Electrical system maintenance

[youngbimmer]

Around this time last year, my beloved 735 had an electrical fire and burned itself up. Since nothing mechanically speaking really goes wrong with M30 based cars, I’ve turned my attention to electrical maintenance on my replacement car. Would it be prudent to replace all the fuses with new ones, scrub the relay contact pins with steel wool/Emory cloth + contact cleaner, and use contact cleaner on all the module pins like CCM, LKM, etc. I do not want a repeat of last year. My battery has the vent tube attached, blower motor fuse was already changed to 20A from 30A, any other fuses that should be replaced with lower rated ones?

[shogun]

That is basically enough, blower motor fuse I would even leave as original. But do not forget the fuse box under rear seat, check carefully the fuse and contact pins for the rear window heater and antenna, rear window heater caused some problems around the world on E32, while I only hear about heater blower motor probs in the US. all on my website: Diagnosis - Fires http://twrite.org/shogunnew/diagnosis/fires.html
check the thick wire between alternator and B+ pole, especially on 750 that is a prob, pics are on my website, I replaced it DIY.
Also check the wire looms in engine bay, in case something is brittle, take care of it. Tesa has a Wire Loom Harness Tape used By Mercedes BMW VW Audi, quote:
Big 19mm X 25m roll
• Matches other wire looms in your car
• Genuine German Quality
• Good adhesion
• Gives professional appearance
amazon, ebay etc from $ 5 or so.

How to DIY - wiring harness restoration https://www.youtube.com/watch?v=yvS3D2TOucs

I have also replaced most of the plastic wire loom connectors in engine bay, they are all very brittle.

[youngbimmer]

Where is the best place to source the electrical connectors? Mine are also brittle, I would like to replace with new plastic ones. Process is to cut the old, strip wires, join the two with new butt connectors yes?

[shogun]

I bought them all from BMW
https://www.realoem.com/bmw/enUS/par...BMW-735i&mg=61
for connectors, best but expensive are the watertight connectors, that is the connector with a piece of wire already connected
https://www.realoem.com/bmw/enUS/sho...diagId=61_2654
https://www.realoem.com/bmw/enUS/sho...diagId=12_1592
BMW breakout boxes and connectors (PDF) http://www.e38.org/breakoutboxesandconenctors.pdf

[Zej]

Don't forget the alternator cables. I think it was the alternator to +'ve terminal on my last 750iL that caused it to immolate itself many years ago.

[shogun]

Alternator to B+ I already replaced 10 years ago DIY with flexible welding cable and oil and heat resistant coating/sheath , pics on my website. But that is mainly a risk for owners with M70 engine, but better to check on the M30 too.