Wiring Harness Failure

[kamatr]

Model: E220CDI - Nov. 2007

Failure of wiring harness in engine compartment leading to shorting and failure of Fuse 57.

Root cause was the wiring harness rubbing against one of the engine compartment insulation fixing screws spot welded to the bulkhead and abrading the insulation of the engine control unit wire until it shorted.

MB are proposing a repair by "cutting" out the damaged section of wire and soldering in a new section, the joints being protected by heat shrink tubing.

Anyone else encounter a similar situation ?

Would like comments on the proposed repair method; personally I have misgivings with regard to the long term effectiveness of the insualtion properties of the heat shrink tubing and it's weathertightness.

 

[jaymanek]

what is protected under fuse 57?

 

[grober]

The proposed repair should be fine provided the short has not damaged other wire insulation elsewhere in the loom by localised overheating. This is what the fuse is for and sounds as if it has done its job. If properly done and sealed against the ingress of water heat shrink insulation should be fine. Remember we are talking only 12 volts here. Make sure they eliminate the cause of the abrasion that started this in the first place by re-routing the cable and sleeving the insulation screw with a suitable material.
p.s. Since the car is not yet a year old you could ask for a loom replacement but assuming the car will be repaired under warranty it probably depends on what MB UK judge is an adequate repair. Replacing a large section of wiring loom might create more problems than anything else.
Disappointing for you on a virtually new car!

 

[kamatr]

FUse 57 was indicated by the MB Break Down Technician as protecting the Engine Control Unit (!)

 

[grober]

Mmmmmm! Under these circumstances I would document the full history of the incident and the proposed repairs in writing to MB UK for their response. I would include any misgivings you have about the repair and request assurances any faults that may occur in the future due to this incident such as failure/malfunction of the engine ECU will be treated appropriately. It should all be covered by the 3 year warranty but its still maybe a good idea to have something in writing to MB UK about the incident.