jfrahm

Yikes, your short probably killed the old bulb module.
To find the short you need to isolate sections of the harness. A rude old trick though is to hook up the circuit with a larger fuse or no fuse and look for the smoke. IMO it is better to start by being logical about where the short might be and look in those places. That would lead me at first to the corner lamp assemblies and the bulb sockets.
Take your corner lamp circuit boards out and check 'em out on the bench, also check your fuse and center lamp operation with these out. Divide and conquer. I would expect to find a bad situation shorting one of these sockets since a human can go in and mess around with these assemblies and bulbs are inserted and turned and something can always go wrong with that sort of thing. Apes in the plan.

Progress though!
-Joel.

hillpc

I love it; made my morning! That must have been what the previous owner tried, killing one circuit in the module and melting the brake light fuse position in the fuse block.

If I'm not mistaken, the short is not in the corner brake lights because they work fine, and use different wiring all the way from the module than the middle brake light does. If I can get under the "hat shelf" without too much trouble (that remains to be seen), where I should be able to access the middle brake light wiring, it might be fairly easy to install a new wire all the way from the module, under the rugs and back seat, and then up behind the seatback to get to the connector at the light. It looks like a real bear to try to follow the existing wiring after it leaves the module, where giant bundles disappear into the bowels of the car.

jfrahm

If it's not shorted at a corner lamp odds are it's shorted near the CHMSL itself where something could rub or damage the wiring.
Could be some part of the stereo or aftermarket stuff was installed and screwed into the CHMSL wiring or in a way as to crimp it.

hillpc

Getting closer - the hot and neutral on the way to the CMHSL shorted across with insulation melted, right at the wiring connector behind top passenger outside edge of back seatback. There are no obvious signs of sparked metal near there that would be a smoking gun. Also, the power sunshade won't run down the last half inch or so, chattering and jerking for about 2 seconds till the controller shuts the motor off. The stop light wiring runs right underneath the motor, so I wonder if it somehow got caught in moving parts of the sunshade mechanism . As long as I'm this far in, I might as well fix the sunshade, and get the last 2 foot length of wire out in the open. But I'm having a hard time getting the hatshelf out. "Raise shade box so screws are released from hatshelf." Huh? Shade box? There are also 3 child restraint anchorages, and 2 speakers, that seem to be holding the hatshelf down tightly. I suppose I could fish a new wire and leave the sunshade alone, but I hate to let stuff get the better of me.

hillpc

Both the speakers and the child seat anchors were holding the hatshelf down. No mention in the Bentley.

hillpc

Replaced about 4" of the melted wire by cutting near the connector and soldering in new. I never did find out what caused the original overheating. Works fine now, with the new (used) module. I couldn't figure out how to stop the power sunshade chattering after retraction, so I put it all back together. Started a new thread on the sunshade; nobody has commented yet. It's a minor annoyance when I put it back down.

Thanks again, Joel for your experience.