Wiring harness failure

[Petr Kunc]

Hello everyone,
as promised, I'm putting here the pictures of the harness. It's a complete central harness that has to be changed in its entirety. You will notice that only the brown, hence grounding cables are melted. None of the power cables are damaged.

 

[Scott Semone]

I like that BMW is consistent with using the brown color for the ground; it's easy to remember: BROWN=GROUND

I may try and remove some of the plastics and such, in order to find this bundle of ground termination points and apply no-ox (no oxidation) to the terminals and ground connections; especially the grounding points that would be exposed to wet weather.

When these ground connections become poor, corroded and or highly resistive, current goes up... the return current will also use other paths of least resistance in order to complete the circuit. Poor grounding can lead to other components to be electrically overstressed, resulting in faulty and or unexpected performance of devices.

i.e. A poorly grounded stereo system, can potentially use the physical ground connection that is typically made where the antenna is mounted on the roof of a vehicle, where the antenna ground plane becomes the path of least resistance via the outer coaxial cable leading between the stereo receiver and the antenna connection. Depending on the required current load of the system, the alternate path of using the antenna coaxial cable may electrically overstress components in the receiver section... WOW.. that was a long example explanation....(sorry)

 

[Petr Kunc]

I like that BMW is consistent with using the brown color for the ground; it's easy to remember: BROWN=GROUND

I may try and remove some of the plastics and such, in order to find this bundle of ground termination points and apply no-ox (no oxidation) to the terminals and ground connections; especially the grounding points that would be exposed to wet weather.

When these ground connections become poor, corroded and or highly resistive, current goes up... the return current will also use other paths of least resistance in order to complete the circuit. Poor grounding can lead to other components to be electrically overstressed, resulting in faulty and or unexpected performance of devices.

i.e. A poorly grounded stereo system, can potentially use the physical ground connection that is typically made where the antenna is mounted on the roof of a vehicle, where the antenna ground plane becomes the path of least resistance via the outer coaxial cable leading between the stereo receiver and the antenna connection. Depending on the required current load of the system, the alternate path of using the antenna coaxial cable may electrically overstress components in the receiver section... WOW.. that was a long example explanation....(sorry)

At least they are not like French (no offense) with only grey and yellow everywhere But what you just wrote is what I and the BMW mechanic think. The brass ring created a transient resistance and thus increased the temperature.....