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Test 2: Wheel Speed Sensor Signal Problem

  1. Inspect wheel speed sensor air gap. See WHEEL SPEED SENSOR AIR GAP  under ADJUSTMENTS. Adjust as necessary. Ensure sensor(s) are not damaged. If sensor adjustment is as specified and no damage exists, go to next step.
  2. Raise and support vehicle. Ensure all connectors are connected. Turn ignition on. Backprobe ABS/TCS control unit connector with oscilloscope test probes while rotating each wheel depending on trouble code. See WHEEL SENSOR INPUT VOLTAGE table. Voltage should be .12-1.00 volt (AC waveform). If input voltage is not as specified or waveform is erratic, go to next step. If input voltage is as specified, replace ABS/TCS control unit.
    CHECKING WHEEL SENSOR INPUT VOLTAGE

    DTC Terminals No.
    22 (1) 8 & 16
    24 (2) 1 & 11
    26 (2) 2 & 12
    28 (1) 7 & 15
    (1) Terminals are located in ABS/TCS control unit 16-pin harness connector. Second terminal listed is to be connected to oscilloscope ground lead.
    (2) Terminals are located in ABS/TCS control unit 20-pin harness connector. Second terminal listed is to be connected to oscilloscope ground lead.
  3. Turn ignition off. Disconnect ABS/TCS control unit connectors. Measure resistance between ground and terminal No. 6 at ABS/TCS control unit 6-pin harness connector. See Figure . Measure resistance between ground and terminal No. 5 at ABS/TCS control unit 8-pin harness connector. Measure resistance between ground and terminal No. 15 at ABS/TCS control unit 20-pin harness connector. If all resistance readings are less than one ohm, go to next step. If any resistance reading is more than one ohm, repair wiring harness as necessary.
  4. Turn ignition off. Depending on specific trouble code, disconnect appropriate ABS wheel sensor connector. Measure resistance between wheel sensor terminals. If resistance is 800-1200 ohms, go to next step. If resistance is not 800-1200 ohms, replace wheel sensor.
  5. Check wheel sensor wiring harness connectors for damaged, loose or corroded terminals. Repair as necessary. If connectors are okay, check mobile phone, personal radio and other wireless equipment for proper installation (if equipped). Ensure antenna and other possible noise sources are not touching or close to wheel sensor wiring harness. Ensure sealed wiring in front wheel sensor wiring harness (in engine compartment) is grounded securely. Ensure that wiring harness between ABS/TCS control unit and rear wheel sensor has a twist pitch of .98" (25 mm) or less. Repair as necessary. If no problems are found, go to next step.
  6. Check hydraulic unit operation. See COMPONENT TESTING  . If hydraulic unit is okay, replace ABS/TCS control unit.
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