Thread: Rear wiper no power

If you have a D3 then it's Relay R273 (Connector C2397) in the passenger rear compartment near the trailer fuses. It also supplies power to the Ignition power outlet on the white trailer socket. Engine bay fuse 16 is a main supply to the CJB. The other side of the relay is driven straight from the CJB.

If you don't have a D3 then this is all irrelevant.

Edit : Checked the D4 diagram. The location is correct but it looks like a double relay (wiper and power are separate contacts & coils). On the D4 F16 is the direct supply to the rear wiper relay in the rear passenger compartment. So same same but different. Connector highlighted on D4 diagram below.
Screenshot_2024-01-04_13-40-08.jpg

Our Subaru Outback has broken, for the second time, the wire to the rear wiper.
It breaks were it bends every time you open the tailgate.

That said, I would have thought a D4 would be clever enough to tell it was open circuit.

Tony

Legend - thanks BradC! I did not know there was another fuse box there. Mine is a D4 so thanks for checking. I'll go take a look tomorrow.

TonyC that sounds like a questionable design choice. The D4 has many of those

Originally Posted by Disco4TT3

I did not know there was another fuse box there. Mine is a D4

I don't believe there is a fuse box there on the D4, but the connector diagram still locates the relays in that location on the D4 for both the wiper and trailer ignition pin. Given it's location on the drawing, you might be looking right down the back corner at or below floor level. Just follow the harness.

Last time I went away I lost my caravan camera feed. Turns out stuff I stashed in the compartment gave the harness a tug and it became disconnected. Anything is possible.

I found my multimeter , did some testing and I'm getting power to the assembly. So Im assuming the relays, fuses and wiring harness are all good.

Since the next easy but expensive step is replacing the wiper assembly, I decided to pull it apart and see what's what:

IMG_0075.jpg IMG_0076.jpg

Removed the motor:

IMG_0077.jpg

and although there seems to be some wear on the inside:

IMG_0079.jpg

When I connected to a 12v battery, the motor worked fine.

I checked the brass connectors behind the main cog and found some grease covering one of the connectors. But sadly, wiping it off didn't help.

With the wipers 'on', I can see 12v coming from the harness to the assembly but only 0.3v coming from the assembly to the motor:

IMG_0081.jpg

So digging deeper, I see this little sucker:

IMG_0082.jpg

The connections are all good, so suspecting this component might be the issue. Stretching my non-existent electronics skills here, but think that might be a capacitor? Anyone know?

I've resigned myself to replacing the assembly, but keen to try and repair for the hell of it!

Originally Posted by Disco4TT3

Stretching my non-existent electronics skills here, but think that might be a capacitor? Anyone know?

Yep, and you're spot on. That cap will be for arc suppression on the motor. If it was open, the motor would still work and if it was shorted it'd go off like a fire cracker when you put 12V on it, so I'm suspecting the fault lies elsewhere.

Given your first indicator of the fault was a blown fuse, I suspect "something bad" happened to cause the fault, because fuses don't get old, tired and blow for no reason.

Diagnostics have been great thus far, keep on probing.

So it's fixed - but unfortunately I'm not sure what fixed it!?

I cleaned the contacts behind the main cog again but with an alcohol swab this time, reassembled and the motor ran. But don't think this could've caused the initial short which made the fuse blow.

One gotcha I found while reassembling, make sure you mark the position of the cog and the internal ratcheted metal arm before you remove. When I first put the external wiper arm back on, it went backwards!

I rotated the cog 180 and it still didn't work, then reattached the ratcheted arm to the opposite hole in the cog and that worked. I don't have a pic but anyone rebuilding will see what I mean.

Happy days. I saved a few hundred bucks (for now).

Thanks for your help BradC!