Polarity swap normal? and what part is broken

Discussion in 'Ask An Owner Operator' started by skallagrime, Sep 7, 2021.

  1. skallagrime

    skallagrime Road Train Member

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    Kw t600 94

    Okay, got a headscratcher here for yall

    When i turn key on, dash warning lights come on like they should, then after a few seconds, engine light goes away, everything else remains.

    This is annoying but fine i guess, pull fuse and add a seperate low air light warning, is what it is.

    what i DO have an issue with may be linked to the cluster stopping proper operation. the signal wires from 5th wheel, air dump etc at key cycle flip polarity depending on if the fuse to warning panel is on or not

    So no fuse/key off power, key on if i hit the air dump signal wire (to cluster) it is negative, when i ADD the fuse, it becomes positive.

    Im guessing this is because the warning cluster wants to turn on the light to make sure it works, then shut itself off after 3 seconds so by simply polarity switching for those few seconds, it can, but its "stuck"? So they never turn off.

    Well, heres my problem with that, i changed to 12v solenoids triggered by relays from switches, so cycling a key would dump air, release 5th wheel lock diff for 3 seconds, and that didnt seem great.

    So question 1, why do it that way? Seems weird to go to swapping polarity for a light
    Question 2, what probably broke resulting in warning cluster constantly stuck?

    How would you set up the wiring if you did fix it so i could have air dump warning light cycle but not have the air actually dump?
     
  2. Ridgeline

    Ridgeline Road Train Member

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    94?
    Did you check the grounds at the cluster?
     
    skallagrime Thanks this.
  3. skallagrime

    skallagrime Road Train Member

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    And yes, 1994

    Yes and no, at cluster its constantly being powered, no matter what i do if key is on. It is entirely possible that this is linked to my dash lights turning on with key, spent 6 hrs tracing things last night, but fixed 4 problems and this one is persistent, almost like the dash lights have a nick SOMEWHERE to hot, turning em on all the time.

    Left my fancy electric tester at home so only have led red/green test lead atm and can rig up a spare voltmeter i dont trust much at each spot

    Already disconnected dimmer switch from the mix but that didnt do anything