1996 GMC K1500 ABS wiring????

Discussion in 'GMC Truck Forum' started by fair66, Feb 14, 2010.

  1. fair66

    fair66 New Member

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    My 1996 GMC K1500 has the ABS light on , My brakes work fine and are ok, I had two mechanics try to read the code with snapon ABS readers, both got same results ..Can Not comunicate.. I have checked fuses and plugs to the unit. They said probable the control board but wanted to charge me a lot of money to try the board in just to see if would fix. Any ideas on what this could be and where could I find a detailed wiring diagram of the ABS wiring to and from the control board so I can check the wiring . The Chilton manual is pretty vague and don't show much on ABS. Any help would be greatly apreciated..Thanks
     
  2. semocoachworks

    semocoachworks Senior Member

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    Crabtruck is the local diagram library. Let him give it a shot.
     
  3. fair66

    fair66 New Member

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    Thanks I am new to forum maybe he will see this or I will find him and send a message .. I was wrong it was a HAYNES manual i tried not Chilton. My motor is a 5.7 Vortec.
     
  4. semocoachworks

    semocoachworks Senior Member

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    Someone else may chime in and have the diagram but I'm sure crab can help you. Welcome to the forum by the way. Lots of knowledge and good people here.
     
  5. davbell22602

    davbell22602 Senior Member

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    welcome to the forum

    [​IMG]


    Pump Motor Circuit


    1. Check the condition of the fuse in the relay center and replace as necessary.
    2. Unplug the pump motor electrical connection.
    3. Check the condition of the terminals and the wiring harness terminals. Repair as necessary.
    4. Attach the electrical connection.
    5. Using a Digital Volt OhmMeter (DVOM) set to read voltage, backprobe between the black (ground) wire and red (power) wire terminals of the harness . The voltage should be between 9-14 volts.
    6. If the voltage is less than 9 volts, set the DVOM on the lowest resistance scale, disconnect the harness and the positive and negative battery terminals. Connect one probe to the positive battery cable and the other probe to red wire terminal. Note the reading. Connect one probe to the negative battery cable and the other probe to black wire terminal. Note the reading.
    7. If the resistance is less than one ohm the wiring is fine and the control unit should be replaced.
    8. If the resistance is more than one ohm, clean and tighten the terminals or repair the wiring as needed.
    9. Attach all unplugged wires and recheck the voltage.
    10. Clear the trouble codes and road test the vehicle. If the trouble code returns, check the motor supply voltage again.
    11. If the voltage is now between 9-14 volts and the pump is still not functioning properly, replace the assembly.
    12. If the voltage is still lower than 9 volts, there may be a problem with the EBCM.

    Wheel Speed Sensor


    1. Elevate and safely support the vehicle.
    2. Unplug the sensor electrical connection.
    3. Check the condition of the sensor terminals and the wiring harness terminals. Repair as necessary.
    4. Check the sensor wiring harness for an open or short circuit. Repair as necessary.
    5. Using a Digital Volt OhmMeter (DVOM) set to read resistance, probe the sensor terminals.
    6. If the resistance is not as specified in the accompanying charts, the sensor may be defective.
    7. Turn the DVOM to the A/C voltage scale and spin the wheel, there should be a voltage reading. As the wheel speed increases, the voltage should increase. If there is no voltage present, or the voltage does not increase with wheel speed, check the tone wheel for defects. If the tone wheel is found to be in good condition, replace the sensor.

    View attachment 91029g01.pdf
     
  6. crabtruck

    crabtruck Senior Member

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    Welcome to the firum fair66.

    Not sure I really understand the diagnostic effort.
    Were the mechs able to connect a reader at all to the truck ?
    Were they saying that they only could NOT communicate w/ ABS ?
    The first is not an ABS related problem.

    You should be aware that there was a problem with 96 GMC's
    setting false codes for ABS of 35,36,and 37 all due to
    driver turning key from run to off too slowly, or
    having a slight movement of truck at time of keying off.
    A fix would involve replacing ECM sice this was most common
    in manual trans, or VCM if in an auto trans.
    Believe you could just clear codes and ignore
    if there are no other brake symptoms.

    Since you don't have a code to work with, the first thing
    I think you should be asking is about any ABS brake symptoms.
    As in can you tell if they ever engage/work as ABS.
    Common cause for ABS code with out obvious problems
    was dirty sensors in front wheels. I think they would be a good place
    to start troubleshooting, as well as looking for clean tight connections
    at the BPV (the ABS box) since so easy to check.

    Not sure what models dave's steps are for but idea is good one.

    I only have this one wire draw at this time, maybe it'll help.

    Good hunting.

    (Kind words semocoachworks)
    .
    [​IMG]
     

    Attached Files:

  7. michbo62

    michbo62 Full Member

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    I had the same problem with my 95 Yukon (ABS light came on).
    I thought it was a problem with the hub sensor. The problem, which one? Here is what I did to find it.
    I used an analog multimeter (the kind with a needle) set it to ohms x 1000
    I disconnected the sensor and probed the two pins, while I turned the hub slowly I watched the needle, and it moved just a little bit! This told me the hub I was checking was good.
    I then checked the other front wheel bearing, and sure enough nobody home! It was dead!
    I bought a new hub bearing, and replaced the bad one. And it worked! The ABS light went out! :woot::woot:

    Hope this helps
     

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