I've redone a few of the crumbling harnesses on mine...but I've actually been able to remove the terminal ends at the boot(s) and recrimp the leads on all new wiring, then re-loom the bundle.

On terminals where this wasn't possible, I soldered the leads and used heatshrink tubing, then insulated electrical tape.

I agree that soldering is the best method. I've seen from experience, non-soldered leads corrode over time, causing problems.

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car