Nacho-RT74
Well-Known Member
Damm! Allways forgett if is 18 or 16 LOL
72 Charger Tail Lamps not Lighting
- Thread starter JR_Charger
- Start date
JR_Charger
Well-Known Member
Anything wrong with O'Reilly's Dorman 16 guage wire?
Nacho-RT74
Well-Known Member
Nothing wrong with it. Althought for correctness and if you care, should be gray
JR_Charger
Well-Known Member
Little on my car will be "correct," but five years from now someone who needs to know may find your comment.
JR_Charger
Well-Known Member
I pulled the bolts out of the bottom of the tailight housing -
The metal on the bumper and the wire loom has a couple coats of Rust-Oleum rust reformer on it. I sanded the area under the bolt down to bare metal (or chrome in the case of the bumper), and replaced the bolts with new stainless steel bolts, because the originals look like this now -
I've been refinishing the old rusty hardware via a medieval-era technique that involves heating the bolt with a propane torch and dipping it in oil. The oil burns off and the smoke and soot fill the pores of the metal and coat the bolt. I'm guessing the finished bolt does not conduct electricity well.
Unfortunately this was not enough to establish a ground.
My bumper bolts have also been treated this way, and possibly the bolts that hold the bumper bracket to the rear trunk panel of the car. The bumper brackets and the rear panel of the car have been coated with rust reformer and painted. It's not surprising that there is no ground path through the bumper/bumper brackets/rear trunk panel.
I'm trying to learn how to test for ground at the sockets. I've got a digital multimeter, and set it to continuity to test the sockets. It buzzes with the red probe in the socket and the black probe on the ground in the trunk (the ground for the driver's side marker lamp). It buzzes with the red probe in the socket and the black probe on one of the new bolts I put in the tail light housing. I take that to mean there's no ground, but the multimeter didn't buzz when the red probe was in the socket and the black was on a license plate screw. I don't understand that.
The metal on the bumper and the wire loom has a couple coats of Rust-Oleum rust reformer on it. I sanded the area under the bolt down to bare metal (or chrome in the case of the bumper), and replaced the bolts with new stainless steel bolts, because the originals look like this now -
I've been refinishing the old rusty hardware via a medieval-era technique that involves heating the bolt with a propane torch and dipping it in oil. The oil burns off and the smoke and soot fill the pores of the metal and coat the bolt. I'm guessing the finished bolt does not conduct electricity well.
Unfortunately this was not enough to establish a ground.
My bumper bolts have also been treated this way, and possibly the bolts that hold the bumper bracket to the rear trunk panel of the car. The bumper brackets and the rear panel of the car have been coated with rust reformer and painted. It's not surprising that there is no ground path through the bumper/bumper brackets/rear trunk panel.
I'm trying to learn how to test for ground at the sockets. I've got a digital multimeter, and set it to continuity to test the sockets. It buzzes with the red probe in the socket and the black probe on the ground in the trunk (the ground for the driver's side marker lamp). It buzzes with the red probe in the socket and the black probe on one of the new bolts I put in the tail light housing. I take that to mean there's no ground, but the multimeter didn't buzz when the red probe was in the socket and the black was on a license plate screw. I don't understand that.
64fury74charger
Well-Known Member
If you have already done this then disregard my suggestion. I haven’t read the entire thread. Carefully check the ground wire in the harness from the sockets to the first connection and wiggle the wires to check for broken wires inside the harness.
Find a clean ground inside the trunk near the side marker light and run a fresh ground wire to the sockets and see if your lights work. It’s either ground or power and start at the light sockets and work back bypassing the harness until you find the problem area. Then you will see what you need to fix.
Fresh wire from a spool is a great testing tool. Lots of problems with wires broken inside the insulation and you can’t obviously see the problem and things will work intermittently until they don’t.
Find a clean ground inside the trunk near the side marker light and run a fresh ground wire to the sockets and see if your lights work. It’s either ground or power and start at the light sockets and work back bypassing the harness until you find the problem area. Then you will see what you need to fix.
Fresh wire from a spool is a great testing tool. Lots of problems with wires broken inside the insulation and you can’t obviously see the problem and things will work intermittently until they don’t.
JR_Charger
Well-Known Member
The only ground in the 72 tail light wiring harness is the one for the driver's side marker lamp.
I attached a wire to the side marker lamp ground and touched it to the driver's side tail light sockets. I only had to touch one to get both to light up. So that's progress.
I touched the wire to the passenger's side tail light sockets, and all I got was sparks. The bulbs didn't light. Why would that happen?
I think I'll have to replace one of the passenger side sockets. I can't get the bulb to seat right, it keeps popping out on one side.
My turn signals are acting like emergency flashers now - they both turn on either way I signal. The HVAC control lights flash as well, and my aftermarket tach flashes, and the instrument cluster lights flash. The IC lights that illuminate the cluster - the turn signal lights in the cluster aren't doing anything. I hope I haven't short-circuited something in the new turn signal switch.
I attached a wire to the side marker lamp ground and touched it to the driver's side tail light sockets. I only had to touch one to get both to light up. So that's progress.
I touched the wire to the passenger's side tail light sockets, and all I got was sparks. The bulbs didn't light. Why would that happen?
I think I'll have to replace one of the passenger side sockets. I can't get the bulb to seat right, it keeps popping out on one side.
My turn signals are acting like emergency flashers now - they both turn on either way I signal. The HVAC control lights flash as well, and my aftermarket tach flashes, and the instrument cluster lights flash. The IC lights that illuminate the cluster - the turn signal lights in the cluster aren't doing anything. I hope I haven't short-circuited something in the new turn signal switch.
64fury74charger
Well-Known Member
This sounds like there’s something wrong in the right side harness. Check the tail light harness and see if there’s a split in the middle that connects both sides. If so separate them and see if the problem is just the right side of the harness. You may have damaged sockets causing grief.
The light sockets can sometimes be reconditioned or you may able to separate and repair the posts that power the bulbs. There is a small spring under each post and you can cut the wires one at a time and remove the posts.
Straighten the sockets carefully so the bulbs will seat properly. Be aware the the dual filament bulbs have offset grooves in the sockets to line up the posts so it only goes in one way to lock. I hope this helps you work through this problem. Electrical is not
fun, but it’s good to learn as you go.
JR_Charger
Well-Known Member
I looked and couldn't find any problems with the passenger side wiring, other than the one socket where the bulb doesn't seat right.
JR_Charger
Well-Known Member
Is there such a thing as a tail light socket with a ground wire? I'd replace all of these sockets before I'd try to reach up behind the bumper with a soldering iron to stick a ground wire on them.
JR_Charger
Well-Known Member
Making progress! I grounded the tail light bezels and now the lights turn on. However, the reverse lights don't turn on and the turn signals and hazards don't flash. The license plate light doesn't turn on, but I haven't checked the condition of the bulb. I don't know if the brake light function works.
Here's my ground set up -
One ground wire with a ring terminal jammed between each light bezel and the bumper -
The ground wires run to a distribution block underneath the trunk latch catch. The bolts for the trunk latch catch just happened to be the same width apart as the holes in the distribution block, so that worked out well.
I've currently got the main ground wire run to a bolt for the EGR line -
Is this a big no-no? There are no gas fumes in there at the moment. Logically, the whole chassis of the car should be a little electrified as the return back to the battery negative post, so I'm not sure this would make a difference.
Here's my ground set up -
One ground wire with a ring terminal jammed between each light bezel and the bumper -
The ground wires run to a distribution block underneath the trunk latch catch. The bolts for the trunk latch catch just happened to be the same width apart as the holes in the distribution block, so that worked out well.
I've currently got the main ground wire run to a bolt for the EGR line -
Is this a big no-no? There are no gas fumes in there at the moment. Logically, the whole chassis of the car should be a little electrified as the return back to the battery negative post, so I'm not sure this would make a difference.
64fury74charger
Well-Known Member
You’re definitely on the right track and at least the lights are working which means that the issue appears to be getting a solid ground. Once you test everything and it works then you can sort out the wires and move on to the next step. Anything electrical needs a clean power and a clean ground.
JR_Charger
Well-Known Member
Brake lights work. Lights are plenty bright! I suspect the flasher may have died. It is 52 years old. For the money, might as well replace.
I think I need to run a ground for the license plate light. I thought the reverse lights would be grounded though, if the bezel is grounded. That's weird.
IIRC there are two identical connectors in the wiring harness, behind the license plate. 50/50 chance I have them plugged in backwards.
I think I need to run a ground for the license plate light. I thought the reverse lights would be grounded though, if the bezel is grounded. That's weird.
IIRC there are two identical connectors in the wiring harness, behind the license plate. 50/50 chance I have them plugged in backwards.
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JR_Charger
Well-Known Member
I tried touching the ground wire to the socket for the license plate light. Nothing. I'd like to check the bulb, how do you get the screws out of the light cover? Maybe I can hold a phillips head bit with some needle nose pliers - but surely that's not how it's supposed to be done.
JR_Charger
Well-Known Member
Got the license plate lamp to work, problem was bad bulb and no ground.
No ideas on the back up lights, unless the reverse switch has gone bad.
No ideas on the back up lights, unless the reverse switch has gone bad.
JR_Charger
Well-Known Member
Strange problem with the tail lights. Three are working right. The fourth lights up like the brake pedal is pressed, when it isn't; but when the brake pedal is pressed, it dims.
Put a new flasher in, still no turn signals. I hope all these grounding issues didn't burn out something in the new turn signal switch.
Put a new flasher in, still no turn signals. I hope all these grounding issues didn't burn out something in the new turn signal switch.
JR_Charger
Well-Known Member
The emergency flasher works - it dims the interior lights when it flashes, but that function works. So why no turn signal?
JR_Charger
Well-Known Member
All four tail lamps work good now, except for the turn signal function, which doesn't work.
I'm focusing on the reverse lights. No power is getting to B2-18V -
It looks like B2-18v runs back to the part of the fuse block labelled "bk-up lamps." I'm only getting power to one side of the fuse. I've pulled the fuse out and it tested good, and looks good. Are there any other conditions that would cause it to be lit on only one side?
Should that fuse be seeing any power with the car in "park?"
I'm focusing on the reverse lights. No power is getting to B2-18V -
It looks like B2-18v runs back to the part of the fuse block labelled "bk-up lamps." I'm only getting power to one side of the fuse. I've pulled the fuse out and it tested good, and looks good. Are there any other conditions that would cause it to be lit on only one side?
Should that fuse be seeing any power with the car in "park?"
JR_Charger
Well-Known Member
All four tail lamps work good now, except for the turn signal function, which doesn't work.
I'm focusing on the reverse lights. No power is getting to B2-18V -
View attachment 1587402
It looks like B2-18v runs back to the part of the fuse block labelled "bk-up lamps." I'm only getting power to one side of the fuse. I've pulled the fuse out and it tested good, and looks good. Are there any other conditions that would cause it to be lit on only one side?
Should that fuse be seeing any power with the car in "park?"
edit - It should be seeing power on both sides at least, and does with a good fuse
Turn signals work now. I had replaced the flasher for the hazards instead of the one for the turn signals. I couldn't find my old hazard flasher, so I swapped the two I have around, and now I have hazards and turn signals. Don't know why the old turn signal flasher works fine as a hazard flasher, but it does. I'll replace it anyway the next time I order from Rock Auto.
I'm focusing on the reverse lights. No power is getting to B2-18V -
View attachment 1587402
It looks like B2-18v runs back to the part of the fuse block labelled "bk-up lamps." I'm only getting power to one side of the fuse. I've pulled the fuse out and it tested good, and looks good. Are there any other conditions that would cause it to be lit on only one side?
Should that fuse be seeing any power with the car in "park?"
edit - It should be seeing power on both sides at least, and does with a good fuse
Turn signals work now. I had replaced the flasher for the hazards instead of the one for the turn signals. I couldn't find my old hazard flasher, so I swapped the two I have around, and now I have hazards and turn signals. Don't know why the old turn signal flasher works fine as a hazard flasher, but it does. I'll replace it anyway the next time I order from Rock Auto.
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