ppinto

Hello,

I'm new to the forum.

I have a 2006 Cayman S. Last night I got a brake light warning, and changed the bulb on the corresponding side (which was out). The new bulb didn't light and the warning remained.

I put the original bulb back in, but swapped the sides. The bulb works fine on the opposite side.

I removed the bulb assembly from the offending side, cleaned the contact surfaces on the bulb and assembly with a magic eraser, and retested. The problem remains.

Has anyone seen this? Any suggestions?

Thanks.

TMc993

Have you checked the fuse for that circuit? There is one for each side. If it's blown, you'll need to determine why. If it isn't blown, remove it, clean the contact surfaces on both the fuse and the fuse box and then see what you've got.

ppinto

Thanks for the suggestion, TMc993. The fuse looked okay, so I swapped it with the right side to test. I'm getting the same result: no function from only the brake light on the left side - with a corresponding warning indicator for exactly that condition.

Could this be a bad controller of some sort? I cringe to think how much that would cost.

jscott82

The controller for all of the rear electronics is under the drivers seat, I would be stunned if it were actually the controller though.

I just redid that whole section of the wiring harness in my SpecCayman, so pretty familiar with it... Controller is under the seat, harness goes directly back behind drivers seat, along the rear quarter panel to the fuse/relay connections in the left rear quarter, then on to the lights... Its one harness, and pretty simple/straight forward.

ppinto

jscott82, thanks for your reply. So, there's another fuse block in the left rear quarter? I swapped the left/right fuses in the driver's kick panel. If I read that correctly, where exactly is it? Thanks!

jscott82

Left rear quarter, tucked behind the wheel arch... Its been awhile since I pulled the interior so don't remember what you have to remove to get to it.

I have the schematic at home, Ill post later tonight when I get home... But I doubt there is a fuse or relay between the controller and the bulb, just that the harness passes through that area. The controller would want to "see" the bulb directly to interrogate its health..

jscott82

Wireing Diagram

TMc993

I thought there might be a test procedure for the control module but can't find one anywhere. Obviously, the bulb isn't getting juice through it and on to ground. Any chance there is a bad ground wire on the left side tail light that isn't doing it's job? To be clear, it is only the brake light not illuminating on braking? The turn signal, running lights, and reversing lights all work? Or, is it the entire, left side unit?

ppinto

TMc933, thanks much for the schematic. There doesn't seem to be anything besides cable and connectors between the controller and the bulb.

All the other lights on in the assembly are working fine. Based on the schematic, they seem to be fed by a common ground - so I don't think that's the issue.

I suppose I could try wiggling the connector in the controller? I'm at a loss.

TMc993

Can't take credit for providing the schematic....That was courtesy of jscott82.

If it were me, on the chance that something random needs to reset in the controller, I would disconnect the battery, let it sit for about 10-15 minutes, then reconnect and see what you have. Also, while looking for info on your issue, I did see some references to fault codes thrown by various Boxster and Cayman controllers....Didn't look further because I got popped with a couple of malware alerts on those sites.

I know nothing about code readers for your car, but if you don't have access to an appropriate one, it may be time to let a shop look at it. Sorry I couldn't be more help.

User 52121

Hey @jscott82 - any chance you have a slightly bigger version of that? It's a little hard to read.

I have a similar issue with my car - but it's complaining about the CHMSL. It's connected and it works - but the error is still there. :/

The wiring in my car was totally hacked up (not by me) so I want to be able to trace everything and see what's what.