Tail lights not lighting

[octobersknight]

I checked and didn't see a thread on this, so I thought I'd post something. I've completed the wiring for my rear lights and everything finally works except the tail lights. The bright filament works when hitting the brake, but the dim filament does not light when I turn on the headlights via the column lever. I have not hooked up any of my front lights yet to confirm if the headlights at least work ... that's next on my list to at least try. I haven't yet gotten a chance to look through the wiring diagram.

I have tried my taillights with the engine off and with the engine on. Same result.

Any advice?

[aquillen]

The socket pins are notoriously poor fitting - very good chance the buttons on the bottom of the lamps are not making proper contact inside the socket. Also hard to deal with since socket in = can't see what's going on in there. But inspect the pins inside the socket, try wiggle with a pick or tiny screwdriver, see if they are lined up to the bumps on the lamps when they are installed. Very good chance this is the problem IF your wiring is correct otherwise.

[STiPWRD]

I'd check the voltage at the tail light connectors to see if they're getting power. If so, then either the pins are making poor contact with the bulb or the filament is burned out. If there is no power at the connector, then I'd check the wiring and whether you're getting power from the fuse box.
tail-lights.png

[octobersknight]

I finally got around to checking the power at the connector (got wrapped up in starting body work :/). I do not have power at the connector when the lights are supposedly "on" by the rotary switch on the steering column stalk and/or the parking light switch on the top of the column. I also checked the fuse and it looks okay. I have done my checks with the car in accessory mode (not engine running). Does the car need to be running for the lights to light?

Any advice of known problem areas?

Thanks.

[TheHelixx]

I finally got around to checking the power at the connector (got wrapped up in starting body work :/). I do not have power at the connector when the lights are supposedly "on" by the rotary switch on the steering column stalk and/or the parking light switch on the top of the column. I also checked the fuse and it looks okay. I have done my checks with the car in accessory mode (not engine running). Does the car need to be running for the lights to light?

Any advice of known problem areas?

Thanks.

The lights won’t work unless key is set to ignition, not accessory. Not sure if that’s what you meant or not. Do you find 12v in any of the wires in the rear harness?

[RPGs818SNA]

The parking lights are controlled 2 ways: Turn on the ignition, and turn on the parking lights with the headlights stalk switch, or just turn on the Parking Light Switch (Hazard switch). Either should light the rear tail lights. (Both ways require the Hazard switch to be plugged into the harness.) If not, be sure all the connectors under the steering wheel are plugged in. If still no power to the tail lights, here’s the path the power and tail light relay control circuit takes.

The power for the tail lights goes through 2 fuses, 1 switch, 1 relay, and 8 connectors:
Main fuse box Fuse No7 20 A, connector F68 Pin 4
Fuse and relay box Tail illumination relay, control circuit must be active, conn F40 pin 9, B152 p12, B158 p5
Parking Switch (Hazard switch), B69, pins 1, 2, 4
Fuse and relay box Fuse No 5 10 A, B152 p11, 10
B99 p17, R3 p 17, R28

The control circuit for the tail relay goes through 2 fuses, 1 switch, 1 relay, and 7connectors:
SBF-1, 120A
SBF-4 50A, F38
F46 p2, B108 p2, Ignition switch ON or START, not ACC, B72 p1,4
B158 Pin 8, Tail relay coil, B152 p2
Light switch PARKING or HEADLIGHTS, b71 P14,16, to ground.

Here are the relevant schematics with red for normal tail light power, green for the relay control, and orange for hazard switch power.
Parking lights schematic.jpg

Good luck, and hope it's an easy one to find.
RPG

[octobersknight]

RPG, Helixx, thanks. I'll start digging through my connectors and relays this week. I did mean ignition and not just accessory mode. Just used my long weekend fixing up the truck - front lower ball joints, trans fluid/filter, oil & filter, etc. Tried changing the trans fluid cooler lines but those suckers are rusted in place. Anyway, back to the fun car!

[octobersknight]

Okay yesterday was nice outside so I got sidetracked installing gutter guards before the fall leaf explosion. Still one gutter to do but it's the least troublesome. Hopefully I'll get the chance to track wiring tonight after I cut some holes in the rear bumper and spray some bedliner.

[octobersknight]

I tried my headlights and those too aren't working. I also noticed that my dash display doesn't change with/without lights. So perhaps my switch on the stalk is bad, or I don't have something connected correctly.

Does anyone have a picture of B72, or know roughly what's located near it on the harness? This is a long shot because everyone's layout in the car is different, but I thought I'd ask. I've already searched for the "easy" and "medium" reachable areas of the harness. I'd rather not take off the floor pan, seats, and inner firewalls to hunt if I can avoid that.

[STiPWRD]

B72 is a blue 4 pin connector that plugs into the ignition switch on the steering column.

[RPGs818SNA]

Here's a photo of B72, which is the grayish blue one plugged into the bright blue one about 10 inches from the ignition switch.

B72 photo.jpg

[octobersknight]

Thanks all! I will have to look for that connector tonight because I'm 99% sure that's part of my problem.

[Ducky2009]

Check where the main harness plugs into the rear harness. I had two wires reversed in the plugs. Tan in, green out, when plugged together.
Good luick

[octobersknight]

Well the B72 is plugged in correctly, though I want to verify the pins and wires are seated right. I don't like how much weight/stress the rest of the harness is putting on that. I wish the layout was different or that I had figured out a way to adjust it. I guess I'll have to make some support for it for my own peace of mind.

I'll continue chasing down the line. I like the suggestion about the front-to-rear harness (I'm assuming B99 to R3). Any idea what those look like or where they are? I found B1 and B2 recently but B3 wasn't nearby.

Thanks all for the input!!

[RPGs818SNA]

B99 and R3 are whitish connectors about 2 inches long and 3/8" wide (going from memory here) and were about 2 feet to the rear of the fuse boxes.

B99.jpg

You might also check to be sure the hazard switch is plugged into the harness.

Best of luck finding the issue.
RPG

[octobersknight]

Thanks RPG. I'll continue the hunt. The hazard switch is plugged in and verified operational. That's one item off the checklist!

[RPGs818SNA]

Here are a couple more items for your check list.
Verify that the three connectors under the steering column are firmly seated in their sockets.

three connectors.png

Can't seem to get a photo of those connectors to upload. I'll try again later.
(Well, I got the photo added, but a little after it might have been useful.)

Verify that the white harness wire on the blue B72 connector has 12v when the ignition switch is OFF.
Verify that the yellow harness wire on B72 has 12v when the ignition switch is turned to ACC.
Verify that the green harness wire on B72 has 12v when the ignition switch is ON.
The white-black wire on B72 connector goes to 12v when the ignition switch is on START, but you probably don’t need to check that.
Those readings will help determine where else to look for the problem.

Best of luck,
RPG

[octobersknight]

WOW. Color me embarrassed. In tracing my wiring and such, I found Connectors B69, B70, and B71 ... lying on the floorboard of the passenger footwell. I was mystified as to where the heck they plugged. Had I unplugged them in my wirie tracing search? I don't recall pulling or disconnecting those three. So to the internet to find the "combination light switch," which revealed the lighting switch stalk had a female connector on its underside. As noted by RPG above, there are three connectors under the steering column (but within the plastic shroud). I never knew those were inside there! Or, rather, it has been so many years since I disassembled the donor that I completely forgot there were some connectors hiding in there that I had to reconnect.

So, unsurprisingly, after I connected those, the taillights worked and the dash dimmed (something it had not done before) correctly. Success!! KINDA ...

However, I still cannot get my headlights to light (power on, but engine not running), and now the brake light function of the taillight bulbs doesn't seem to work. I have to check to make sure the filaments aren't burned out, but I fixed one problem and created another.

Has anyone encountered this before? [Shaking my head at my complete idiocy and hoping someone has advice for this new problem (and don't be too mad about my previous "simple" blunder).]

[RPGs818SNA]

Well, although it was tough to find, the solution was simple. That's a plus.

Here's how I wired my brake lights. (Looks like I can finally attach a photo again.) I used the connector from inside the tail light housing.

brake light wiring.jpg

Connector black ground to white socket ground
Connector brake wire (shown as WB) to the red socket wire
Connector parking wire (Shown as R) to the brown wire

At least the circuit is really simple: battery, switch above brake pedal, couple of connectors, and the brake light.

Hope that's an easy fix too. Then on to the headlights.

All the best,
RPG

[octobersknight]

Okay quick update - most of the mystery is solved! But not all. Sorry for long intervals between updates but I've been working on my hood a bunch and haven't chased electrical too much. Check my build thread for updates on the hood soon.

Back to this. Once I plugged in the steering column plugs, the brake lights and headlights still did not work. I found a loose plug from a fuse box and plugged it in, and voila! the headlights worked just fine (both high and low beams). Brake lights are still not working though. Hopefully I can find the last unplugged connector tonight and solve that for good. I don't have my front turn signal or DRLs in yet to check them, so that will just have to wait.

Current check:
Tailights - OK
Headlights (hi/lo) - OK/OK
Reverse - OK
Rear Turn - OK
Brakes - NO
Front Turn - NOT CHECKED
Front DRL - NOT CHECKED

Any thoughts on brake light power would be appreciated here. I have the feeling that, like the headlights, I just unplugged something somewhere while searching for my taillight problem and just haven't found it again yet. If I had just remembered about the interior steering column plugs, I would have avoided all the undoing of my wiring and all the unplugging that I did, and saved hours of work in the meantime. It'll be worth it though. Gotta love the grind.

[RPGs818SNA]

Congratulations, you're almost done. Fortunately the brake circuit is simple. There are only 5 likely places to check:

Tan fuse panel Fuse #16 20 Amp Blue Yellow wire
Brake pedal connector to brake switch
Rear wiring 8 pin white connector B97 to R1
Wire harness to brake light socket
Black ground wire

Since the tail lights are working, the rear wiring connector and ground are probably OK. That leaves only 3 things to check. Let’s hope you find it pretty quickly.

Best of luck,
RPG

[octobersknight]

I'VE CRACKED IT! Luckily this time it wasn't even me. I did some diagnostic wire checks, including all the bits RPG mentions above, and narrowed it down to the brake switch itself. The performance was intermittent, and seemed to work well in hand once I took it out of the car. I decided to crack it open, and low and behold - the contact pad on one of the connector blades is seriously degraded. Good and bad comparison pics below.

PXL_20230208_003213247.jpg PXL_20230208_003247361.jpg

Time to order a new switch, test out the front turn signals and DRLs, then button up the wiring and center console again. For anyone keeping track, luckily I hadn't cut any wires, made any bad solder joints, or mis-wired anything. I simply hadn't connected all the plugs that needed plugging. Thanks everybody for the assistance!!! If I hit any more troubles (front turn signals, DRLs), I'll pop back on here.

While I had some time, I also decided to crack open the rear turn/reverse connector to get those darn wiggly blades held in place. I just used some 2-ton epoxy, which hopefully holds the blades in place. I'll have to do a little bending to make sure the contacts aren't touching each other with the bulb in place, or I'll get cross-talk again and my turn signal will light for both turn and reverse.

PXL_20230207_215443395.jpg PXL_20230207_215437531.jpg

[RPGs818SNA]

So glad you found it so quickly. Your previous donor owner must have spent too much time with their foot on the brakes. Hope the rest of the wiring goes smoothly.

Those reverse/turn connectors leave a lot to be desired. I did the same things to make them a little more functional and reliable.

All the best,
RPG

[octobersknight]

Another update. The epoxy didn't stick for crap to the coated pin/blades. When I tried bending them so they wouldn't contact each other, they popped loose and one even snapped. So rather than try to fix that I decided to hunt for an alternate solution.

Here's what I found: the socket we want is actually closest to a Volkswagen Beetle (1998-2010) three-pin turn signal socket and the part number is 7D0953123A. This will fit 1157-style bulbs with the offset pins (BAY15D) and not the ones FFR sent us (BA15D). I am picking up a couple sets of cheap ebay LED "switchback" style 1157 bulbs which will give you alternate white or amber. Since these bulbs are non-reversible, I'll have to verify the correct pinout before wiring to make sure I get the correct color. I wish the supplied Hella sockets had all three pins instead of two with the third one just snapped off ... we could have had much better quality sockets and FFR would have saved some money at the same time.

I don't have a way to check if the FFR-supplied connector will fit the VW socket end yet. Probably not, and I'll have to source the wire end next. I'll keep you all posted. EDIT: I just found that the VW socket connects to part 1J0 973 723. I'll source a couple of those now as well.

[octobersknight]

Also - new brake switch and the brake lights work as planned! Front turn signals work as well. I couldn't get the DRL things to work, but I also haven't checked voltages. My battery is at 12.01V, which may not be enough to trigger them. Also, I still have the DRL circuit in the car which drops the voltage further. I may have to trim that to remove the headlight connection to the DRL system so I can then remove the resistor to get full voltage. That is the next check (either before or after the new turn/reverse light thing, depending on free time and when supplies arrive).

Current check:
Tailights - OK
Headlights (hi/lo) - OK/OK
Reverse - OK
Rear Turn - OK
Brakes - OK
Front Turn - OK
Front DRL - NO (need to check voltage at pins)