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Complaint - Customer was in a yard that was slick, put the truck into 4WD and 4WD error lights appeared on dash. Truck never went into 4WD.
DTCs - P180F Motor System, P186A Front Axle Function, P186B Front Axle Control, P1867 Incomplete Shift
I found right away that the ground wire at what's called something like the front axle disengagement actuator was broken right at the connector. I fixed that wire and still no good. I only have the P186A now though, if that means anything. I found no power at that connector. Found that the relay that provides power to it is grounded by the transfer case control unit. When I disconnect that module and provide the ground, I get power at the connector. Good powers and grounds at that module. Only other issue is that I get no activity from that actuator when it has power and ground applied to it.
The question is, do I have two bad parts, or could the bad actuator disable that relay from being grounded by some current sensing ability? It's a warranty repair, so they typically don't like paying for more than one part, unless I can really prove that two are faulty.
I am going to check the actuator for an internal short that may have hurt the driver, but I'm not sure about this.
How many wires are on the actuator? If it's two wires see if you can move actuator in both directions by flipping polarity with harness disconnected. If it goes one way and not the other then actuator motor is bad. If it's multiple wires then see which supplies power for each direction and manually do it like above. If it works then wiring from module or module is bad.
It has four wires, two for the solenoid and two are inputs from the module that have to do with switch position I believe. When I tried that last night I got nothing, so I ordered the actuator. I'm just not sure if the module is shot too, but the parts just got here so I'm about to find out!
So bench testing the old one again, nothing. New one, nothing. Those inputs must be required but I don't know what's going on in the thing to know how it works. This brings me back to the module...
I dangled the new actuator under the truck, plugged in, and it works. Fully installed it for the fix. I think next time I would leave everything connected and just ground the relay at the TC CU pin and see if the actuator moves when I go in 4wd.
Must be. Bench testing might be done with power and ground, and a 5v adapter from my power probe on one of the inner wires. 0v on one and 5v on the other, depending on 2wd or 4wd. I wonder if that would have worked.
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