Recently removed dash from my 68 to refinish and switch some of the gauges.Put in new headlight switch,ignition switch and put back together. Now the puzzle.No dash lights,only mechanical gauges work, headlights work,no tail lights or marker light. The horn wont work but the signals work. Radio also works. When I got the car the dash lights didnt work but tail lights did. I put everything back the same way I took it apart. I replaced the small fuse and others look fine.As far as grounding. the speedo/tach panel have 2 grounds that are in place but see nothing for the center gauge panel. I assume there are multiple issues but have no clue where to start. Any ideas? Thanks Paul Live in the greater Cincinnati area but haven't been able to find a tech to help= No one likes to deal with electrical stuff- this is my 14th Corvette and I guess I have been lucky up till now!!!!

 

I know there is a main ground at the drivers side pillar and that the center gauge has a ground under the shifter plate. It should be between the heater controls and the ashtray, but it could have been moved. (Still in the same general area though.)

The only other thing I can suggest is getting a tester and checking to see if there is 12v at the lamp sockets that aren't working. If there is, you know for sure you're missing the grounds.

Good luck, I don't care much for car wiring!

 

Just track down one thing at a time....


Get an inexpensive meter ($20)

1) Disconnect the positive at the battery first-

Put the meter on ohms-Ω and touch the metal on back of the gauges w/ one lead and the other to the negative battery terminal. It should read close to zero. If not- there's your problem.
Your are making sure there is a path back to the battery. Trace the wires back- and test them the same way-like where they are bolted down- one lead on the bolt- one to the battery...keep going back till you find a ground.

Caveats-

Bulbs can act as a resister in the circuit- make things work in certain scenarios when there is no ground- in these cases the meter will read low -a couple of Ω's but not be a real ground...

AND the radio- can see a ground through the antenna coax- disconnect the antenna and see if it still works.

Fuses- just because they look good - doesn't mean they are, There's several ways to test -With no power- measure continuity across the fuse- Meter on Ω - one lead on each side of the fuse - or if its in the box-you can touch the terminals. Should see close to zero.


Then touch the steering column- same way.

Only after you have made sure you have a good grounds- then move to the next step.

2) Checking for power-Go ahead and hook the battery back up. Start at the end of the circuit and work your way back.

Example- Put meter on DC voltage- pull a dash light bulb out- put one lead on the wire the other lead on a confirmed ground- turn on the light switch- should see 12 volts or there abouts. If you see power -then it's a bad bulb... No power- then follow the wire back to the switch-when at the switch check for power-same way ...then to the fuse box...


Hope this helps-

Richard

 

Great Info Thanks very much. Over the years I've dealt with so many issues with C2's, other C3's, a ZR1, many different C5's but have stayed clear of the electrical. Will report back after I check out your tips Thanks Paul