the gauges, with the gauges acting up with lights on indicate a ground fault.

78VettePlus

I agree. I don't remember disconnecting a ground wire from the instruments on the actual panel. I am assuming the ground is thru the plug connection?
The only other connection was the light at the top of the panel, to illuminate the heater controls.

78VettePlus

Further info;
When I changed out the old fuel gauge to the new gauge, I transferred the paper cylinder from the body of the old gauge to the new gauge (exact same size), and I removed the ceramic resistor. There were no plastic spacers or instructions in the box. I have read on this forum of another member who had problems and then found he needed to put a spacer in place of the resistor (and he did not get it in his kit)
I tried using a thick cardboard spacer in place of the resistor but no change, so I took it out
CC told me there is NO NEED for spacers OR the ceramic resistor with their gauge.

78VettePlus

OK I found a diagram showing the inst panel ground here
http://www.corvetteforum.net/c3/tune.../index19.shtml

will go check it.

78VettePlus

Well, there are a lot more wires than I expected, but nothing like that ground wire screwed to the frame, that I could see. I traced the main loom out from the fusebox, but could not find the ground wire.