my fuse for the lights in the gauges keeps breaking everytime I turn on the headlight. Where is the ground wire for the lights? Any help would be greatly appreciated.
thanks,
will

you have a short in that circut. start by isolating the different branches of the circut. do you have a haynes manual? get one if ou don't then learn how to read the wiring diagram. then you'll be able to isolate the section that is giving you the trouble.

Will - just lived through a fuse that kept blowing for my fog lamps. I'll bet it's a dash bulb that fell out of it's holder and is touching something it should not. In my early 911, my fuse did not blow and I melted a bunch of wires. I bet if you pull the gauges it will be obvious?

In my case, it was one of the license plate lights being hooked up backwards. (Stupid body shop...) A whole bunch of stuff gets powered by the gauge lights circuit; chase through the wiring diagrams to see what.

--DD

reading the haynes manual for the electrical wiring is like reading chinese for me. It is impossible.

Think of a waterfall of electricity falling to the ground.

The switches and such are like locks, and the electrons are like insanely fast boats.

b

Have you tried looking at the current flow diagrams for the 74's? For some things they are a little easier to understand. At least I find that way - not nearly as jammed together. Without being able to trace from the diagram it is going to be a long slow process.

I like Vance's suggestion of just having a poke around first.

Did this just start happening out of the blue or is associated with other work that you have done?

Mine did this. Turned out it WAS the gauge lights. I took ALL the light sockets out and inspected them. There's a contact in the bottom of the socket that is on a spring, and it pushes against the nub on the bottom of the bulb. Well, one of them was a bit off-center, and it was pushing against a bulb "nub" that was also off-center, which guided it over to where it shorted against the shell of the socket, which was ground. At least that's my theory.

Not sure if replacing the socket fixed it, or replacing the bulb with one that has a concentric "nub", but I did both. I also think that if the bulb is a bit crooked after installing it into the socket, that bottom contact may be pressing sideways on the bulb and may then be in danger of touching the grounded shell.... Be sure all of your bulbs seat squarely into their sockets.

Sorry no pictures....

Good luck!

Jim

Oh thats going to help him, damn now I am confused.

I bought my car with the gauges not working. I replaced the light bulbs in the gauges thinking it was just bad bulbs. Even with new bulbs the gauge light wouldn't turn on due to the fuse breaking. I will try tracing the wires for that particular fuse and see where it leads.
Once this is solved, the gauges are going to northhollywood speedometer for coloring and recalibration.

Was the fuse popping before you replaced the bulbs? If not then Jims story seems to fit you. Try removing them.

I guess it helps only if you liev by a river, or if you were a "wierd" kid.

I am both.

b

I see the analogy britt. So a short is like a little submarine hiding in the lock that blows the crap out of the lock doors and sends the little boats crashing to the ground right?

Reading the diagrams isn't all that hard. Which fuse is blowing? #7, perhaps? (Just guessing by a look at the 73 wiring diagram--what year is your car?) If that is the case, something "downstream" of the fuse is shorting to ground.

Locate fuse #7 on the wiring diagram. The 70-73 diagrams have a big box that represents the fuse panel, and little numbered things that represent the fuses. Look for #7--it's in the first page of this particular diagram. Trace the wires that come from it on the right side. One of them, a black/blue wire (black with a blue stripe) goes to component #28, which is the headlight switch. The other one, a grey wire, goes to component 18 (the rear trunk light) and two component 15s (the rear license plate lights).

You can unplug those to see if they have any effect on the fuse popping or not.

Inside the headlight switch, you can see the path runs from pin 56b up to 56a. From there we have two black/blue wires; one that goes to a big multiple-way connection and the other of which continues on the other diagram (look for a little #62). That 62 is in the upper-right of the 2nd page of the diagram, and it hooks into the center console instrument lights.

So, tracing out the lines on the wiring diagram should tell you what parts the wires in this circuit are hooked up to. Try unplugging them and keeping them from touching any kind of ground (e.g., any metal) and see if you get resistance from the "downstream" end of the fuse to ground, like the chassis. If there is close to 0 resistance, something is shorting to ground. You might have to cut off some connectors to isolate parts of the wiring (make sure you have decent crimp-on connectors if you try this!) or you may be able to work it out other ways.

One thing to remember when reading the diagrams--you have to assume that all wires connected together (without any "components", light bulbs, motors, switches, etc. in the way) are electrically identical to each other. So when you have a wire that goes to a connector, and a second wire is crimped into the connector and goes elsewhere (like the two grey wires on that component #18), that's the same effect as having a wire go directly to the first component, and a separate wire going directly to the second component. Does that make sense?

Anyway, I hope this helps you to read the wiring diagrams and start troubleshooting.

--DD

thank you all. I located the bad wire and it was my license plate lights. I took out both lights and located the wires. I then proceeded to wrap the wires with waterproof tape and wrapped them again with electrical tape. No more blown fuses. hurrah!!!!!.
once again, thank you.
will