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Here are the symptoms and I'm hoping to find a cure. Courtesy light fuse blow immediately - no instrument lights - running lights are always on when the car is turned on. All other lights function fine. Am I looking at more than one problem or are they related somehow? Needless to say I'm not an electrical engineer
The courtesy lights are on the same circuit as the clock and lighter. Unplug them both and see if the fuse still blows. Is the dimmer on the light switch turned all the way to the left (CCW) to the courtesy position? If you turn the **** back and forth does the instrument lights come on? Is the instrument light fuse blown? What are you calling running lights?
Spend a few minutes tracing that circuit on the wiring diagram. Note everything connected to that fuse. One of the things you will find is that there is a pigtail under the master cylinder that powers the optional under hood light. Every car came with this, and it often gets nicked or pinched when work is done in that area. This will immediately cause the fuse to blow.
I had a bad element in my lighter. if was pushed in it would immediately blow fuse. Then if replaced fuse would blow again. If lighter was pulled back out, ok until pushed in again, that was a easy fix that time.
Thanks for all the help - I may be getting closer. I disconnected the clock and the lighter but the fuse still blows immediately. I'm thinking Joe's idea of the pigtail serving the under hood light is a possibility - there appears to be some sort of junction box there and the wires look like they might have been fried - picture attached.
Although the fuse for the instrument lights checked ok on the meter it must have a very small short in the fuse for when I replaced it the instrument lights work fine.
What I meant by running light are all the lights that come on when you pull the light switch to the first stop - pretty much everything except the headlights and backup lights.
First, that "junction block" is a circuit breaker for power accessories. What options are on the car? In any case, it is unrelated to any light circuit.
Second, spend some time looking at the wiring diagram. The TAIL fuse feeds the running light circuit in the headlight switch. This includes the front parking lights, tail lights, side marker lights, and under hood light. This fuse ALSO feeds the rheostat for the instrument panel illumination lights, through an internal connection in the headlight switch. From the rheostat, the circuit leaves the headlight switch, feeds the small INST LPS fuse, and from there powers the instrument panel lights. Again, the instrument panel illumination lights are actually wired with TWO fuses in series, the INST LPS fuse and the TAIL fuse. The instrument panel lights cannot come on if there is a problem with the running light circuit, unless there is a major problem somewhere.
Thanks Joe - I sincerely appreciate your help. Both the tail fuse and the inst fuse are good. The instrument lights work fine as does the light switch rheostat. I will start trying to trace all the wiring to the interior courtesy lights for a bad connection.
Okay - I located the courtesy lamp connection behind the clock. When I disconnect it the fuse still blows - is it correct to assume the problem is between the fuse box and the harness before the connection?
No, all the items on that circuit are hooked in parallel. So the short can be anywhere in the circuit from the trunk light and/ or engine light (if installed), lighter, clock, glove box light, map light, console light, or any of the courtesy lamp feed wires, back to the fuse box
It's time I surrender - short of removing the dash I have traced and checked every light I can find associated with the courtesy lights but to no avail. I've gone this long without them and I guess I can get along without them in the future.
So now I'm ready to move on to why the running lights are always on while the car is running - any ideas out there?
I had the same issue after I had new floor panels installed; the insulation on the wire that went back to the trunk light was messed-up, and it was shorting out on the floor. The wire harness for trunk light goes under the driver side seat (other wires in the same harness, in my car, include rear courtesy lights, power bench seat & convertible top control)
July 2nd, 2018, 04:37 PM
