2007 Freightliner Traler abs not light up win key is on

Discussion in 'Freightliner Forum' started by FrankieFish, May 29, 2016.

  1. FrankieFish

    FrankieFish Bobtail Member

    5
    0
    May 29, 2016
    0
    I have a 2007 Freightliner Coronado when I turn the key on, my trailer abs light does not come on on the dash when I checked the 7way pin on the back of the cab there is no power to the center wire(blue wire) when checked center pin(blue wire) I find that that position has become grounded but I have checked all abs fuses and breaks in fuse panel plus side panel beside the seat. They all check fine. Anyone have any ideas on what this could be?
     
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  3. BrentP

    BrentP Bobtail Member

    9
    3
    Aug 28, 2014
    Lafayette
    0
    Your trailer ABS lamp should be wired directly to your tractor ABS ECU. You have a PLC filter that determines what goes to the trailer. You can test this filter to see it it isn't sending power to the trailer ABS ECU and will need a DMM....

    Disconnect the 2-wire connector (green/yellow wires) and the 2-wire connector (blue wires) from the filter. The PLC filter is located near the trailer receptacle on the frame rail or crossmember. Follow the single blue wire from the PLC filter to the primary or supplemental receptacle.

    At the 2-pin connector with the green and yellow wires, use a DMM to measure the resistance across the green and yellow wires.
    • If the reading is less than 0.5 ohms, go to the next step.
    • If the reading is more than 0.5 ohms, the tractor ABS power circuit is open in the PLC filter. Replace the filter.

    Determine the receptacle (primary or supplemental) that supplies power to the trailer ABS. Using a DMM, connect one lead to pin 7 of the receptacle that supplies power to the trailer ABS and the other lead to the 2-pin connector on the PLC filter that has the two blue wires. Measure the resistance at both pins on the 2-pin connector.
    • If the reading is less than 1.0 ohm, go to the next step.
    • If the reading is more than 1.0 ohm, there is an open circuit either between the 7-way trailer receptacle and the PLC filter, or in the PLC filter itself. Repair the harness or replace the PLC filter as necessary.

    At the PLC filter, connect one lead of the DMM to the green wire (at the 2-pin connector with the green and yellow wires) and the other lead to one of the blue wires (at the 2-pin connector with the two blue wires). Measure the capacitance.
    • If the reading is 4.8 to 7.2 µF, go to the next step.
    • If the reading is less than 4.8 or more than 7.2 µF, one or more of the internal capacitors is faulty. This may affect PLC functionality and/or noise in the electrical system. Replace the PLC filter.

    At the PLC filter, connect one lead of the DMM to one of the blue wires (at the 2-pin connector that has the two blue wires) and connect the other lead to the ground where the white wire terminates. Measure the capacitance.
    • If the reading is 9.91 to 11.91 µF, the PLC filter is functioning properly.
    • If the reading is less than 9.91 or more than 11.91 µF, check and clean the ground connection where the white wire terminates and retest. If the reading is still unsatisfactory, one or more of the internal capacitors is faulty. This may affect PLC functionality and/or noise in the electrical system. Replace the PLC filter.
     
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