My partner's 62-plate Fabia Monte Carlo has a clear short circuit with the rear wiper. How do I know this? Well, after only a few days left undriven the battery gets drained. Removing the fuse (No. 26) means that this doesn't happen. Jump starting the battery is fine, and the alternator is recharging as expected.

 

What I'm wondering is, is there anything I can do about sorting this without resorting to a auto-electrician?

Does the rear wiper actually work?

It is not a short circuit. That would take the fuse out. Something is causing a drain. There is a lot more in the circuit than just the rear wiper.

2 hours ago, sepulchrave said:

Does the rear wiper actually work?

Yep. Functions normally as expected.

 

2 hours ago, Jocko said:

It is not a short circuit. That would take the fuse out. Something is causing a drain. There is a lot more in the circuit than just the rear wiper.

The fuse is not blowing when in place. Removing the fuse clealry prevents the drain on the battery compared to when the fuse is in place.

6 hours ago, El Hair said:

has a clear short circuit with the rear wiper.

It's not a conventional short, since that would either blow the fuse or leave the wiper running non stop. It's probably a CANBus error on that circuit (and no I don't know how to trace those).

Thanks for this. Much appreciated.

Could be the wiper motor is not "switching off" properly or has an internal fault causing the drain.

 

I would unplug the wiper motor itself and see if the problem is the same regarding the battery drain, this would prove or not if the wiring to the rear hatch is "ok" and would isolate to where the problem is likely to be........

 

have you put an ammeter on the battery to read any parasitic drain ?  Out of interest what lead you to the rear wiper fuse ?

 

Standard vehicle starter batteries don't like being flattened completely and often damage is done when they are, maybe more relevant to an older battery, so the battery "may" not be able to now hold a charge, because it jump starts and the alternator is providing a charging voltage does not comfirm all is ok.

 

 

Edited 25 March, 20233 yr by UrbanPanzer