Working on a stock 82 that been sitting for a long time. Had to replace gas tank & internals. Car starts and runs but none of the gauges or tach work. The lights work,
Any suggestions?

 

Unhook a terminal on battery. In front of firewall, the "box" with all the wires going into it near steering column. There is a bolt that holds that tight, take out the bolt. Clean all connections with a wire brush.Blow out residue. Goop it up with the clear anti corrosion gel. Reassemble.

If that doesn't do it, possibly a new circuit board(PIA).

 

Check the GAUGES fuse. Everything you mention (plus the key in/seatbelt/headlamps on signal) is on that fuse. If it's OK check for +12V at the pink with black stripe wire on the connector to the gauge pack with the ignition on. If you get power then the printed circuit for the gauge pack has probably delaminated with traces broken or shorted. In this instance the tach problem will be separate

 

Thanks for the replies.

The fuse block bulkhead has some nasty black gunk in it. I assume this something the factory puts in it. Gotta find something to cut that.

Gauge fuse was the first thing I checked but will check the circuit also. One thing I found was that the alternator was fried. Unlikely the gauge problem though. Will update when I find the problem.

Thanks
again.

 

Mike is right, the tach issue is a separate issue. But the gauges all power up on the pcb behind the center cluster so it's possible that the pcb is the problem for the gauges and in most cases that is the cause.

A quick way to test the gauges would in this fashion... on the oil pressure, temp and fuel gauges... pull the ohms wire from the sender and turn on the key... Then ground out the ohms wire attached to the sender and you should see the following.

Ohms wire not attached:
Oil pressure gauge should peg
Temp gauge should go to all the way cool.
Fuel gauge should peg full.

Ohms wire grounded
Oil pressure gauge should go to empty
Temp gauge should go to full hot
Fuel gauge should peg empty.

Go to our tech page listed below and it will give you more detail on how to test the gauges.

The black stuff between the connectors is normal but there are ways to test this without taking it apart.

If it were me I'd start at the center cluster, remove it and test the connector and inspect the pcb on the backside. If you go to this link you'll find how to remove the center cluster. Just start at the middle of page three. http://repairs.willcoxcorvette.com/w...stallation.pdf

If you do remove the cluster you can test each connection by using the picture below and you can also ping continuity from the connector the the end of the ohms wire.


If you want to test the tach, use this to help you.

http://repairs.willcoxcorvette.com/c...ink-1978-1982/

Willcox

https://willcoxcorvette.com/
http://repairs.willcoxcorvette.com/

 

The "black gunk" is dialectric grease that prevents oxidation. It's essentially ever-lasting. Definitely don't remove it--if anything add more.

 

 

Mine too! Everything worked in late June when I took it to a car show. Got it out two weeks ago to go to a club dinner and the gages and tack are dead, the headlight warning buzzer sounds all the time if the headlights are on with the car running. It's been in the shop all week and they can't find the problem yet.
Oh, I forgot to mention. The mechanic found a fuse blown, replaced it and took the car out for a test and it blew again. Plus, the radio display only works intermittently although the radio itself plays.

 

Check grounds and power then look for corrosion or burned connections on the circuit board and plug. This is where I find the most issues.

 

I'll share this with the shop that has my Vette. Thanks

 

Thanks for the help gunfighter13, but my mechanic found the problem this weekend and it wasn't in the dash at all. He found a wire in the engine compartment that somehow came loose from somewhere and ended up touching the exhaust manifold, burnt through insulation and shorted out intermittently whenever the Vette hit a bump. And, no, I don't have a picture or even a description of which wire it was which I realize will be of no help to anyone else who might have a similar problem in the future.

 

Glad it was an easy fix, that's why I said check Grounds followed by Power circuits and then the Circuit board. The small black wire that is bolted to the bell housing most likely. Let everyone know if he can explain which wire it was.

 

Awesome, that gives me another place to look at.

Thanks

 

OK, was able to test gauges using this method and here are my findings:

Gauge Reaction Ohms wire grounded Reaction ohms wire unhooked ohms across resistor
Gas went empty went full 34.8
oil press showed 0 went to 1/2 35.5
water temp no reaction no reaction 52.5
oil temp no reaction no reaction 91.3
volt could get any reaction 75

All other test have showed good
PCB tests good
getting power and ground to gauges
engine grounds good
circuits from senders to gauges good
Fuse is good

The owner says he used a 240 amp jump starter to try and start the car before he brought it to me. Is it possible this could have fried the gauges?

Thanks

 

Replaced gauges with salvage units and they are now working.
Removed tach and performed test and all looked good. Reinstalled tach and is now working, wasn't making good connection I suppose.

Thanks for everyone's help.