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CVD's avatar
CVD
Explorer
Dec 20, 2017

Blowing Fuse When In Reverse

I have one fuse for turn signals and back up lights, which is blowing when I put it in reverse (takes 2 – 3 seconds, I then hear a faint pop). I’ve started looking at the wires coming out of the shifter box, trying to figure which carries the reverse signal (which would be where I’d look for something causing a short).

However, thinking more about it, aren’t the reverse and neutral sensors (NSS) physically on the transmission? If so, my problem isn’t in the wires coming from the shifter (by the dash), but on the transmission (or somewhere between the transmission and back up lights)?

Either way, any suggestions on tracking down this problem? Coach is on 98 Freightliner chassis, ISB engine, MT643 trans.

Thanks,
Class A

13 Replies

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  • TNGW1500SE's avatar
    TNGW1500SE
    Explorer
    Dec 21, 2017
    Take the bulbs out and see if it still blows. If not install a new bulb in one side. See if it blows. If not replace other side bulb with new bulb. May be that simple.
  • ScottG's avatar
    ScottG
    Nomad
    Dec 21, 2017
    The trans switch usually just connects the wire to ground, completing the path for the negative side. A failed switch usually means either no b/u lights or they're always on.
    So it's probably not the switch.

    Has someone connected bigger, brighter b/u lights? If so they could be too much for the circuit.
  • MrWizard's avatar
    MrWizard
    Moderator
    Dec 21, 2017
    why do you think its a switch

    i would open the backup/reverse lights and check the lamps and wiring at the lights

    (2-3) minutes in reverse, sounds like a light full if water to me

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