Well looking at the wiring for that truck it appears that out of the 5 fuses they show on it, only one of them actually powers the wipers. That is fuse 39 located at the Integrated Power Module under the hood behind the battery. The others power things like the body module, the stalk and the washer fluid level light that is actually powered through the dash.
So, I would test fuse 39. Beyond that you need a dealer level Consault scan tool to test the IPDM itself, it has a built-in diagnostic that the scan tool can read and display errors. That is because other than the washer motor all of the rest is controlled in the IPDM, the relays are soldered to the board inside it and if it's a bad relay you replace the complete module.
About the only testing you can do without a scan tool would be to use a test light at the wiper motor plug. Turn on the key, turn the wipers on low, Connect the light to a good ground and hold it onto pin 3. Then switch to high and test pin 2. If the relays are working you should see the light come on when those are selected. Now if you have a light on either or both, disconnect the light from the ground and clamp a pin or needle in the claw, then put that on pin one and check power on high again. If the light comes on the ground is good. At that point I would suspect the motor itself.
The test light is also handy to test the fuses. 39 for instance should have power full time, even with the key off.
https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester
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Monday, July 21st, 2025 AT 12:30 PM
