Okay, I am really irritated with this.

1. I cannot find a short in any wiring

2. The parking lights, which did blow a fuse no longer blow a fuse (more on this later)

3. Now the headlights do with the ignition on

4. The parking light, tail lights, and brake light on the LEFT SIDE ONLY do not work

5. Could the headlight switch be the problem?

6. I have a fuse at the battery. With electronic ignition and carb, how many amps is reasonable for that fuse?

Thanks.

I'll be of little use here, but here we go.

1. Good
2. Good
3. No shorts, check grounds, that power is being drawn for some reason.
4. Grounds, mine did the same thing until I cleaned them all.
5. Don't know
6. LESS

Smitty

Another general consideration is your license plate light wiring. Make sure there are no wires shorting to the frame or each other. Easy to overlook.

Lic plate lights, and rear trunk light can both cause issues if not plugged in correctly.

Rear LP light didn't work before, I haven't touched it. And there isn't a trunk light.

Prior to the fuse snapping (i've used several), and after. . I smell a bit of old hot wiring in the passenger compartment.

Right now, I'm only using a 20 Amp fuse for the WHOLE CAR fuse.

Thanks guys. . and ladies.

Tail lights wired correctly?

20 amps for the whole car is insufficient if the headlights, running lights, engine, and associated systems are in use.
These cars will use between 20-40+ amps depending on what all is on.
Engine on and running- fuel pump about 5-6 amps- more upon initial start up of the fuel pump, but goes down rather quickly, same for all motors, IE. heater blower, fresh air blower. Could be 8-10 amps upon start up, but rapidly decreases to 5-6 amps. About 100 mili seconds to steady state amperage.
coil about 3-4 amps depending on the coil you are using and it's duty cycle ( percent of on time versus off time) It is on when the points are closed, off when the points are open
ECU about 5 amps, mostly fuel injectors at about 12 volts/3-4 ohms (3-4 amps)but on a duty cycle of mili seconds per event versus miliseconds when off
AAR about 1.2 amps constantly
big ones are the headlights, 60 watters are 5 amps each continuously and the motor that operates the headlights about 5 amps each, more on initial start up
Side and running lights, maybe a amp or less each side
start adding these all up and your 20 amp fuse is too small.
Remember the alternator puts out 50 amps for a reason, all systems may add up to near that when all are in use.
In my fuse block thread there is a list of current values ( amps )that I researched, they may be a little off, but should be fairly close.
I run 20 amp fuses for the two 4.0 mm wires and 15 amp fuses for the smaller 2.5 mm wires with no problems.
hope this has helped,
Tom

I agree with checking the license plate lights. Why is that one not working? If it's because it's grounding out, you can pop fuses and/or cook wiring.

Please don't ask me how I know this

Did you change or move anything before this happened?

Which fuse is blowing with the headlights on?

I recently had a similiar problem. Then I remember I had repainted the inside of my front turn signal lights. I reversed the two wires (not ground) coming into the light, and that's all it took. I was blowing a fuse everytime I put the hazards on, high beams didn't work, it was a PITA.
THEN I thought I should double check the wires and there it was, I had the wires in on the wrong terminals-problem solved. That went on for a week!!!!

Any electrical changes you made recently that seem to simple to be the problem? Double check those connections!

I pulled the speedo to do a cable lube. Put it together and then the fuse popped. It is a fuse on the battery, it popped with JUST the parking lights.

However, NOW, the 20A (which may be too light) popped with the headlights and key on.

I removed all the instrument light wiring because I thought that was the problem . .it is not.

The weird thing was that no changes were made before this happened. . except the speedo lube. Everything worked. . then suddenly POP

Doesn't the speedo cable act as an alternate ground source when the actual grounds start to fail? Seems to me I read about a cable (maybe the accelerator cable)
Shit like this use to happen to me on my british cars. Always ended up being a ground. Major PITA

Do you have a pic of your fuse set up? What type of fuse? "All fuses are not created equal". The new ATC fuses are rated at 125% continiously and up to 300% for very short periods, ( 100miliseconds).
If you don't think 20 Amps is too low, just check the values of the fuses in the underdash fuse panel. They add up to over 100 Amps. Of course they are overrated, else they would blow! But they are rated to blow prior to circuit damage, IE: "the wiring" part of the circuit
Using only one fuse is asking for problems, IMHO. To get one large enough to provide the current needed, you will be taking a chance of having a single wire short and burning that wire.
Tom

I have all the old fuses in use under the dash, this is additional. It is the new plastic type fuse. Belt and suspenders both

Sounds like an ATC. Try a 30 Amp one, but give some thought to seperating the 4 red wires and fuse them individually. You should have two 4.0 mm ones and two 2.5 mm ones that connect to the + battery terminal, or maybe now, to your fuse.
Tom

Now that you mention it...I think that certain circuits connecting to the headlight switch do control left/right sides of the car for certain items like parking/hazard lights. Check the wiring diagram.

Allrightie: The silly little ceramic fuses were not in place. Fixed that. All lights worked!! Yay.

So, I started the car (elec fuel pump and elec igntion) and turned on the headlights. . the car ran about 30 seconds before the 30 amp fuse on the battery popped.

However, NONE Of the ceramic fuses have blown in all this. Wouldn't one of them blow if there was a short in the light wiring?

My thought is now (based on recommendations here) is to split that fuse at the battery into at least three (I have three holders. . bought out my local NAPA) and see if that cures it.

If there was a short, wouldn't one of the lesser ceramic fuses pop first?? Yes? No?

Thanks

The 4 red wires on the battery are" Constant power to the fuse panel and constant ignition switch power and alternator charge wire.

I would put 4 fuses, one on each wire. I would use 20 amp fuses on all 4. 15A would be fine for the smaller ones.

I thought all 914s had a trunk light? front left corner of rear trunk. Wires in engine bay. May be wrong.

All the wires are the same size. It may have had a trunk light, but it is gone. Two POs ago, a "refurbish" was happening. .some . . interesting things

Ill try to find another fuse thingie. . I guess I'll have to go to another town LOL. I live in an interesting area.

So, do you think it is just too much for one fuse since the ceramic fuses aren't blowing?

Those 4 red wires are un-fused from the factory. If one shorts out under the dash, your car will burn to the ground. Not a big deal when the car was new but 40 years later, most wiring systems have been hacked.

With 4 separate fuses, if one blows because of a short, it isolates part of the circuit. This makes it easier to find the shorted wire. Look only at the stuff that doesn't work.

Well, the wipers and horn don't work, but they didn't before this either.

Did your issue ever get resolved?