from Pete in U.K.
Rear seat started to smoke - fortunately there was no open fire
The problem was the rear window defroster -- the defroster is driven by a relay in the LKM.
In his case the relay stuck full on and the heavy current drain of the rear windowdefroster overloaded fuse 35 in the rear power distribution box
OR the defogger relay k13 (see diagram below, inset 3)
The defroster circuit is designed to operate only for a short time then switch off automatically.
This problem is difficult to prevent since there is no indicator that the relay has become stuck on!
Fix: repair the LKM module and of course all the stuff under the rear seat

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E32 and E31 M70 models have a reputation for engine room fires.
The cause is failure of the insulation on the heavy power cable from the alternator to the + terminal post.
Two faults are possible: the cable corrodes which cause high power drop at the corroded part with then turns into an arc welding machine
OR the cable touches some metal part and then turns into an arc welding machine
First the cause then the result Fix is here

this is the cable from Shogun's trusty E32


this E31 owner did not check his cable soon enough

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