I'm away from home for a few weeks visiting grandkids and my heater started working only sometimes (85 300sd). Since it's cold my wife doesn't think that's often enough. Would someone link me to the wiring diag? Also, I don't remember how the wood trim comes off, anyone? I remember (I think) that the ashtray comes out, then the radio and somehow the wood in front of the ccu. I'm going to start with solder connections since it heats OK sometimes and other times not at all. Thanks for any help, Jim

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85 300 SD ~ 115K
82 500 SEC Euro ??K
78 450SL 164K

The full wiring diagram is a bit elusive to obtain. There are some decent schematics in the climate control manual, but I don't think you'll be able to troubleshoot at the component level with them.

To remove the wood trim, remove the ashtray and the sliding chassis for the tray. Then underneath the trim are two phillips screws that hold it in place. The are installed from the bottom........vertically upwards.

Slide the trim downwards about 1/4" so the top clears the dash and pull it toward you. Disconnect the plugs to the CCU and the five plugs that are attached to the switches. The trim is then fully removable with the switches attached.