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Home >> Ford >> 2021 >> Explorer Limited Hybrid, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 497 (Abs Guided Routine) >> Pinpoint Tests >> Pinpoint Tests M: Front Wheel Speed Sensor Electrical Faults >> Visual Inspection and Diagnostic Pre-checks

Visual Inspection and Diagnostic Pre-checks

WARNING: This page is about a different car, the 2020 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.
Fig 1: Anti-Lock Brake System-A (ABS-A) Module Connector - C135A
G13402631Courtesy of FORD MOTOR CO.

Harness Side

Circuit Pin
LF WSS LO (Left Front Wheel Speed Sensor Low) - RCA17 7 (YELLOW)
LF WSS HI (Left Front Wheel Speed Sensor High) - VCA03 6 (VIOLET/WHITE)
RF WSS LO (Right Front Wheel Speed Sensor Low) - RCA19 11 (GREEN/WHITE)
RF WSS HI (Right Front Wheel Speed Sensor HI) - VCA05 10 (GRAY/VIOLET)
Fig 2: Anti-Lock Brake System-B (ABS-B) Module Connector - C135B
G13402632Courtesy of FORD MOTOR CO.

Harness Side

Circuit Pin
Fig 3: Left Front Wheel Speed Sensor Connector - C150
G13402633Courtesy of FORD MOTOR CO.

Harness Side

Circuit Pin
LF WSS LO (Left Front Wheel Speed Sensor Low) - RCA17 2 (YELLOW)
LF WSS HI (Left Front Wheel Speed Sensor High) - VCA03 1 (VIOLET/WHITE)
Fig 4: Right Front Wheel Speed Sensor Connector - C160
G13402634Courtesy of FORD MOTOR CO.

Harness Side

Circuit Pin
RF WSS LO (Right Front Wheel Speed Sensor Low) - RCA19 2 (VIOLET)
RF WSS HI (Right Front Wheel Speed Sensor HI) - VCA05 1 (GRAY/VIOLET)
  1. M1: CHECK FOR FAULT REPEATABILITY 
    • Ignition ON, engine OFF.
    • Clear the ABS DTCs.
    • Put the ABS module in sleep mode by performing the following steps:
      • With ALL doors closed, set the ignition from ON to OFF.
      • Disconnect the diagnostic scan tool.
      • Open the door, exit the vehicle and close the door.
      • Wait a minimum of 90 seconds for the ABS module to enter sleep mode.
    • Ignition ON, engine OFF.

      Carry out the ABS self-test.

    • Are any of the DTCs shown in the DTC Fault Trigger Conditions table present? 
      Yes No
      If ONLY DTC C1A90:12, C1A90:16 or C1A95:01 is present, Go to  M2.
      For failure type byte 11 (Circuit Short to Ground) or 14 (Circuit Short to Ground or Open Circuit), Go to  M4.
      For failure type byte 01 (General Electrical Failure), 12 (Circuit Short to Ground) or 15 (Circuit Short to Battery or Open Circuit), Go to  M3.      		 The system is operating correctly at this time. INSPECT both front wheel speed sensor electrical connectors and the ABS module electrical connector. REPAIR or CLEAN the connector as necessary. ADDRESS the root cause of any connector or pin issues.
  2. M2: DETERMINE WHICH WHEEL SPEED SENSOR IS AT FAULT 
    • Test drive the vehicle while recording the wheel speed sensor PIDs.
    • Access the ABS and monitor the LF_WSPD (SPD) PID.
    • Access the ABS and monitor the RF_WSPD (SPD) PID.
    • Access the ABS and monitor the LR_WSPD (SPD) PID.
    • Access the ABS and monitor the RR_WSPD (SPD) PID.
    • Is a front wheel speed sensor at fault? 
      Yes No
      Go to  M3. GO to PINPOINT TEST N .
  3. M3: CHECK THE WHEEL SPEED SENSOR CIRCUITS FOR A SHORT TO BATTERY VOLTAGE 
    NOTE: The battery must be removed to access the ABS module electrical connector.
    • Ignition OFF.
    • Remove the battery. Refer to the appropriate procedure in the Battery, Mounting and Cables article.
    • ABS_A Module connector disconnected. (C135A)
    • ABS_B Module connector disconnected. (C135B)
    • Install the battery. Refer to the appropriate procedure in the Battery, Mounting and Cables article.
    • Disconnect the suspect wheel speed sensor.
    • Ignition ON, engine OFF.
    • For the left front wheel speed sensor:
    • Measure the voltage between:
      (+) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side (-)
      LF WSS LO - RCA17 (YELLOW) - Pin 2 Ground
      LF WSS HI - VCA03 (VIOLET/WHITE) - Pin 1 Ground
    • For the right front wheel speed sensor:
    • Measure the voltage between:
      (+) Right Front Wheel Speed Sensor (C160) Connector, Harness Side (-)
      RF WSS LO - RCA19 (VIOLET) - Pin 2 Ground
      RF WSS HI - VCA05 (GRAY/VIOLET) - Pin 1 Ground
    • Is any voltage present? 
      Yes No
      REPAIR the circuit. Go to  M4.
  4. M4: CHECK THE WHEEL SPEED SENSOR CIRCUITS FOR A SHORT TO GROUND 
    • Ignition OFF.
    • ABS_A Module connector disconnected. (C135A) If not previously disconnected.
    • ABS_B Module connector disconnected. (C135B) If not previously disconnected.
    • Disconnect the suspect wheel speed sensor (if not previously disconnected).
    • For the left front wheel speed sensor:
    • Measure the resistance between:
      (+) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side (-)
      LF WSS LO - RCA17 (YELLOW) - Pin 2 Ground
      LF WSS HI - VCA03 (VIOLET/WHITE) - Pin 1 Ground
    • For the right front wheel speed sensor:
    • Measure the resistance between:
      (+) Right Front Wheel Speed Sensor (C160) Connector, Harness Side (-)
      RF WSS LO - RCA19 (VIOLET) - Pin 2 Ground
      RF WSS HI - VCA05 (GRAY/VIOLET) - Pin 1 Ground
    • Are the resistances greater than 100, 000 ohms? 
      Yes No
      Go to  M5. REPAIR the circuit.
  5. M5: CHECK FOR SHORTED WHEEL SPEED SENSOR CIRCUITS 
    • For the left front wheel speed sensor:
    • Measure the resistance between:
      (+) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side (-) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side
      LF WSS HI - VCA03 (VIOLET/WHITE) - Pin 1 LF WSS LO - RCA17 - Pin 2
    • For the right front wheel speed sensor:
    • Measure the resistance between:
      (+) Right Front Wheel Speed Sensor (C160) Connector, Harness Side (-) Right Front Wheel Speed Sensor (C160) Connector, Harness Side
      RF WSS HI - VCA05 (GRAY/VIOLET) - Pin 1 RF WSS LO - RCA19 - Pin 2
    • Are the resistances greater than 100, 000 ohms? 
      Yes No
      Go to  M6. REPAIR the circuit.
  6. M6: CHECK THE WHEEL SPEED CIRCUITS FOR AN OPEN 
    • For the left front wheel speed sensor:
    • Measure the resistance between:
      (+) ABS Module Connector, Harness Side (-) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side
      LF WSS LO LF WSS LO - RCA17 - Pin 2
      LF WSS HI LF WSS HI - VCA03 - Pin 1
    • Measure the resistance between:
      (+) ABS_A Module (C135A) Connector, Harness Side (-) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side
      LF WSS LO - RCA17 (YELLOW) - Pin 7 LF WSS LO - RCA17 - Pin 2
      LF WSS HI - VCA03 (VIOLET/WHITE) - Pin 6 LF WSS HI - VCA03 - Pin 1
    • For the right front wheel speed sensor:
    • Measure the resistance between:
      (+) ABS Module Connector, Harness Side (-) Right Front Wheel Speed Sensor (C160) Connector, Harness Side
      RF WSS LO RF WSS LO - RCA19 - Pin 2
      RF WSS HI RF WSS HI - VCA05 - Pin 1
    • Measure the resistance between:
      (+) ABS_A Module (C135A) Connector, Harness Side (-) Right Front Wheel Speed Sensor (C160) Connector, Harness Side
      RF WSS LO - RCA19 (GREEN/WHITE) - Pin 11 RF WSS LO - RCA19 - Pin 2
      RF WSS HI - VCA05 (GRAY/VIOLET) - Pin 10 RF WSS HI - VCA05 - Pin 1
    • Are the resistances less than 3 ohms? 
      Yes No
      Go to  M7. REPAIR the circuit.
  7. M7: CHECK THE ABS MODULE OUTPUT 
    • ABS_A Module connector connected. (C135A) Make sure the connector seats and latches correctly.
    • ABS_B Module connector disconnected. (C135B)
    • Ignition ON, engine OFF.
    • For the left front wheel speed sensor:
    • Measure the voltage between:
      (+) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side (-) Left Front Wheel Speed Sensor Sensor (C150) Connector, Harness Side
      LF WSS HI - VCA03 (VIOLET/WHITE) - Pin 1 LF WSS LO - RCA17 - Pin 2
    • For the right front wheel speed sensor:
    • Measure the voltage between:
      (+) Right Front Wheel Speed Sensor (C160) Connector, Harness Side (-) Right Front Wheel Speed Sensor (C160) Connector, Harness Side
      RF WSS HI - VCA05 (GRAY/VIOLET) - Pin 1 RF WSS LO - RCA19 - Pin 2
    • Is the voltage greater 11 volts? 
      Yes No
      INSTALL a new WSS.
      REFER to the Anti-Lock Brake System (ABS) and Stability Control article.      		 Go to  M8.
  8. M8: VERIFY ALL WIRING CONNECTIONS 
    • Ignition OFF.
    • ABS_A Module connector disconnected. (C135A) (if not previously disconnected)
    • ABS_B Module connector disconnected. (C135B) (if not previously disconnected)
    • Using a good light source, inspect all disconnected electrical connectors for the following:
      • corrosion - install new connector or terminal and clean the module pins
      • damaged or bent pins - install new terminals or pins
      • pushed-out pins - install new pins as necessary
      • spread terminals - install new terminals as necessary
    • Are the connectors free of corrosion, damaged pins, bent pins, pushed-out pins and spread terminals? 
      Yes No
      Go to  M9. REPAIR the affected connectors or terminals. Refer to the Connector Repair Procedures wiring diagrams for schematic and connector information.
  9. M9: CHECK FOR APPLICABLE SERVICE ARTICLES 
    • Check OASIS for any service articles: TSB, GSB, SSM or FSA.
    • Do any applicable service articles exist? 
  10. M10: CHECK FOR CORRECT ABS MODULE OPERATION 
    • ABS Module connector connected. Make sure the connector seats and latches correctly.
    • Connect the suspect wheel speed sensor electrical connector. Make sure the connector seats and latches correctly.
    • Operate the system and determine if the concern is still present.
    • Is the concern still present? 
      Yes No
      INSTALL a new ABS module.
      INSTALL a new ABS module. REFER to the Anti-Lock Brake System (ABS) and Stability Control article.
      ORDER a replacement ABS module and INCLUDE the RVC on the form.
      If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form.      		 The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.
  11. M11: CHECK FOR CORRECT ABS OPERATION 
    • ABS_A Module connector connected. (C135A) Make sure the connector seats and latches correctly.
    • ABS_B Module connector connected. (C135B) Make sure the connector seats and latches correctly.
    • Connect the suspect wheel speed sensor electrical connector. Make sure the connector seats and latches correctly.
    • Operate the system and determine if the concern is still present.
    • Is the concern still present? 
      Yes No
      INSTALL a new EBB assembly.
      The HCU and ABS module are a single assembly known as the EBB unit.
      INSTALL a new EBB unit (HCU and ABS module assembly). REFER to the Anti-Lock Brake System (ABS) and Stability Control article.
      ORDER a replacement EBB unit and INCLUDE the RVC on the form.
      If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form.      		 The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.
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