Xtreme V light not working.

Discussion in 'Fisher Engineering Discussion' started by john r, Dec 3, 2019.

  1. john r

    john r Senior Member
    from NJ
    Messages: 288

    The drivers side light doesn't work. Low beam is very dim and the high beam doesnt turn on. I swapped bulbs, cleaned harness pins, looked for chaffed harness. I want to check the voltage at the connector. The 2 rows of pins are labeled 1 (top) and 7 (bottom). I can't find the diagram of the pin lay out.
     
  2. Philbilly2

    Philbilly2 PlowSite Fanatic
    Messages: 11,505

    What type of truck are we working on and is this a new install or has it worked in the past?

    3 port module under the hood?
     
  3. JFon101231

    JFon101231 Senior Member
    from CT
    Messages: 714

  4. OP
    OP
    john r

    john r Senior Member
    from NJ
    Messages: 288

    2008 F350. Plow installed in 08. Lights did work last year. 3 port module under hood.
     
  5. OP
    OP
    john r

    john r Senior Member
    from NJ
    Messages: 288

    I checked the resistance (11 pin harness) from pins 4 and 5 are open and pins 5 and 6 are open (zero resistance). I also applied 12 volts to the pins and the high and low beams did not light up. Looks like the harness is bad. There's no part number label on it. Can I purchase the harness separetly or do I need to buy the lights too to get the harness?
     
  6. JFon101231

    JFon101231 Senior Member
    from CT
    Messages: 714

    Can buy just harness. Do you need it for regular square headlights or intensifires?
     
  7. OP
    OP
    john r

    john r Senior Member
    from NJ
    Messages: 288

    For intensifires.
     
  8. Mebes

    Mebes Senior Member
    Messages: 662

    Drivers side bulb (plowside) resistance should be measured between pins 4 and 11 for high and pins 6 and 11 for low.

    Edit: Assuming 55 watts at 12 volts should be seeing ~2.5 ohm's

    Screenshot_20191205-181220.png
     
    Last edited: Dec 5, 2019
  9. OP
    OP
    john r

    john r Senior Member
    from NJ
    Messages: 288

    I checked pins 4,6, and 11. 2.5 ohms. Harness is good. I'm thinking it is the isolation module because when the plow connector is disconnected plow side the DS headlight does not come on.
     
  10. Mebes

    Mebes Senior Member
    Messages: 662

    Headlamp does not work truck side?
    Could be module but may also be connections at the headlamp itself.

    I'd unplug b harness from module and check input before throwing parts at it.

    Unplug plow - unplug b harness from module - turn headlamps on - probe VA to VJ (BJ) for 12 volts on low beam - probe VB to VJ (BJ) for high.

    Screenshot_20191206-100532.png

    Mechanics guide if you dont have it already is here http://library.fisherplows.com/publications.asp?cat=35
     
    JFon101231 likes this.
  11. OP
    OP
    john r

    john r Senior Member
    from NJ
    Messages: 288

    OK I could not read any output form the Isolation module from the B plug. I decided to try the C plug output for the passenger side in comparison. Same thing, no output. Fisher was smart to label each wire for function. This leaves no doubt what wires your looking for. I'm thinking the IM needs the connector installed to complete the head light "out" circuit. The module I'm working on is 29760-1
     
  12. Mebes

    Mebes Senior Member
    Messages: 662

    Oops sorry I may not have been clear...
    You are looking for input to the module on the B harness so when you unplug it probe the wires not the module for incoming power.

    This test will tell you if you have a bad connection to the factory harness behind the drivers headlamp.

    If you want to test output of the module, B will need to be plugged in and you will need to back probe the harness on D to K and E to K for low.
     
  13. unhcp

    unhcp PlowSite.com Addict
    Messages: 1,316

    usually the port a cable goes bad, 99% of the time

    26357# part number
     
    gtmustang00 likes this.