Let me preface this with the statement that my brake lights all work correctly, the brake switch works correctly and activates both relays in both the depressed and further depressed position. Both relays have been tested and function correctly.

A couple nights ago I was going to run to the store and get some food. It had been raining for a while and then froze.

I noticed when I got into the truck, I went to hit my wipers to clear the windshield and they would not stop wiping. I turned the truck off completely, then turned it back on. No problem, I turned the headlights on and the wipers started up again. Weird... then the big problem, I couldn't get out of park. I started poking around and checking combinations of problems to determine the electrical problem that I am having.

With the ignition on II, if I hit the brake the parking interlock pin retracts allowing me to operate the gear selector. Unfortunately if I hit the brakes momentarily while the vehicle is in park, the windshield wipers wipe several times and stop. If I hold the brake down the wipers wipe constantly.

With the ignition on II, the vehicle in drive, everything works correctly until I turn the headlights on. The front and rear windshield wipers wipe. They act as if the washer pump has been activated, although I do not hear the pump. They are not wiping on intermittent, it is a constant several swipes then it stops.

With the ignition on II, while the wipers are wiping, hitting the brakes does not apply enough voltage to the park interlock circuit to fully retract the pin. It does get voltage and moves a little, but not enough to fully move the pin. Sometimes hitting the rear window washer button will provide enough power to pull the pin back. Waiting until the wipers have stopped wiping will provide enough power.

With the ignition on II, hitting the headlight washer button will click the park interlock relay and allow the pin to be fully retracted momentarily.

With the ignition on II, head lamps off but fog lamp button depressed, pressing the rear window washer button will cause the fog lamps to illuminate.

Running the MFU diagnostic test comes back fine, with the exception that the fog lamps illuminate approximately the same time the front wipers wipe.

At this point I suspect a bad MFU and currently have one ordered, but it will not be here for a week or so.

Is there anything else I can test to make sure? I'm going to go through all the wiring and WD40/Dielectric grease everything to make sure that there is no water trapped in the harnesses.

Thanks.