Longest Lasting Wiring Harness - w124 - Thread
 

I'm curious to see how long w124 owners have been able to remain on their original wiring harness. Plenty of Mercedes people / mechanics have said "its when, not if," but how long can it go?

Ours: 1995 E320 wagon, still on original harness, some flaking / cracking, but no issues, 125k miles, 17 years old.

Post your w124's year and current mileage if still original, or age and approximate mileage when yours failed.

My 500Es upper harness was done around the year 2000-2001 at about 110K miles. It prolly should have been replaced a year or so before that too. Now the car is at 157K miles.

Anyone with an original harness at this point is well beyond borrowed time ! :)

My '93 500E harnesses were done in 6/11 @ 140k.

1993 300 E (2.8) 234K miles. Original harness

This car is amazing.

Well, it looks like some of these things can last awhile. Probably climate has an influence. Hot summers and cold winters should speed up harness deterioration. At 19 years and 234k miles, I think Martin has the record so far! Let's keep the numbers coming!

1992 400E : 20 years and 266,786 miles.

1993 400E: 14 years/200,000 + miles.

New record holders! 400E is a great car.

They can last a long time if you never touch the wiring. One it's flexed, such as for a head gasket change, the insulation spalls off and you're practically guaranteed to have bare wires touching each other. Anybody who has removed the armor on the wire bundle and flexed the wiring knows what I mean. The insulation basically turns to dust.

While I generally agree with Kestas' comment, I will say that our E320 has had the head gasket replaced twice now for oil leakage issues...once at around 80k and once at 120k. The harness did survive.

It's a little touchy when it's raining. Never does the same thing twice. Just minor hiccups though. Also will miss sometimes and then it will run perfectly when it warms up a bit. I cut the outer wrapping on the two wires going to the two-prong temp sensor, and they are bare, with little bits of insulation falling out around them.

Do the wiring harnesses degrade as a function of age, or of use (mileage)?

1990 300E.....still original harness, not in the best of shape, but no malfunctions so far....

The wiring harness insulation degrades from age and heat. There was a report that a Florida car showed this problem after two years service and was fixed under warranty.

We had to wrap these wire ends with electrical tape...at the very end where the wires come to a plug on top of the water pump. This connector controls electric fan speed. Unplug it and the fans will run on top speed all the time.