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c0225 ABS Code cant figure it out

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by ippielb, Feb 20, 2014.

  1. ippielb

    ippielb Epic Member 5+ Years ROTM Winner 1000 Posts

    2002 Chevrolet Silverado 1500 4x4 with tow package, had the abs light come up, it is a C0225, EFI Live says open rear abs sensor. I cannot for the life of me figure this code out. I have just went through the entire truck replaced everything, flushed the engine, transmission and rear differential, new air and fuel filter, new bulbs, i went and got a new ABS sensor for the front because that's what i thought it was, but now it's not. Hopefully parts shop will let me return it, as it was $75 and i dont need it.

    Anyone know how to fix this C0225 ABS code?
  2. Pikey

    Pikey Moderator Staff Member 2 Years ROTM Winner 1000 Posts

    if efi live said open rear abs sensor why did you change the front? or was that a typo?
  3. Scott_Anderson

    Scott_Anderson Member 2 Years 100 Posts

    Not sure about yours, but on my old 2000 K2500 OBS, I had a similar ABS code for 'faulty front left speed sensor'.
    I tested the sensor, replaced the sensor, swapped the wiring between the left/right sensor, and nothing I did allowed the fault to go away. I relegated the fault to a failed ABS controller and disconnected all the electrical to the ABS module so as not have the ABS light on the dash.
    In essence I disabled the ABS and just drove with regular pre-ABS brakes.
  4. ippielb

    ippielb Epic Member 5+ Years ROTM Winner 1000 Posts

    Checked it before i bought the sensor, had about 6 abs codes come up, C0226, C0221, C0225, ect., then a bunch of U1000, U1016, U1041, U1096, U1064, and a B0026... So i had a lot to work with, i ended up unplugging the battery went to the city, bought a new starter(why i got no start codes), new ABS sensor, bunch of filters blah blah blah, came back home, changed starter, hooked battery back up, checked codes again, now i only get 1, which is the C0225. And it doesn't tell me which sensor it is.
    If i was keeping the truck then i might do that, but i cannot afford to have the truck waste away sitting, so it's time to sell it. When i sell something, i always put the shoe on the other foot. How would i want it. Kind of a karma thing.
  5. Pikey

    Pikey Moderator Staff Member 2 Years ROTM Winner 1000 Posts

    I found this, I don't know much about it, but maybe it will help.

    DTC C0221-C0227
    Circuit Description
    As the wheel spins, the wheel speed sensor produces an AC signal. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed.

    Conditions for Running the DTC
    C0221 and C0225
    The ignition is ON.

    C0222, C0223, C0226 and C0227
    The vehicle speed is greater than 32 km/h (20 mph) when the brake is applied or 19 km/h (12 mph) when the brake is released.

    Conditions for Setting the DTC
    C0221 and C0225
    The EBCM detects an open or shorted wheel speed sensor or wheel speed sensor circuit for 500 milliseconds.

    C0222 and C0226
    The corresponding wheel speed sensor signal is less than 6 km/h (4 mph) for 5 seconds, or 120 seconds in order to set both DTCs.

    C0223 and C0227
    The EBCM detects an erratic signal from the corresponding wheel speed sensor for 105 milliseconds.

    Action Taken When the DTC Sets
    C0221, C0225
    If equipped, the following actions occur:

    The EBCM disables the ABS/TCS.
    The ABS indicator turns ON.
    The TRACTION OFF indicator turns ON.
    C0222, C0223, C0226, and C0227
    If equipped, the following actions occur:

    The EBCM disables the ABS/TCS and may disable DRP.
    The ABS indicator turns ON.
    The TRACTION OFF indicator turns ON.
    The red Brake warning indicator may turn ON.
    Conditions for Clearing the DTC
    Repair the condition responsible for setting the DTC.
    Use a scan tool in order to clear the DTC.
    After the DTC is cleared and the ignition is ON, the ABS indicator may remain ON until the EBCM completes a power-up self-test. This test concludes when the vehicle reaches a speed greater than 13 km/h (8 mph) and the wheel speeds are verified by the EBCM.
    Diagnostic Aids
    Operating the vehicle on extremely rough terrain can set DTC C0223, C0227 or C0229 even if the system is functioning normally.

    Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Intermittent and Poor Connections , Connector Repairs , Testing for Electrical Intermittents and to Wiring Repairs in Wiring Systems.

    If the customer's concern is that the ABS indicator is on only during humid conditions such as rain, snow or vehicle wash, thoroughly inspect the wheel speed sensor circuits for signs of water intrusion. Use the following procedure in order to help isolate the problem area:

    Spray the suspected area with a 5 percent salt water solution.
    Drive the vehicle at a speed greater than 19 km/h (12 mph) for at least 30 seconds.
    Repair or replace the suspect harness if the DTC sets.

    Test Description
    The numbers below refer to the step numbers on the diagnostic table.

    Measure the resistance of the wheel speed sensor in order to determine if the sensor has a valid resistance value.

    Ensures that the wheel speed sensor is generating a valid AC voltage output.
  6. ippielb

    ippielb Epic Member 5+ Years ROTM Winner 1000 Posts

    That's good to know, thank you, i didn't know that it had to exceed 8mph. I thought it only had to get any kind of reading. I guess i have to take the truck out of the shop for a little drive.
  7. j cat

    j cat Rockstar 3 Years 1000 Posts

    the rear wheel sensor voltage is too high.. remove clean connector , then if necessary replace the rear sensor.
  8. silverado002

    silverado002 Member

    Wheel sensor should read between 700 and 2000 ohms.
  9. RayVoy

    RayVoy Active Member 2 Years 1000 Posts

    I don't know if the 2002 uses 4 channel (sensor at each wheel), or 3 channel ABS (2 fronts and rear drive-shaft).

    If you can't find wheel sensors at the rear, look for it in the transmission to t-case connection (that part of the transfer case at the rear of the transmission, where the tail piece would be on a 2WD truck).
  10. silverado002

    silverado002 Member

    Looking at the ABS schematic it shows wheel sensors for the front but nothing for the rear. Like RayVoy says, I believe it may be using the vehicle speed sensor in the trans too.

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