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Unread 02-20-2012, 02:24 PM   #1
oskar
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1988 YJ Wrangler 
 
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No brake lights - I'm stumped

I've had trouble with my brake lights since I bought my YJ. I don't think they ever worked until I replaced the brakelight switch. Recently, they went out again, but I also had other electrical issues.

First, when the key was in the "ON" position, the gauge lights would flicker with the taillights, even though I had the headlight switch off. I replaced the headlight switch and cleaned the rheostat (interior dimmer switch) and I think that solved that issue.

I don't have brake lights now, and this could be a completely coincidental issue. The tail lights turn on when I turn on the head lights, and the turn signals work correctly, so the bulbs appear to be fine, as well as the wiring for that circuit. I have continuity between the two terminals on the brake light switch connector as well, but when I try to jump the connector, I still don't have brake lights.

I tried replacing the brake light switch as well (before I did deeper digging) but it still didn't help. Fuse looks good too.

Any suggestions?

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Unread 02-20-2012, 02:33 PM   #2
scubamc
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Have you checked your grounds?
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Unread 02-20-2012, 04:35 PM   #3
oskar
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Quote:
Originally Posted by scubamc View Post
Have you checked your grounds?
which ones should I check? The one from the battery looked fine, under the dash is a rat's next due to PO putting in who knows what previously..

I have an update on the symptoms. I'm thinking there has to be a short somewhere.

When the key is off, nothing is on (good)

When the key is in the ON position, the gauges light up when the headlight switch is off, and sometimes flicker. As I move the rheostat (interior dimmer switch) around, the gauge lights sometimes turn off and turn back on.

If I turn the headlights on while the key is out of the ignition, the blower motor turns on and seems that the rheostat sometimes controls the resistance to it on lower speeds (it goes slower and faster).

I unplugged the rheostat and the headlights and taillights still worked. Blinkers also work while the key is in the "ON" position.

Could a bad rheostat cause all of these issues? I put the multimeter on the two end terminals and got ohmage on all settings except all the way low, but it didn't seem to change much as I turned it up.

I also still don't have brake lights under any of these conditions, even if I jump the connector to keep it always hot.

Help would be extremely appreciated
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Unread 02-21-2012, 06:14 AM   #4
oskar
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quick update, I ordered a secondhand rheostat off a local forum, it should help aid my diagnosis a bit. If that doesn't work, looks like I'll have to start tracing wires.
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Unread 02-21-2012, 12:08 PM   #5
Cooter92YJ
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If you've already changed the brake light switch, and your fuse is good, fits tight, and is shiny clean, it's likely going to be in either the hazzard or turn signal switch. Not sure how your year is wired. Some on here say to cycle your hazzards on and off several times and then try it. These switches are prone to get dirty and gunked up, so you might get lucky and it just needs cleaning. You said your turn signals work, so it's probably not the grounds, though I would also check and thoroughly clean them as well. The ground for the stock tail/stop/ turn is the screws that hold the lights to the jeep. As for your other electrical problems sounds like you will need to do some serious looking/tracing to figure them out. The light rheostat shouldn't adjust the heater!!
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Unread 02-21-2012, 04:15 PM   #6
JWELK
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Grounds are OK as the turn signals work.
From the Brake Switch the current flows to the Hazard/Turn signal switch. Try operating the Hazard 4 way switch a few times. It is also possible the plug fell off the brake switch, but I think you would have checked that.
Can't tell you the wire colors, but look at the brake switch. One wire will be hot all the time, the other goes to the hazard/turn signal. It won't be the turn signal part as it get its voltage from the ignition key. It will be on the hazard side.

Regards,

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Unread 02-21-2012, 05:04 PM   #7
TheRobster
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My thought is still grounds. Whenever you have strange electrical issues start with grounds.
Luckily testing grounds is simple.
1. Grab your jumper cables.
2. Connect one end of the black cable to the - on the battery.
3. Connect the other black to the motor.
4. Connect the first Red to the black connect made in step 3.
5. Connect the last Red jumper clamp to a good chassis ground.

See what happens now.

Something changes. You have a ground issue.
Nothing changes. One more thing to check.

Use your jumper cables again, and connect from the battery negative to a ground near the back. (Maybe the fuel tank skid plate.

Test again.

Nothing changes. I am wrong. (Of course this never happens.)
Things work. You have a ground issue.
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Unread 02-21-2012, 06:42 PM   #8
oskar
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Quote:
Originally Posted by Cooter92YJ View Post
If you've already changed the brake light switch, and your fuse is good, fits tight, and is shiny clean, it's likely going to be in either the hazzard or turn signal switch. Not sure how your year is wired. Some on here say to cycle your hazzards on and off several times and then try it. These switches are prone to get dirty and gunked up, so you might get lucky and it just needs cleaning. You said your turn signals work, so it's probably not the grounds, though I would also check and thoroughly clean them as well. The ground for the stock tail/stop/ turn is the screws that hold the lights to the jeep. As for your other electrical problems sounds like you will need to do some serious looking/tracing to figure them out. The light rheostat shouldn't adjust the heater!!
It's funny you mention that, my turn signals weren't blinking until I turned the hazard off and on and they worked again. I also swapped with a flasher that I knew was good, but it was probably just coincidence and needed to be cycled. I'll pull apart and clean the hazard and turn signal switches tomorrow, and hopefully find some more information out.

I still have yet to be able to have any brake lights whatsoever with the brake light switch connector jumped with a spare bit of wire, and I do have continuity between the two terminals of the brakelight switch connector, so maybe the connection is stopping at the hazard/turn switch?

I've also noticed the radio is powered when the headlights are on, so who knows what the last owners did :/

I will try the ground trick to make sure it isn't a ground; thanks robster

Last edited by oskar; 02-22-2012 at 11:43 AM..
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Unread 02-22-2012, 11:37 AM   #9
oskar
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I took a video of my turn signals while on, and it seems they stay on and blink off instead of blinking on, but this could be normal and I could have never noticed it before. The hazards flash more quickly than the blinkers, but this could also be normal. Could anyone confirm for me?

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Unread 02-22-2012, 02:29 PM   #10
oskar
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New rheostat came in today, but I still have the same problems. Even if the rheostat isn't plugged in, I'm getting tail lights, head lights, turn signals, and flashers. the brakelight switch wires get 12V on the mulimeter when the key is on or off. If I unplug the fuse for the brake lights, the brakelight switch no longer gets 12 V. I even tried cutting the connector out and twisting the wires for the brakelight switch, still no brake lights.

What gives?
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Unread 02-22-2012, 03:40 PM   #11
oskar
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I found a diagram for a 90 YJ (should be similar enough), and it looks like the brake switch goes through the turn signal switch. I noticed my yellow wire coming from the turn signal switch looked like the insulation was gone in a few spots from rubbing etc, so looks like I'll try replacing that next.


Last edited by oskar; 02-22-2012 at 04:41 PM..
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Unread 02-22-2012, 04:43 PM   #12
oskar
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It just got dark out, and I noticed when the key is in the ON position, the gauge lights are still turning on and flickering when the headlight switch is off, and also the running lights are turning on dim. The new rheostat actually controls the dimness of the running lights. Lights are fine when I turn on the parking/headlights.

Looks like I have a short somewhere, guess I'll pull the steering column and trace some wires next..


I did try adding a ground between the dash metal and the negative terminal, nothing changed.

And my turn signals worked fine when I jumped and started her back up again, I must have just killed the battery to make them slowly blink.


Update: I played with some fuses, and when I removed the ACC fuse, the dash lights no longer flicker, so I probably have a short in that circuit. I still don't have brake lights, but maybe the turn signal switch will fix that. I have to replace the ignition lock anyways (ignition turns without key in it). Other than that I'm stumped.

Last edited by oskar; 02-22-2012 at 05:30 PM..
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Unread 12-27-2012, 04:10 PM   #13
slowdown675
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i know im super late on this but i had this happen on my 95 yj. i did everything i could think of like you and still nothing it was making me crazy. the fix was so simple for mine. i opened the tailgate and on the hinge side of the door there are two connectors and on the door jam there are two connectors (they look like bolt heads) so when the door is closed they touch and continue the circut. well they had gotten dirty and whir not letting the electricity continue. side note the brake lights and turn signals are the same light on the yj so that threw me off because the brake lights wouldnt work but the signals and running lights worked fine. i just cleaned the connectors and they work fine i will be wiring them together some how because it seems like a crappy failing set up. hope i could help somebody
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Unread 12-27-2012, 09:51 PM   #14
Grape Ape
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It sounds like you have a short in the wiring under the dash somewhere. If you have found some bare spots on one wire then you are almost guaranteed it is a short somewhere in some scraped up wires.

One quick bit of advice. If you are taking your column apart to work on the steering parts disconnect the battery. You ay not mess it up but in the process of removing the plastic around the column you might knock the parts loose on the high beam rod that goes down the column. If so it can short out on the back of your turn signal/wiper switch. They are hard to find and expensive. much easier if you just disconnect the battery.
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