(another) Service 4wd

Discussion in 'Engine & Drivetrain' started by SnowDrifter, Jul 8, 2019.

  1. Fless

    Fless Supporting Member

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    Hopefully then it was just a bad connection, and cycling them fixed it.
     
  2. SnowDrifter

    SnowDrifter Full Access Member

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    Problem not solved. Issue persists. Same code

    However, I did get an interesting visual here as I wslas driving at night. The back lights for the selection buttons did not work(though the amber selection indicator did) . But they did after an ignition cycle and the issue resolved.

    Grrrr. Need to dig deeper (fuck)
     
  3. SnowDrifter

    SnowDrifter Full Access Member

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    Ooookay so combining the lack of back light with throwing the code, and knowing the conditions for the code, I'm left with one of a couple options (I think, someone correct me if I'm wrong please help this is a cry for help)

    1. There's an issue with supply voltage to the switch. I don't believe it to be ground related as ground for the switch, based on my understanding of how it's wired, wouldn't affect the output signal which is the condition for setting the code. This bit I'd need some knowledgeable folks who know where the power supply comes from, where the wire runs, and any pinch points

    2. A fault in the power supply feed internal to the switch itself.

    Both of these are difficult to test being that I can't seem to replicate the issue on a consistent basis. So this would be a case of inspecting what I can and seeing if there's anything obvious, or wait until it gets worse and I can replicate the problem to appropriately determine the fix

    Any input /help here would be appreciated. This one's kicking my ass

    SmartSelect_20190713-013208_Drive.jpg SmartSelect_20190713-012910_Firefox.jpg
     
  4. Fless

    Fless Supporting Member

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    I won't be much help on this as I've not done any related troubleshooting and have never had that code, but I'd be inclined to throw a UPull or cheap switch at it (after testing it) to see what happens. From what I've read it's the switch a high percentage of the time. I'm not sure if the Tech 2 will read the ignition voltage, but I do know it will read the 5v from the ATCM under the dash.

    I'm not good at reading wiring diagrams but it looks like the ignition voltage doesn't come from the ATCM. You probably knew that already.

    Might also be a good idea to pull the ATCM out and clean the two connectors. Kind of a pain to get it out from under the dash, though.
     
  5. Fless

    Fless Supporting Member

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    Thought of another thing to try.

    If you think the switch might be the cause, you could disassemble it partway and clean the contacts, and touch up the solder joints on the two connectors. Sorry these pics aren’t the clearest.


    Here’s the switch with the cover removed:

    4x4 Switch 1_resized.jpg


    Pull off the clear light diffuser straight up and set it aside:

    4x4 Switch 2_resized.jpg


    Pull (peel) off the rubber switch contact piece, and clean both those contacts and the corresponding ones on the circuit board with electronic contact cleaner or alcohol. I like to use something that will not only clean the contacts but leave a little film of protection to keep them from oxidizing:

    4x4 Switch 3_resized.jpg


    When you reinstall the rubber piece, make sure the little rubber nibs* seat all the way in the two holes on either side of each contact. The rubber edge should be flat to the circuit board and not lumpy anywhere.


    It would be a good time to re-flow the solder on the contact pins. (If you were to be replacing the backlighting, the correct way to do that is to desolder all those pins, since they’re what hold the PC board to the switch body and contact pins.)


    * I wanted to say “teats” instead of “nibs” but I know how the prudes on this forum would react to that. LOL
     
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