All rear lights suddenly out

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1991 jetta
Was driving home last night, cop pulls me over for no tail lights.
I got a ticket that can be voided if I fix it.

He said I had no tail lights, no license plate light, nothing.
Brake lights were working as well as turn signals/hazards.

Well I drove a few miles further toward home, pulled over, got out, and they were all working.
This happened once before, so Im not accusing the cop of being dishonest.
99.9% of the time the lights work fine, so it's not easy to find the problem.

So obviously I have bad connection somewhere, but Im trying to narrow down my search. What would cause all lights on the back to go out, but not brakes or turn signals? Is there a ground for just that circuit? If not, there must be one power wire that supplies all those lights.
Just looking for ideas. thanks

[82vdub]

There are likely a ground connection at the back of the car. However, I'd look at the Bentley manual and trace those wiring circuits that are all out and see where they come together to find out at what point to try to start troubleshooting where you may have a loose connection. There will be one main wire running to the back of the car for the taillights etc, but if the taillights and front marker lights go out at the same time, it's not the line running to the back of the car. So, it would be somewhere in the circuit before the front and rear wiring harnasses split the circuit running to those items. One of the culprets that causes issues from time to time is the ignition switch. You could probably rig up a light, or 12V gauge that's energized when the rear taillights are operating. This will tell you if they go out after you've turned the key on, or if they don't light up when you turn the key on (short based on jiggling of a connection or maybe a bad connection). This would allow you to also determine if the front marker lights also go out when the rears do or not.

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The front markers were working the entire time, only the rear lights went out.

Good idea on the indicator light.

[82vdub]

Ok, that should give more direction on where to look at. It wouldn't be with the ignition switch and where does the power feed split to go to the front and rear. Sometime after that split, or at that split.

[Prairieview]

Well, several years ago, I purchased groceries at a big store that has a free-standing liquor store right next to it. I don't even drink....really ever. I put my groceries in the trunk of the Jetta and left the parking lot. A couple blocks later, these two young cops pull me over and tell me the tail lights are not working.

I ask them if I can get out and look....and, SHAZAM....the lights are on just fine. Frankly....this is an old cop trick which they employ when they want. I have NEVER had any issues with lights before or since. Do you get what i am saying?

Do as stated above (previous posts) with the grounds, etc. But.....this is an old "trick" they employ....just so you know.

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Yes I know of the "old trick", and that is why I mentioned that the cop was honest in this case.
He didnt ask to search or even look in the back seat.

I know that my lights were out last night, and as I said, it has happened before (lights randomly going out, never been stopped for it before). Its just so intermittent that its difficult to trace down the fault.
I was hoping maybe somebody had the same experience and could save me some time.

[JHH]

Yes, it's for real if they issue a ticket for it. Could be as simple as a flaky fuse. If you're working alone like I usually do, try to get backed up to a glass storm-door or something to use as a mirror while you work. Wiggle the fuse, jiggle the switch, jimmy the wires, all that sort of thing. Intermittent problems are tricky, but eventually, I'm sure you'll find the problem.

In the mean-time, go to the auto parts shop, buy a fuse, get the receipt, and take it and the ticket to the police department or Sheriff's office. I've done that before. A five buck fee is better than a hundred bucks in court-costs.

Good luck.

[TylerDurden]

Mk2 Jettas have a ground attached to the center support under the trunk latch. It can easily corrode due to its location. A pinky-bet says you clean that connection and enjoy reliable tail lights.

I got caught in one of those near-whiteout storms this winter behind a car with headlights but no tail-lights... got past him AFSAP.

[Fatmobile]

My '91 Golf had this problem.
Ended up being the headlight switch.
Common problem,.. I thought about relaying them so I don't have to buy a new switch again soon.