We recently bought a Yeti and didn't realise that the rear wiper wasn't working, I tracked the lack of activity down to a missing fuse in the interior fuse box, but when I replaced it I found that the rear wiper ran all the time (one wipe every 10 seconds) no matter where the wiper stalk was set, also would randomly trigger and sometimes run continuous while driving. I also found an error code in the BCM which rather unhelpfully said "Pump electronics failure" and no other information.

The rear motor has power all the time via the now replaced fuse, on pins 1 and 4. Pins 2-3 connect to the BCM and the washer motor, which triggers the rear wiper to do 3 wipes after washing, or runs continuous if you hold the stalk on wash. 

I found pin 2 of the motor shorted to ground, after pulling the whole tailgate apart as well as the D-pillar plastics to get acccess to the wiring loom. This wire causes the motor to run once every 10 seconds when it's connected to ground. 

After pulling the dashboard apart to check the BCM I found the short circuit was not inside the BCM, but when I removed the plug from the washer pump the short circuit became intermittent. If I pulled and pushed on the harness the short would come and go.  

I traced the short circuit down to the wiring loom underneath the drivers side (RHS/RHD) headlight unit, this car has Xenon headlights and I found a badly placed wiring loom was shorting on the metal casing of the ballast. 

Headlight top, wiring loom middle, inner wing below. 

 

Headlight removed, zero ohms between washer pump connector and probe touching bared surface of wire. 

 

Hole in Green wire, barely visible. 

 

Area under the headlight where the wire was touching. 


Managed to separate the wires out of the loom, cleaned and insulated the notch with some impact glue, wrapped with self amalgamating tape, electrical tape and eventually relocated the loom and protected with Teflon Spiral-wrap. 

Full functionality was restored after turning the ignition off and on again, please note that if the BCM detects a short circuit it WILL NOT try again until you cycle the ignition. 

Note that you can reach the washer pump clip through the slit in the front bumper and by removing the trim panel directly below the washer bottle, in front of the front wheel. The manual says to remove the bumper but it's not strictly necessary. 

Well done fella. I had a feeling you might find something like this. Loom shorts to chassis seem to be getting accidentally/carelessly 'designed in' more and more often, sadly.