Plate Lights are Out, Looking for Ideas

[machone]

OK, first post - I've searched the forum for an answer, and didn't find anything applicable -

Just bought a 1999 986 - the car is in great shape, except the license plate lights are not working. I removed the bulb holders from the bumper and replaced the bulbs - the bulbs looked bad, and I assumed that was the problem.

Still don't have either light working. I've checked the fuse, which I believe also operates the gauge lights (which are working). Has anyone encountered this problem before? If I have to, I've found the instructions to remove the rear bumper and chase the wiring harness (which I assume could have come unplugged).

Any ideas? The car has never been reported in an accident, and I can't see any evidence of bodywork, so I don't believe the bumper has been apart recently.

Thanks.

[Kirk]

If you've got a multi-meter I would double check the ground for continuity to the body of the car and check for voltage. If you've got ground, then the wiring harness is probably connected. If you don't have voltage, then I'd double check that fuse. Some of the MOST confusing problems I've had are from light bulbs and fuses that looked good, but actually were not.

If you have neither voltage nor ground, then I would take the rear bumper off to see if it got unplugged. Maybe someone removed the rear bumper to install an exhaust and forgot to plug the lights back in. It's easy to forget and would go largely unnoticed by most.

If you don't have a multimeter, then buy one, borrow one, or go to an autoparts place like AutoZone where they rent them for free. Usually you can check for resistance (ohms) and there will be a setting to check for continuity (the meter beeps if there is an electrical connection). There should be continuity between the negative lead on the bulb socket and the car's metal body.

Kirk

[Jeph]

I'm not certain if this matters, but before you try anything drastic, start the car then turn on the lights.

Basically, check the lights while car is running.

[machone]

Good idea, thanks Kirk.

I see from the wiring diagram that the plate light is grounded to Ground #8, which shouldn't be too hard to access in the trunk.

[Westwood]

I second the unplugged theory. When I bought a 996tt a couple of years ago I took it in for the 15k check and they discovered it was unplugged with their scan tool.

Roger

[Kirk]

Originally Posted by machone

Good idea, thanks Kirk.

I see from the wiring diagram that the plate light is grounded to Ground #8, which shouldn't be too hard to access in the trunk.

You don't need to specifically find Ground #8. Maybe you know this already, so please excuse me if I'm telling you something you already know:

The whole car body is part of the grounding system for electrical components. I was suggesting then that you just check continuity between the negative (ground) lead in the bulb socket to the car's body somewhere (the trunk latch hardware should do). That will tell you at least if the harness is unplugged.

Kirk

[Tool Pants]

Is this a Canadian car?

[Lil bastard]

Originally Posted by Tool Pants

Is this a Canadian car?

My thought too... that would mean it has a different fuse for the license plate lights (A8 instead of A5), and being so close to the border (MA), I wondered about this also!

[machone]

Carfax has the car as delivered to New Jersey - how would I identify if was Canada-spec?

Originally Posted by Lil bastard

My thought too... that would mean it has a different fuse for the license plate lights (A8 instead of A5), and being so close to the border (MA), I wondered about this also!

[Tool Pants]

The only reason I asked if it was a Canadian car was because the spec for that country have day time running lights. When those cars come to the US some people pull the relay. Then after that, sometimes the license plate lights do not work.

There is a sticker on the door. There is also an option sticker and C36 is for Canada.

If you do not have a Canadian spec car with the relay pulled, then you have something else going on.

But for all I know, your rear bumper cover was replaced, and the connector not hooked up.

[machone]

Thanks to everyone that responded.

Finally tackled it this morning - used a multi-meter to confirm that the lights were unplugged prior to removing the bumper cover.

Found the bumper cover surprisingly easy to remove - there are some pretty good instructions on this forum, but I found the pictures in the Bentley manual very helpful.

Plug was hanging in the bumper cover - plugged it back in and both lights worked. Wire-tied it together just to avoid this happening again, and replaced the bumper cover. Need to pick up a couple plastic rivets for the spoiler cover, but other than that the repair is complete.

Repair #2 done (also replaced the cigarette lighter with a standard dimension one) - now to save up for the Litronic conversion kit....

Originally Posted by Kirk

You don't need to specifically find Ground #8. Maybe you know this already, so please excuse me if I'm telling you something you already know:

The whole car body is part of the grounding system for electrical components. I was suggesting then that you just check continuity between the negative (ground) lead in the bulb socket to the car's body somewhere (the trunk latch hardware should do). That will tell you at least if the harness is unplugged.

Kirk

[Kirk]

Originally Posted by machone

Need to pick up a couple plastic rivets for the spoiler cover, but other than that the repair is complete.

FYI, I tapped those holes for the spoiler cover and installed some allen head bolts to hold it in place. I've had my rear bumper off several times (installed an aftermarket one) and have always been glad I did this. There's not much "meat" to tap into, but the bolts only need to hold a plastic cover, so they don't need to be heavily torqued. Clearance to the rear trunk should be gauged carefully too.

Kirk