Electrical Right rear taillight issues

[_Fumbles]

Recently purchased this CJ7 , stripped it down to the chassis. New Painless wiring harness. Left rear tail light works correctly in all modes as do front lights/TS Right rear tail light not working correctly. I get the parking light when I turn on the headlights, however I do not ever get a brake light, hazard flashing or turn signal. I’ve traced back to the turn signal wire loom at the steering column and the connection/continuity is good to there but I’m not getting any electrical input coming from the fuse block to the turn signal harness connection. I took the fuse block off the firewall and looked for a loose wire connector or a pinched wire but did not see any indications. I’ve checked the fuses and all of my ground connections but to no avail. I’m hoping that someone might be able to help. Is there a hidden fuse somewhere that I’m not seeing?

 

[CJ]

Even with a new painless harness bad grounds kill you.

Check your grounds,,, Especially at the lights.

 

[_Fumbles]

Even with a new painless harness bad grounds kill you.

Check your grounds,,, Especially at the lights.

Does that explain how the parking lights work but nothing else? I checked that ground at the light yesterday. Pulled the screw out and made sure the metal was bare then re-connected the ground again at the right rear TS. Maybe it’s a ground up by the turn signal switch harness/steering column? Or maybe the ignition switch? IIRC - the right rear TS worked at first then it quit if that’s any help…
The previous owner had ridden this Jeep pretty hard so anything is a possibility. I’ve replaced so many things & welded up broken brackets it’s astounding that it still drove.

 

[j6824]

A lot of guys run dedicated grounds from all four corners to a bus bar on the interior firewall fed straight off the battery neg

Grind it shiny and slather with dielectric

Can't hardly overdo the grounds on these things

Worth consideration is battery cable grounds tub to frame, frame to block, starter to frame

 

[_Fumbles]

Yep - I picked up a bus bar thingy - I’ll hook it up next. I ran grounds frame to body & front grille, starter to frame, engine block to frame. I’ll check all of my grounds tomorrow

 

[TSB8C]

If the tail light is working when you turn on the headlights, your ground connection at the light (through the mounting screws) must be good. There is no separate ground for the taillight vs the brake/turn signal light. It's the same dual filament bulb (unless you have LED lights). Then the backup light is a separate bulb, but also shares the same ground connection to the mounting screws through the metal bulb socket parts inside the housing. If you have continuity from the brake light/turn signal wire at the rear all the way up to the turn signal harness at the base of the column (where the wires then go up to the turn signal switch itself) then most likely it's an issue in the turn signal switch. Your brake light switch has a single "in" (+12V) and then an "out" that goes to the turn signal switch. Inside that switch is where it is "teed off" or separated to the two sides via the switch itself. An easy test is to apply +12V to the right side turn signal wire at the base of the column and confirm whether the brake light/turn signal comes on or not. Use a small probe or sewing pin/needle to press into the connector along with a jumper to apply +12V to the probe. In other words, just jumper +12V to the correct pin in that connector and see if it turns on the light. Your right rear brake/turn light is the green wire in that connector. Here's a pic:



If you apply +12V to that green wire and your brake/turn signal light comes on, then the wiring, connectors, and ground at the taillight are all good and the issue is in the turn signal switch itself. If not, then you know where to troubleshoot. You can also use your volt meter to check for +12V on the white wire coming from the brake switch to confirm it is working when you press the brake pedal (must be though if your left side is coming on).

 

[_Fumbles]

If the tail light is working when you turn on the headlights, your ground connection at the light (through the mounting screws) must be good. There is no separate ground for the taillight vs the brake/turn signal light. It's the same dual filament bulb (unless you have LED lights). Then the backup light is a separate bulb, but also shares the same ground connection to the mounting screws through the metal bulb socket parts inside the housing. If you have continuity from the brake light/turn signal wire at the rear all the way up to the turn signal harness at the base of the column (where the wires then go up to the turn signal switch itself) then most likely it's an issue in the turn signal switch. Your brake light switch has a single "in" (+12V) and then an "out" that goes to the turn signal switch. Inside that switch is where it is "teed off" or separated to the two sides via the switch itself. An easy test is to apply +12V to the right side turn signal wire at the base of the column and confirm whether the brake light/turn signal comes on or not. Use a small probe or sewing pin/needle to press into the connector along with a jumper to apply +12V to the probe. In other words, just jumper +12V to the correct pin in that connector and see if it turns on the light. Your right rear brake/turn light is the green wire in that connector. Here's a pic:

View attachment 75379

If you apply +12V to that green wire and your brake/turn signal light comes on, then the wiring, connectors, and ground at the taillight are all good and the issue is in the turn signal switch itself. If not, then you know where to troubleshoot. You can also use your volt meter to check for +12V on the white wire coming from the brake switch to confirm it is working when you press the brake pedal (must be though if your left side is coming on).

Oh man… I forgot to say I went to LED’s on the headlights/taillights & front turn signals. I did use the proper electronic turn signal & hazard flashers from Painless & the Painless LED headlight wiring loom with relays.
I’ll introduce 12V into the turn signal circuit at the column and see if the lights come on. And yes the reverse lights on both sides work.
So what I am seeing in your picture is the power comes from the brake pedal switch in the white wire and gets transferred out to either turn signal via the turn signal switch correct?

 

[TSB8C]

That is correct on the brake switch power on the white wire. So if you hit the brake pedal and one side comes but not the other, you must be getting power from the brake switch to the white wire, then it goes to the turn signal switch, to then come back down both the yellow and green wires and out to the rear lights. So if it's coming down the yellow wire for the left light, but not the green wire for the right light, that indicates an issue in the turn signal switch. Inject +12V to that green wire in the connector and that should send power directly to the right rear light, bypassing the turn signal switch.

I also did the LED conversion of all my lights as well. Love 'em. Didn't bother with the relays in the harness, just two 100 ohm resistors at the front turn signals and the LED flasher units in the fuse box. Then some LED headlights, and no more bulbs. And since I have the Dakota Digital gauges, those are all LED too. My last bulbs are the six heater control and headlight and wiper indicators.

 

[_Fumbles]

I’ve pretty much done the same thing with my dash the only incandescent bulbs are the ones in the indicators and the tachometer.
OK so I introduced 12V to the second and third terminal wires (left and right brake lights) and both of them illuminate at the taillights. So the issue must be with the turn signal switch which doesn’t make any sense to me because I replaced it with a new one and then I ordered a second one from a different maker and have plugged this one in as well and it still doesn’t work correctly.
I also just tested the ‘white’ brake wire and it’s got 12V going to the turn signal harness.
Sent you a PM request…