DS Brake Light Problem (1 Viewer)

[HomersCanyonero]

I did a search, but still don't know what the problem might be.

If I turn on the headlights and press the brake pedal, my DS brake/tail light turns OFF and the PS brake light turns ON.

If I turn off the headlights and press the brake pedal, then both rear brake lights go on. However, the DS brake light is half as bright as the PS brake light.

The center bar brake light works fine. So, the problem is entirely on the DS brake light.

I replaced both bulbs (DS and PS) with new 1157 bulbs from Napa, but that didn't fix the problem. I do have a Hopy trailer light converter that I installed about two years ago, but I haven't pulled a trailer in a year.

I changed the fuses around and it didn't help either. The fuses look fine.

I might disconnect the Hopy trailer light converter to see if that helps, but should I replace the 1156 light bulbs as well?

Any other ideas on what to try?

Thanks

 

[80t0ylc]

Good idea to eliminate the trailer converter. The other thing could be a corroded or faulty DS light socket for the 1157 bulb. It appears that your tail light circuit is somehow shorting out both circuits on the DS. The light socket and 1157 bulb are the shared points for both these circuits and you've already replaced the bulb. Inspect that light socket with the bulb removed and be sure you don't have something in there causing the problem. There's 2 contacts about 1/8th of an inch apart down in the bottom - not too difficult for a sliver of metal to short out. Also be sure that bulb is screwed in completely. You'll notice that th 1157 bulbs are keyed so as to not get them in backwards. But if the bulbs contacts do not line up with the socket contacts, when installed you can have all kinds of problems.

 

[Clutchee]

Funny we are having similar issues

My thread:https://forum.ih8mud.com/80-series-tech/292100-brake-light-help-needed.html#post4572513

Good luck & let me know what you find.

 

[slopppy75]

Typical symptom with loose Ground!!
it sounds like you are missing ground at one point..
Take the lens out and trace the ground wire.
I cannot give you color or location because i don't have EWD right now, but you will find either loose ground bolt or broken wire.
make sure any screws that make electrical connection is very tight. They like to get loose over time creating all sorts of problems
let us know how it turn out.

 

[TrickyT]

Typical symptom with loose Ground!!
it sounds like you are missing ground at one point..
Take the lens out and trace the ground wire.
I cannot give you color or location because i don't have EWD right now, but you will find either loose ground bolt or broken wire.
make sure any screws that make electrical connection is very tight. They like to get loose over time creating all sorts of problems
let us know how it turn out.

x2. According to the EWD left and right sides share a common ground point, so your problem is likely right at the DS bulb socket or where the ground wire connects to the socket.

 

[HomersCanyonero]

I disconnected the Hopy trailer converter by unplugging the connector to the converter, but this didn't help.

I've checked the DS 1157 bulb and socket 3 times. I can see the ground wire under the socket, but I cannot get to it. I've pulled on the wire, but it feels like it's attached.

I've pulled apart the other wires and I've made sure there's contact under the bulb's two contact points.

Anyone have a picture on how to pull the metal socket off the plastic case? I'm guessing this is how you get to the ground wire's solder point to the socket.

I'm editing my original post with regards to how the lights are working. It's a little different than I first reported, but I'm still having the issue.

 

[TrickyT]

Use an multimeter and measure resistance between the metal on the bulb socket and a good ground point on the vehicle chassis. It should be 0 ohms or close to it. If not, then there is a problem with the ground for that socket.

 

[HomersCanyonero]

I added pictures. The socket is clean -- no rust issues.

I'll see if I can get a multimeter to check the ground's ohms.

I'm in Mammoth Lakes, Ca on vacation with the family and someone swiped my rear PS center cap and my air cap.

I've been doing some off-roading over here, but it's too much of a coincidence that I lost my center cap and air cap on the trails...

 

[80t0ylc]

TrickyT's right - you're gonna need a meter to solve this one. While it's apart, plug the bulb in to the socket. While you're back by the socket and bulb, have a helper turn on the lights and then step on the brakes. While the socket is malfunctioning, see if you can hear or see arcing. Report back your findings. Do you know how to use a multimeter?

 

[HomersCanyonero]

I checked for arcing (i had to look it up in wikipedia), but there's none. No noise, no heat, no nothing.

I checked with the headlights on and the brake pedal pressed (bulb is off with no heat and no noise and no light).

I checked with the headlights off and the brake pedal pressed (only one wire in bulb is on when both wires inside bulb should be on, but no noise and normal heat).

The hardest part of using the multimeter is to set it up correctly to measure the desired current or voltage.

 

[80t0ylc]

I checked for arcing (i had to look it up in wikipedia), but there's none. No noise, no heat, no nothing.

I checked with the headlights on and the brake pedal pressed (bulb is off with no heat and no noise and no light).

I checked with the headlights off and the brake pedal pressed (only one wire in bulb is on when both wires inside bulb should be on, but no noise and normal heat).

You should see one filament lit for brakes (bigger and brighter) and the other (smaller and dimmer) filament lit for tail lights. The only time both are lit is when you have lights on and step on brakes. So if you can see this correct function, one at a time, tells me the bulb and socket are fine. Prolly lose or bad ground connection, as others have said. If you can't get the one at a time right, you prolly have socket or wiring to socket problem.

The hardest part of using the multimeter is to set it up correctly to measure the desired current or voltage.

When you get multimeter, take a close up picture of the front and post it so we can help you set it up. There's so many out there it would be better and quicker to give you specific instructions. Once you get the hang of it you'll be able to transfer to other meters easier.

 

[NKP Garage]

Were you ever able to figure out the problem on this one?

 

[HomersCanyonero]

I've been driving with a bad DS rear brake light al this time. I got a multimeter, but I haven't had a chance to test it.

 

[HomersCanyonero]

Finally, problem solved. The ground wire was not making good contact with the socket. However, I had to take it to an auto electric shop and the guy fixed it in 5 minutes. Charged me $15.

He basically pulled the ground wire completely out from under the socket. He re-attached it directly over the socket to the metal casing inside the socket.

I had previously changed the light bulb, pulled the socket out and wiggled the wires, checked the volts and amps using a multimeter. The multimeter showed that there was something wrong with the amps. I didn't know how to fix, but I could tell something was wrong with the wires.

I'm happy it was fixed for $15 and it only took him 5 minutes to fix. I'll eventually have to fix it right by inserting the wire back into the back of the socket through it's original hole and solder it back to the metal case. For now, I'm just happy it's working.

 

[ETXLX450F]

Do you have any pictures of the repair you are talking about?

 

[AndrewInf]

Had the same type of problem. Two weeks ago I was out driving and when I pulled over to park a cyclist flew by at 20mph yelling "YOUR TAIL LIGHT IS OUT!" I checked when I got home and it all looked fine. Last night I parked at a restaurant and could see the reflection of my ass end in the dining room windows, both tail lights were out, and the upper brake light was on. Hitting the brakes made the upper brake light get a little brighter, but both the tail lights stayed dark. Turn signals and reverse lights worked as intended.

Limped home with the hazards on, got out the multimeter, did some testing and eventually figured out the grounds on both of the tail lights were bad where the white/black wire met the socket. From the outside they looked fine, I could see shiny clean copper down between the socket and the plug housing, but pushing the ground wire in and out of the plug made the light go on and off. This morning I found this thread and decided to go for it and attempt a similar repair to the one HomersCanyonero described.

I gently pulled the ground wire out -- didn't take that much force, it's not soldered in, it's just sandwiched between the plug body and socket when they assemble it. The last 1/8" or so of the copper wiring was a dirty gray, looked very dull, and had a few tiny specks of green copper corrosion. I snipped the bad ends off, stripped some more of the insulation off (so there was about 1/2" exposed), then I put it back through the little rubber grommet and slid everything back into the plug housing. I pushed the ground wire up so the end of the exposed copper was flush with the front edge of the socket, then I used some hemostats (any very tiny needle-nose type of pliers would work too) to bend the copper strands down so they were touching the socket.

Got out my soldering iron and tried soldering the wire to the socket housing - no go, it just beaded up on the wires and wouldn't flow onto the socket because of some surface treatment done to it, probably to inhibit rust. I pulled the ground wire back out of the plug a bit, sanded the socket down briefly where I wanted to solder, then put everything back. Solder stuck onto the socket beautifully and the lights seem to function as intended now. The upper brake light has gone back to only lighting up when I hit the brakes.

A few curiosities though; (a) that both of them went out simultaneously and in the same way, and (b) that the upper brake light was stuck on when both tail light and brake circuits were faulty.

I don't know what to say about (a), and I wonder if (b) is the result of some redundancy Mr. T designed into our cruisers so that two burned out tail lights will leave you with some rear markers.

Anyway, thanks for the info HomersCanyonero. I meant to take pictures but the repair was pretty straightforward once I was in there and forgot to document it.

 

[colt45]

Thank you for this post. My 1994 is doing the exact same thing. Gonna look at that this afternoon when I get home.