I have been doing quite a bit of 'research' the last few months since I bought a 94 SL-600. The main engine wiring harness was replaced before I would drive it--bare wires all over the injector harness. I have since 'learned' that MBZ (and BMW and Volvo and Audi) has a BIG, but hidden problem with many of their cars dating back to the early 90's.

Lots of wiring harnesses are failing, lots of components too. The insulation on the wires in some wiring harnesses just crumbles to bits. When hidden in a bundle, inside a covering, it isn't noticed and the crumbs still keep things from shorting out. Then the bundle flexes (from work on something, or vibrations, it then fails immediately or soon thereafter.

Some have been replaced under warranty, but most are still out there and failing by the droves. Replacing the main harness in a 129 or 140 is over 25 hours, plus the harness!

All/many ?? of the electronic throttle actuators have the defective wiring in the cables from the plug to the unit.

I am asking members to post wiring harness related problems. This is a lot more pervasive and costly problem than I had expected.

My car just 'quit' into limp mode in the middle of an intersection and I nearly got broadsided. All the insulation on all the wires to both throttle actuators was toast crumbs. Wiring inside the actuators (different insulation) was like new. It fried the electronic accelerator module when it failed too. And there are no exchange/rebuilt parts available from MBZ.

This smells like a safety related coverup. Ford got hit with very large judgement for a lot less serious and much less costly to fix common mode failure recently.

Is this a class action lawsuit in the making!!! Smells like it. These kind of failures are not normal wear and tear, and ARE big safety defects.

You should do a search on WIRING HARNESS and you'll come up with quite a bit of info on how Mercedes-Benz (/dealers) are handling the situation.

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

You're right. A lot of the engine wiring harnesses are crumbling and especially after you do some work like a head gasket job etc. I've replaced probably a dozen or so and the most I was paid was 3 hours. It only takes 1. 25 hours for an engine wiring harness it outrageous. Did I misunderstand you maybe?