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Renewing the wiring on a Mercedes. Mercedes like many manufacturers design the wiring to be biodegradable. After 10-15 years the insulation starts to breakdown. This is not good news to anyone with a classic car. Some symptoms… voltage drops in supply to electronic systems. P0221 which after investigation has nothing to do with parts. Its because of the error in voltage to the ECU.
Would love to know your thoughts.
Jane
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I’m not saying your wrong, but Mercedes is the only company I’ve heard of that uses biodegradable wiring… Now I know sometime ago Honda talked about biodegradable seats and things, but as far as critical components go I’ve only heard of Mercedes using it… But all cars after 10-15 years have some wiring trouble, especially is colder states, but that’s not due to biodegrading…
SAAB and Volvo were suffering the same problems; biodegradeable wire harnesses. As a matter of fact, I can cite 2 examples of personal cars.
One was an ’85 SAAB that developed starting and running pecularities. Every test in the book done repeatedly showed no problems at all. Eventually I determined the wire harness was degrading by slicing open the protective sheaths with a razor blade. The insulation on the individual wires was bleaching white and would crumble under the fingers; even with the lightest touch.
Another example was an ’88 SAAB I bought as a parts car on the cheap when a long time, respected foreign car shop could not get it to run after throwing every part in the book at it including a new ECM.
I’m also aware of, but did not personally see it, a Volvo of similar era and located in this area that suffered a rotten (biodegradeable if you will) wire harness.
The problem? Wire harness rotting inside the sheaths.When this happens there is no way of determining what wire is touching what or when it will happen.
Here is an example of a wiring loom degrading… This is a design feature common to all manufacturers.
Corroded copper doesn’t conduct. So the more oxygen in the copper the higher the resistance. = Voltage drops.. PVC insulation starts to breakdown around about 10 years. This lets oxygen past. This then starts copper corrosion. We used to keep wiring looms in boxes in the parts department. Even without getting wet the insulation after 30 years had turned to dust.
Manufacturers thereby are sure your going to keep buying new cars. It’s the same reason Delorian cars never got off the ground. “Stainless steel cars… They will put us out of business”…
Helpfully
JaneTrue enough. With the rotted cars I dealt with the sheath could be cut open way back from any connector, the insulation crumbled off, and the copper wire would actually be black or dark gray in color.
My understanding is that the biodegradeable harnesses came about because the Euro people were trying to be environmentally conscious, prevent rats and mice from eating wiring in the boneyards, and so on.
Unfortunately, degrading while you own and drive a car presents problems. I owned a SAAB that went through this. The engine was developing a bit of a timing chain rattle and when the wire harnesses started crumbling I just parted the car out rather than invest a ton of hours in repairs. The timing chain is a nightmare on its own and coupled with replacing who knows how much harness it just was not worth it.
I know that every piece of the harness I cut open showed nothing but bleached wire insulation that was turning to powder. Pathetic.
Both of the cars I have owned was more then 10 years old and didn’t have any problems related to the wiring or wiring harness.
Mind you both of them were Japanese 😛
I don’t know much about the Japanese Cars wiring. However, I suspect from experience working on Toyota trucks, that the wiring insulation will eventually breakdown. One Toyota truck it wouldn’t start? On investigation it was found that the wire leading to the starter solenoid was corroded right through. This Was near the oil filler for the engine. Did the oil ‘perish’ the insulation I can’t be sure.
If you have had similar experiences let us know?
Jane 😉I have done so many engine wiring harness on Mercedes it is a joke. all Mercedes have the problems from the v12 to the 4 cyl model year from 1994 to about 1998. the v12 payees the most about 6hr but can be done in about 1.5hr if you know what your doing. the may thing is that I have seen a wiring harness take out a engine control unit many times so your looking at a 4,000 repair. but at the end of the day if you want to play you have to pay.
[quote=”Inverlass” post=68621]I don’t know much about the Japanese Cars wiring. However, I suspect from experience working on Toyota trucks, that the wiring insulation will eventually breakdown. One Toyota truck it wouldn’t start? On investigation it was found that the wire leading to the starter solenoid was corroded right through. This Was near the oil filler for the engine. Did the oil ‘perish’ the insulation I can’t be sure.
If you have had similar experiences let us know?
Jane ;)[/quote]I have seen very few such issues with Toyota wiring harnesses… Frame/rust issues… sometimes… but not wiring… And one such as a solenoid wire corroding, well that could happen to almost any kind of car that has a starter on the bottom where I live in the rust belt….
Most wiring/electrical issues I have seen are on European cars…. Nothing personal, but I don’t like working on them…. chasing down a charging short and headlight shorts in a few VW’s that seemed to use single strand telephone gauge wire was enough for me….
JMHO
-Karl
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