S124 rear wiper blowing fuse No 1

crt

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Your Mercedes
'95 E300D estate, '16 Golf, '58 Unimog 404, '95 Defender CSW
1995 E300D estate. Fuse number 1 kept blowing whenever ignition is switched on. After much analysis and exposing of old wiring, fault isolated to rear wiper. It is shorting to earth. One of the problems in tracking the fault was that when the boot lid was fully up, there was no short, but when down, beginning from about half way down, it shorts. This leads me to believe there must be wire damage somewhere around the hinge area where the loom goes through, as is often reported.

The short disappears when the wiper motor is disconnected from the large five pin plug inside the lid. I have unbolted the motor so that the metal body is electrically isolated from the metal of the lid, yet when plugged in it will still short when the lid is more than part way down. What I don’t understand is why this should be happening The wiring diagram shows an unswitched live from the fuse directly to the wiper and relay, but if this was shorting around the hinge area it would happen even if the motor was unplugged.

Does anyone know if some part of the circuitry creates an always on live circuit from the wiper motor when it is plugged in but not otherwise?

Thanks.
 


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