Why does my rear wiper fuse keep blowing?

[John Brennand]

Last Summer the rear wiper on my MY2006 stopped working. Checked fuse first and replaced No.19 15A one n the cargo fuse box. All OK for a couple of days and then went again. Bought a new pack of fuses and a new 3d party motor from eBay. Worked fine until just before Christmas then the same sequence happened. I thought I may have bought a pup, so just got a genuine Volvo used one, from a scrappy on the Bay. That worked fine until today. Just replaced fuse 19 and its ok .... but until when !

I dont believe in coincidence and that 3 motors in succession have a fault.... so anyone seen similar and what fixed it?

Or got any thoughts on what might be causing it, where to look first? Would a VIDA code read be informative in that regard, or is it the time for an auto-electrician to take a look?

Thanks for any ideas. John

[Moose Test]

I'm in the process of attempting to troubleshoot what sounds like a very similar, if not identical scenario.

Prior to December, I noticed that my rear wiper had started to not operate at times. This became progressively worse and I ended up purchasing an aftermarket motor from eBay and fitting that. Up to this point, I'd not yet had a fuse blow. Although I had recorded, during initial troubleshooting, that whilst there was mostly 12v present on the motor connector when turned on, on one occasion that was not the case, even though the fuse remained intact.

After less than a week of being operational, my new motor has started blowing fuses too. Like you, I suspected a 'pup'. But given the initial symptoms, and now reading your experiences, I'm beginning to wonder.

I'm starting to consider that either there may be a problem within the REM, or that the tailgate wiring loom has been physically damaged in a way that leads to either occasional breaks or shorts.

[paddy74]

Originally Posted by Moose Test

[...]
I'm starting to consider that either there may be a problem within the REM, or that the tailgate wiring loom has been physically damaged in a way that leads to either occasional breaks or shorts.

That would be my first try. I didn't had it on the XC90, but on nearly every old Volvo I've ever owned (despite the 944, but all station wagons).

Fortunately they normally break right in the middle of the accessable loom.

Take a look here:
https://www.volvoforums.org.uk/showthread.php?t=260136
and linked in that thread is another one:
https://www.volvoforums.org.uk/showthread.php?t=260136

Have fun with it, or go with a new loom from Volvo, IIRC it was around EUR 150. It's helpful, if you have a height adjustable chair.

[John Brennand]

Originally Posted by paddy74

That would be my first try. I didn't had it on the XC90, but on nearly every old Volvo I've ever owned (despite the 944, but all station wagons).

Agree - my old 245 went to its grave because of it and only a total rewire by a helpful member on here saved my XC70.

I have ju t kinda assumed that they had sorted the issues on the XC9o - or are they still common.

Will VIDA be informative?

[Moose Test]

Originally Posted by John Brennand

Will VIDA be informative?

No. At least, not in my case. I've had cause within the timeframe of this failure to clear logged DTCs due to an unrelated issue (Engine Service Required message, caused by low/failing battery) and there was nothing logged for the REM or CEM.

On the plus side, I did take a quick look at the state of my loom at the cable entry points (top of the tailgate) and I see nothing concerning, at least, nothing readily visible or as outright catastrophic as the damage shown in the thread paddy74 linked.

[John Brennand]

Originally Posted by Moose Test

No. At least, not in my case. I've had cause within the timeframe of this failure to clear logged DTCs due to an unrelated issue (Engine Service Required message, caused by low/failing battery) and there was nothing logged for the REM or CEM.

On the plus side, I did take a quick look at the state of my loom at the cable entry points (top of the tailgate) and I see nothing concerning, at least, nothing readily visible or as outright catastrophic as the damage shown in the thread paddy74 linked.

Cheers if you get a chance can you post a photo of where to look for the cable entry points for the wires to the wiper motor. Cheers John

[Moose Test]

John

On the XC90, there are two rubberised cable entry conduits at the very top edge of the tailgate, towards the centre of the roof and inboard from the hinges.

The tailgate wiring loom passes through the conduit on the RHS of the vehicle (which is the LHS as viewing from the rear). The other conduit holds the rear washer feed tube and the parking camera cable.

[SwissXC90]

We have a saying in the electronics repair world: anything that moves, can and will break

You have 2 x moving parts: the wiper motor and the cable loom in the hinge area.

The wiper motor you have replaced. The wiper motor will only blow a fuse with a short circuit or an overload, to check for overload inspect how easy the motor moves the wiper arm (on a wet window of course). If you hear it struggling or straining, suspect a gummed up or rusted motor gearbox or wiper arm causing overload. If your wiper motor came complete with gearbox, then the gearbox will be OK.

Next suspect is multiple wire breaks in the loom inside the rubber conduit where the wires flex all the time. Peel back the rubber grommet and inspect. You’ll likely have to remove the tailgate inner cladding and maybe the rear roof liner.
If you see damage and want to do a DIY repair, note the following:

Rarely does one wire break. Most of the time multiple wires break.

Do not make solder joins inside the flex part. Add new wires of appropriate size, and join the wires inside the tailgate and inside the car, so that the flexing part is a continuous, unbroken, wire.

It may be easier for you to fit a new loom - but inspect first, and check prices second, before you commit.

Be wary of 2nd hand looms, you have no idea how many flex cycles they have been through... they may be weeks away from breaking themselves.

[John Brennand]

Thanks Moose and Swiss - very helpful. I will take a look when and if it ever stops pouring down and report back :-)

[Tannaton]

I would start by pulling the connector off the motor, but still switch on the wiper on the stalk control a few times every time you drive it. If the fuse still blows, you have a wiring or REM issue.