I just got my 1978 C3 back from my Mechanic; who (among other things) replaced my old cracked Dashboard with a new one. I now have several Electronics problems:

1. My Head Lamps don't flip up (They still come on, but not flip up)
2. My Instrument Panel lights don't come on
3. My Turn Signals don't work anymore. (Neither the external lights blinking nor the instrument panel blinker arrows)
4. My Windshield Wipers don't work anymore
5. My Car Stereo doesn't come On anymore.
6. My Car Antenna doesn't come Up anymore

I will (of course) return my car to my mechanic to have these problems fixed if necessary; but will attempt to fix them myself if anybody knows of some (relatively speaking)
simple fix I can do myself. i.e. Is the Light Switch not re-connected properly?, Is something not grounded properly? (I see a Red wire [among a hundred other wires]
that is just hanging down under the steering wheel {which appears to belong to my Car Stereo} with a 'connector end' to it; but have no idea where to connect it to.
I've tried connecting it to the IGN plug and then to the ACC plug on the Fuse Box - but nothing happened once I started up the engine. ) I can't find any other logical connection site to plug it into under the dash.
I don't see any blown fuses on the Fuse Box panel. ??? Anybody have any ideas?

Chaz

 

For the headlights not coming up I would guess he didn't hood up the vacuum lines to headlight switch or the manual over ride switch correctly and for your various electrical issues I would definitely be able to explain to you how to test those, but it would be very confusing unless you have a wiring diagram. I could send you a pic of mine if you don't. It kinda sounds like your wiring has been messed with if you could send a pic of the underside of your dash with the AC ducked removed that would be very helpful.

 

Also for the blinkers you could check to see if he didn't hook the flasher relay back up it's behind the glove box you just remove the inside of it and it should be a light blue or silver cylinder.

 

Do the gauges and tach work? There are wire harness plugs behind the gauge panel and between the Speedo and tach.

to get at the back of the gauge panel to reach the plug you need to loosen the console panel but not need to remove it. You then need to remove the trans tunnel panels. The remove the screws holding the gauge panel. You can the get some room to reach behind the gauges and plug in the plug.

as I remember the easiest way to reach behind the tach cluster is to lay on your back with your feet over the back of the seat. Removing the seat - four bolts- will make it easier. You will also have to remove some HVAC vent tubes. Then reach up there find the lug and plug it in.

the Speedo has its own cable that slips into a fitting on the back of the Speedo.

I don't think I have any pictures of these plugs. You are working blind.

I the radio has its own plug. Or maybe just wires if it a replacement after market.

this is a time consuming job but not necessarily a require any real special skills.

 

You're in a tough situation without the schematical tools to take on these projects, as one of the forum members mentions above. At the same time, I doubt I would return the car to your mechanic to fix...if he didn't get it even close the first time around. It is more than mechanical aptitude with this stuff, its both electrical and vacuum-related knowledge. I would suggest that you get ahold of the tools (schematics), work through each problem by trouble-shooting and learn how to maintain these systems. And as mentioned, it is really not insurmountable or difficult, probably requires more patience than anything else and its fun to conquer these beasts.

Here for example is one source who really does a nice job to post trouble-shooting tips and is a forum supporter..Wilcox Corvette. Here is a link to his hose schematic...one of the first areas to troubleshoot and figure out your headlamp vacuum operation.

http://repairs.willcoxcorvette.com/1...ission-vacuum/

You are also in luck because there was published a 1978 Electrical Troubleshooting schematic that is the best I've seen and used. Includes schematics of the component, where its located as well as the wire runs and colors.
Here, for example is a page from the 1978 troubleshooting guide. Its for the anti-theft alarm circuit along with power door locks

 

FWIW: Why did your mechanic not check any of this?

 

If all of those things worked before the work then it sure seems that your mechanic had no business working on your car

Presuming they worked before, the headlamps not rising is almost certainly due to the vacuum hoses that operate them being connected improperly.

Assuming that you have intermittent (delay) windshield wipers the electrical problems you mention are likely the result of a disconnected or broken ground connection for the cabin wiring harness.

 

Except for the headlights, I would look for the ground wires for these systems as mentioned above. There is one main ground connection that goes behind the dashboard on the driver side I believe. If he didn't hook that up it might explain some of the problems. That would be where I would start since it is the simplest to look for.