W900 wipers only work on highest setting

Could be the switch or the motor itself.

 

Yep, you have to troubleshoot with a multimeter to determine which one. It could even be an issue with the wiring harness or relay. Wiper motors have a dedicated ground. You can troubleshoot forward or backwards.

I would start with the motor. Unplug the harness from it. Turn the switch on high you will have 12V on one wire. Then turn the switch on low you'll have 12V on a different wire. Yes there is 12V on low at the motor harness then it's the motor. No 12v on low it's most likely the relay or switch. Then go to the relay and do the same thing. Pin 85 comes from the switch. Yes pin 85 is hot then it's the relay. No pin 85 is not hot then it's the switch.

 

Several kenworths with the same problem here. Should be a recall on the switch because 3 of 9 of ours have this problem

 

Did your wiper wash fluid work when only had high setting?

 

There is a recall on the wiper motor, there is a problem of water getting into the motor so they install a shield on it. If there is a fault with the operation of the motor it will be replaced. This covers a wide range of years, believe from 2010 on up.

As for relays, there are 2, one for wiper on/off and one for intermittent operation (timer). if the timer is not working or wipers park at any location, try replacing the intermittent relay first.
From 2010 and up the chassis node controls the washer pump, check the fuses in the chassis load center (fuse block) at the washer bottle location.

 

Is G 7/8 the intermittent relay?



I have an issue with wipers not returning to park. Low and high work fine but it stops anywhere I turn the switch off, no matter what speed I had it on. Intermittent wil go up and stop all the way up and then eventually it will come back down and stop, then it will go back up and stop. It repeats this until it's turned off.


Edit: can't return to park if the park fuse is bad.

 

If the wipers don't park check the fuse at C9, if the fuse is good then the wiper motor has a contact switch inside that failed, will need a new wiper motor.
The G7 relay is the on/off .