Wiring Diagrams

I started out simply adding driving lights on my '77 (mounts are on the car, but there were no lights) because I have a fondness for seeing where I'm going when I commute in the wee hours through deer country.
Anyway, I've got no power to the lights. More specifically, the fog light switch lights up on the dash when I pull it out, but I've got no juice to the relay coil. The Haynes manual has only the 73 diagram, showing the fogs wired directly though the switch (no relay), the '77 diagram doesn't show fogs, and the 81 shows fogs and a relay, but according to that I should be fine unless there's a break in the wires between the switch (it has power: it lights up) and the releay socket. I suppose it's also possible I've simply got a bad switch.
Anyone know where I can find model-specific wiring diagrams? Any experience with the fog light switch only partially working? Any hope of rebuilding it, or should I just plan on replacement? Am I missing something in the diagrams - like the engine needs to be running, or the fogs work only when the parking lights are on, not the headlamps?
Worse comes to worst, I can wire in around the whole system with a separate relay and switch, but that seems a bit much since all the parts are already in place.
TIA

I have the factory manual with the wiring diagrams that you need.
I can copy them and send them to you.
Chris

[Early_S_Man]

Dave,

The Haynes manual diagram on p. 224 shows the same diagram as the factory service manual, and it DOES, indeed, have a relay, device #5, as all of the factory option and retrofit-wiring-harness-equipped cars did have! The later '81-vintage circuit is similar, and has a more complex dashboard switch.

I guess the problem you have is determining whether you have the less complex switch or not! Hella makes an aftermarket illuminated fog/driving lamp switch, but it doesn't have the extra contacts for the rear fog lamp. It would bot be dificult to replace the factory switch with the similar-appearing aftermarket Hella switch.

Thanks, Warren,
I had missed that drawing.
I guess I have to trace back to find the source of the 12V that feeds the fog switch and make sure all the wires connect from the switch in the dash to the fuse/relay panel.
I've got a complete Hella system (had it on my Subaru wagon, but my wife's driving that now and couldn't care less about drinving lights). I'd prefer to use the factory switches and relays since they're already there, but will bypass them if I can't figure out why they don't work.
I'm waiting for my relays to come in so I can rewire the high beams. Planning to connect the two circuits so I can put the driving lights on anytime and also switch them on with the high beams.
I wish CIS were so simple .
It probably is, but I don't have the tools and experience.

Headlights on

So, check for power at pin "30" on the relay base (power all the time)

Check for switched power at pin "86" on the relay base (power from the fog light switch to turn on the relay)

Check for continuity to ground from pin "85" on the relay base (this is the ground circuit for the relay)

You can also jumper from pin "30" to pin "87" and your fog light should light up. That is if the fuse at location S-1 is ok.

Pin "87" is power to the fog lights once the relay has closed.

cwood,
I'm following the same path you outlined.
Power at pin 30 is OK.
GND at pin 85 is OK.
Continuity from pin 87 to fuse to foglights is OK.
I'm not getting switched power at pin 86, though the foglight switch lights up when pulled out.
Next step is pull out the radio (and maybe the switch?) to see if I've lost a wire at the switch.
Thanks for the help.

Bypassed a lot of troubleshooting and added a wire from left lowbeam fuse to the foglight fuse for the drive home.
SO why does one beam shake and vibrate when the other is steady and they're both using the same mounting arrangement?

Position 2 on the fog lamp switch should be the one that goes to the relay.
Position 3 on the switch is the one that goes to the switch light.
Position 1 on the switch is power to the fog light switch.

When you remove the switch if the wire on position 2 is connected. Remove the wire and check the switch at that terminal.
If you have power at the switch remove the wire at position 2 (blue/whit I believe) and check for continuity from the wire to the relay base pin 86.
If you have no continuity then go searching for a break in the wire.
Check the wire for butt splices (power in and out of the splice) also check the relay bas and make sure the wire has not pulled loose.
As far as the vibrating light it could be a loose mount, loose bulb, valance panel loose etc. Give it a light thump and see what moves.
Good luck

(sheepish grin here)
I had a ground on pin 86, but that was when I first looked at it, before I realized I was looking at relay #3 (horn?), not #2 (foglight) (because I was ignoring the frontmost, empty relay location. DOH!

That explains the wire with the big ring terminal hanging out of the front of the fuse block harness.

I did get to see a lot of stuff behind the dash that I hadn't looked at before. I may even tackle the wiper motor park switch.

So, lights now come on with the switch when the headlights are lit. Yesterday I got relays to mod the high-beam circuit. I'm planning to use two so I can force the driving lamps on when the high beams come on, regardless of switch position.

Still have to figure out the vibration. Will bump it and see.

Thanks for the words of encouragement

Well ya learned how to trouble shoot and your lights work. And you seem confident to tackle more areas so thats all that is important.
Have fun.