As I tell this, keep in mind that my brake lights and turn signals were working just fine at the beginning of the day when I went to work this morning.
This afternoon I decided to put new brake light fixtures on my YJ. It is a pretty routine job, and all that it really entails is unclipping the harness from the old one, and clipping the new harness on. After I put the new brake lights on, this is what happens. With no headlights on, just regular daytime driving, the brake lights and turn signal works perfectly fine. When i turn on my headlight switch, the break lights do not work, and the turn signals do not work. The turn signals do come on but they stay solid and are very very dim, like the fixture is not getting enough voltage or something. I'm wondering if it just needs a new switch somewhere. All the fuses are perfectly fine.
I haven't run into it before where everything works without the headlights on, but as soon as you turn the headlight switch on nothing works except the headlights. Any thoughts?
Also, is there more than one fuse panel in the 88 YJ? I know there is one under the dash, but for some reason I feel there should be another fuse panel somewhere, and it is not under the hood.
They are just the standard light fixtures. I was looking into the LED's, but for now I just stuck to the regular ones. I have the Haynes repair manual, but it doesn't really seem to be helping me very much. Thank you in advance for any help. The new fixtures are just like the old ones, it was just weird that they worked fine this morning, and then after i put the new fixtures on the problem started, and i put the old fixtures back on to see if it was just the new fixtures, but then the old fixtures didn't work.
After looking in my Chilton YJ manual, which I forgot I had...the wiring diagram shows that the operation for the turn signal and brake lights with the headlight switch off is a totally separate circuit from when you turn the headlight switch on.
There are two sides the the headlight switch. One goes to operation of the headlights, and the other goes to the brake and turn signals. The headlight switch is good because the other side has one leg that goes to the gauge lights, and then the other leg goes to the front and rear turn signals/brake lights. I wonder if the turn signal switch in the steering wheel needs to be replaced.
Figured it out! The new fixtures have this crazy grounding system that jumps all over the place, whereas the old one has only one ground wire in it...the ground wire in the new one is hooked up to some weird things...now that I know what is going on I'll be able to just mess with the new fixture now to see if I can get it to work.
It sounds to me like Somewhere, there is what would normally be a ground hooked to Positive wire and a positive hooked to the ground. in a normal situation this would still work fine, unless there is another positive line that shares the ground as a common wire.
At least one of your situations would point to this, but I am still trying to figure out exactly which combination would cause your symptoms.
The only place the Headlights and other lights share a common system is at the bulb itself where the outer socket sheath should be the same as chassis ground. If you had a multimeter I would tell you to check to see if you get a short from the body to the bulb socket.(which is what you should see)
If you have one of those 12 volt testers you can turn on the lights individually and see if any on them cause the 12 tester to light up. it should not light up in any situation when clipped to the body and touching the outer socket. the only time it should light up is if you are touching the center conductors in the socket.
All of this effort for some stupid rubber washers that were on the bolts that fastened the brake lights to the frame. They were preventing the bolts from making good contact with the ground plate in the fixture, to the frame. Thanks for all the effort and help! Sorry for being dumb! haha
I wouldn't call it dumb. I always look at this stuff as a learning experience and makes you more capable to help others when they run into problems. Plus it helped me out, I finally have a working schematic for the entire turn/Hazard/brake system, which I had been trying to figure out for awhile.