| Diagnosis and Testing Refer to Wiring Diagrams Cell 42, for schematic and connector information. Special Tool(s) | | Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool | | | 73III Automotive Meter 105-R0057 or equivalent | | | Flex Probe Kit 105-R025B | Principles of Operation The anti-lock brake system (ABS) module manages anti-lock braking. When the ignition switch is placed in the RUN position, the ABS module carries out a preliminary electrical check. At approximately 20 km/h (12 mph), the hydraulic pump motor is turned on for approximately 0.5 second. Any malfunction of the ABS disables the ABS and the yellow ABS warning indicator illuminates; however, the power-assist braking system still functions normally. The ABS module receives wheel speed readings from each wheel speed sensor and processes this information to determine if an ABS event is necessary. The wheel speed sensor electrically senses each tooth of the wheel speed sensor indicators as they pass through the wheel speed sensor magnetic field. The active wheel speed sensor generates a signal that is sent to the ABS module. The wheel speed sensor circuitry connects to the ABS module through 2 wires and a connector at each wheel speed sensor. When the ignition is turned to the RUN position, the ABS module carries out a self-test by sending a reference voltage to all of the wheel speed sensors through their circuitry to determine if they are functional. The ABS module continuously monitors and compares the rotational speed of each wheel and when it detects an impending wheel lock, modulates brake pressure to the appropriate brake caliper. This is accomplished by triggering the hydraulic control unit (HCU) to open and close the appropriate solenoid valves. Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves to their normal positions, and normal (base) braking resumes. The HCU has additional internal solenoid valves incorporated to enable control modulation of the wheel brake pressures. The ABS module is self-monitoring. When the ignition switch is turned to the RUN position, the ABS module will do a preliminary electrical check, and at above 20 km/h (12 mph) the pump motor is turned ON for approximately 1/2 second. Also, during all phases of operation the ABS module, with the vehicle in motion, checks for correct operation of the wheel speed sensors. Any malfunction of the ABS will cause the ABS to shut off. Normal power assisted braking, however, remains. ABS Module Configuration The ABS module needs to be configured whenever a new ABS module is installed. Follow the scan tool directions for the configuration procedure. Electronic Brake Force Distribution The electronic brake force distribution controls the rear brake pressure and acts as an electronic proportioning valve. It is controlled by the ABS module. When the electronic brake force distribution is disabled, the yellow ABS warning indicator illuminates. Panic Assist Braking Using a specially developed pressure/pedal movement mechanism, the panic assist braking functions by fully applying the brakes during a panic stop. Depending on the vehicle speed, if a pedal stroke is more rapid than normal, the brake booster automatically applies full brake boost. Panic assist is disabled when the driver releases the brake pedal. Inspection and Verification NOTE:If a new ABS module is installed, it must be configured. Follow the scan tool directions. - Verify the customer concern.
- Verify the stoplamps operate correctly by applying and releasing the brake pedal with the ignition switch in the OFF position. If the stoplamps do not operate correctly, refer to Section 417-01 Exterior Lighting. If the stoplamps operate correctly, proceed to the next step.
- Verify that the PRNDL operates correctly on the instrument cluster. If the PRNDL does not operate correctly, refer to Section 413-01 Instrument Cluster. If the PRNDL operates correctly, proceed to the next step.
- Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart | Mechanical | Electrical | - Wheel speed sensor ring
- Hydraulic control unit (HCU)
- Base brake system
- Brake booster vacuum hose
- Steering components and suspension components
- Tire size
| - Battery junction box (BJB) fuse(s):
- Smart junction box (SJB) fuse(s):
- Anti-lock brake system (ABS) module
- Wheel speed sensor
- Stoplamp switch
- Brake pressure transducer
- Brake fluid level switch
- Circuitry
| - If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
-
NOTE:Make sure to use the latest scan tool software release. If the cause is not visually evident, connect the scan tool to the data link connector (DLC). -
NOTE:The vehicle communication module (VCM) LED prove out confirms power and ground from the DLC are provided to the VCM. If the scan tool does not communicate with the VCM: - check the VCM connection to the vehicle.
- check the scan tool connection to the VCM.
- If the scan tool does not communicate with the vehicle:
- verify the ignition key is in the ON position.
- verify the scan tool operation with a known good vehicle.
- Carry out the network test.
- If the network test passes, retrieve and record continuous memory diagnostic trouble codes (DTCs).
- Clear the continuous DTCs and carry out the self-test diagnostics for the ABS module.
- If the DTCs retrieved are related to the concern, go to Anti-Lock Brake System (ABS) Module Diagnostic Trouble Code (DTC) Index. For all other DTCs, refer to Section 419-10 Multifunction Electronic Modules.
- If no DTCs related to the concern are retrieved, GO to Symptom Chart.
Anti-Lock Brake System (ABS) Module Diagnostic Trouble Code (DTC) Index Symptom Chart Symptom Chart | Symptom | Possible Sources | Action | | No communication with the anti-lock brake system (ABS) module | * Circuitry * ABS module | * | | The red brake warning indicator stays on when the ignition switch is in the RUN position | * Circuitry * Parking brake * Brake fluid level sensor * Instrument cluster * Anti-lock brake system (ABS) module | * | | The yellow anti-lock brake system (ABS) warning indicator does not self-check | * Circuitry * Instrument cluster * ABS module | * | | Spongy brake pedal with no warning indicator | * Air in brake hydraulic system * Base brakes | * | Pinpoint Tests Pinpoint Test A: DTC B1676 — Battery Pack Voltage Out of Range Refer to Wiring Diagrams Cell 42, for schematic and connector information. Normal Operation The vehicle electrical system supplies power between 12 and 14 volts to the anti-lock brake system (ABS) module. Voltage is supplied by circuit 483 (RD) to the ABS module. Ground for the ABS module is provided through circuit 570 (BK/WH). Possible Causes - Circuit open
- Charging system
- ABS module
| PINPOINT TEST A : DTC B1676 — BATTERY PACK VOLTAGE OUT OF RANGE | CAUTION:Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | A1: CHECK THE BATTERY VOLTAGE | | | 1 Measure the battery voltage between the positive and negative battery posts with the key ON engine OFF (KOEO), and then with the engine running. | | | Is the battery voltage between 10 and 13 volts with KOEO, and between 11 and 17 volts with the engine running? Yes No | | A2: CHECK CIRCUIT 483 (RD) FOR AN OPEN | | | 1 Ignition switch in position 0. | | | 2 For vehicles equipped with a 3.0L engine, with the vehicle in NEUTRAL, position it on a hoist. Refer to Section 100-02 Jacking and Lifting. | | | 3 Disconnect ABS Module C155. | | | 4 Ignition switch in position II. | | | 5 Measure the voltage between ABS module C155-32, circuit 483 (RD), harness side and ground. | | | Is the voltage greater than 10 volts? Yes No REPAIR circuit 483 (RD). CLEAR the DTCs. REPEAT the self-test. | | A3: CHECK CIRCUIT 570 (BK/WH) FOR AN OPEN | | | 1 Ignition switch in position 0. | | | 2 Measure the resistance between ABS module C155-16, circuit 570 (BK/WH), harness side and ground. | | | Is the resistance less than 5 ohms? Yes No REPAIR circuit 570 (BK/WH). CLEAR the DTCs. REPEAT the self-test. | | A4: CHECK FOR CORRECT ABS MODULE OPERATION | | | 1 Disconnect the ABS connector. | | | 2 Check for: | | | 3 Connect the ABS connector and make sure it is seated correctly. | | | 4 Operate the system and verify the concern is still present. | | | Is the concern still present? Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. | Pinpoint Test B: DTC C1095 — ABS Hydraulic Pump Motor Circuit Failure Refer to Wiring Diagrams Cell 42, for schematic and connector information. Normal Operation The operating voltage required to run the hydraulic pump motor is between 10 and 17 volts. Voltage for the hydraulic pump motor is supplied to the anti-lock brake system (ABS) module through circuit 534 (YE/LG). Ground for the hydraulic pump motor is provided through circuit 570 (BK/WH) and the ABS module. Possible Causes - Circuit open
- Hydraulic pump motor
- ABS module
| PINPOINT TEST B : DTC C1095 — ABS HYDRAULIC PUMP MOTOR CIRCUIT FAILURE | CAUTION:Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | B1: CHECK THE ABS PUMP MOTOR | | | 1 Ignition switch in position II. | | | Is the ABS pump motor running all the time? Yes No | | B2: CHECK THE PUMP MOTOR OPERATION | | | 1 Ignition switch in position 0. | | | 2 Connect the diagnostic tool. | | | 3 Ignition switch in position II. | | | 4 Enter the following diagnostic mode: ABS Module Active Command. | | | 5 Trigger the ABS module pump motor ON active command. | | | Does the ABS pump motor run for approximately 3 seconds? Yes CLEAR the DTCs. CHECK the yellow ABS warning indicator while driving the vehicle (brakes must not be applied) at greater than 32 km/h (20 mph). If the yellow ABS warning indicator illuminates, RETRIEVE the DTCs. If DTC C1095 is retrieved, GO to B5. . No TRIGGER the ABS module pump motor OFF active command. GO to B3. . | | B3: CHECK CIRCUIT 534 (YE/LG) FOR AN OPEN | | | 1 For vehicles equipped with a 3.0L engine, with the vehicle in NEUTRAL, position it on a hoist. Refer to Section 100-02 Jacking and Lifting. | | | 2 Ignition switch in position 0. | | | 3 Disconnect ABS Module C155. | | | 4 Ignition switch in position II. | | | 5 Measure the voltage between ABS module C155-1, circuit 534 (YE/LG), harness side and ground. | | | Is the voltage greater than 10 volts? Yes No REPAIR circuit 534 (YE/LG). CLEAR the DTCs. REPEAT the self-test. | | B4: CHECK CIRCUIT 570 (BK/WH) FOR AN OPEN | | | 1 Ignition switch in position 0. | | | 2 Measure the resistance between ABS module C155-47, circuit 570 (BK/WH), harness side and ground. | | | Is the resistance less than 5 ohms? Yes No REPAIR circuit 570 (BK/WH). CLEAR the DTCs. REPEAT the self-test. | | B5: CHECK FOR CORRECT ABS MODULE OPERATION | | | 1 For vehicles equipped with a 3.0L engine, with the vehicle in NEUTRAL, position it on a hoist. Refer to Section 100-02 Jacking and Lifting. | | | 2 Disconnect the ABS connector. | | | 3 Check for: | | | 4 Connect the ABS connector and make sure it is seated correctly. | | | 5 Operate the system and verify the concern is still present. | | | Is the concern still present? Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. | Pinpoint Test C: DTCs C1145, C1155, C1165 and C1175 — Wheel Speed Sensor Input Circuit Failure Normal Operation The active wheel speed sensor generates a square wave signal that is sent to the anti-lock brake system (ABS) module. The wheel speed sensor circuitry connects to the ABS module connector C155 through 2 wires and a connector at each wheel speed sensor. When the ignition is turned to the RUN position, the ABS module carries out a self-test by sending a reference voltage through the wheel speed sensors and their circuitry to determine if they are functional. Power and ground are supplied to the active wheel speed sensors from the ABS module. Possible Causes - Circuit open
- Circuit shorted
- Wheel speed sensor
- ABS module
| PINPOINT TEST C : DTCS C1145, C1155, C1165 AND C1175 — WHEEL SPEED SENSOR INPUT CIRCUIT FAILURE | CAUTION:Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | C1: CHECK THE WHEEL SPEED SENSOR CIRCUITS FOR A SHORT TO POWER | CAUTION:No measurements should be taken with the wheel speed sensor connected. Damage to the wheel speed sensor will result. | NOTE:Both circuits must be checked for each DTC. | | | 1 Ignition switch in position 0. | | | 2 For vehicles equipped with a 3.0L engine, with the vehicle in NEUTRAL, position it on a hoist. Refer to Section 100-02 Jacking and Lifting. | | | 3 Disconnect ABS Module C155. | | | 4 Disconnect Suspect Wheel Speed Sensor. | | | 5 Ignition switch in position II. | | | 6 For DTC C1145, measure the voltage between ground and: - ABS module C155-33, circuit 516 (YE/BK), harness side.
- ABS module C155-34, circuit 514 (YE/RD), harness side.
| | | 7 For DTC C1155, measure the voltage between ground and: - BS module C155-45, circuit 521 (TN/OG), harness side.
- BS module C155-46, circuit 522 (TN/BK), harness side.
| | | 8 For DTC C1165, measure the voltage between ground and: - ABS module C155-42, circuit 524 (PK/BK), harness side.
- ABS module C155-43, circuit 523 (RD/PK), harness side.
| | | 9 For DTC C1175, measure the voltage between ground and: - ABS module C155-36, circuit 518 (LG/RD), harness side.
- ABS module C155-37, circuit 519 (LG/BK), harness side.
| | | Is voltage present? Yes REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test. No | | C2: CHECK THE WHEEL SPEED SENSOR CIRCUITS FOR A SHORT TO GROUND | NOTE:Both circuits must be checked for each DTC. | | | 1 Ignition switch in position 0. | | | 2 For DTC C1145, measure the resistance between ground and: - ABS module C155-33, circuit 516 (YE/BK), harness side.
- ABS module C155-34, circuit 514 (YE/RD), harness side.
| | | 3 For DTC C1155, measure the resistance between ground and: - ABS module C155-45, circuit 521 (TN/OG), harness side.
- ABS module C155-46, circuit 522 (TN/BK), harness side.
| | | 4 For DTC C1165, measure the resistance between ground and: - ABS module C155-42, circuit 524 (PK/BK), harness side.
- ABS module C155-43, circuit 523 (RD/PK), harness side.
| | | 5 For DTC C1175, measure the resistance between ground and: - ABS module C155-36, circuit 518 (LG/RD), harness side.
- ABS module C155-37, circuit 519 (LG/BK), harness side.
| | | Are the resistances greater than 10,000 ohms? Yes No REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test. | | C3: CHECK THE WHEEL SPEED SENSOR CIRCUITS FOR AN OPEN | NOTE:Both circuits must be checked for each DTC. | | | 1 Disconnect Suspect Wheel Speed Sensor. | | | 2 For DTC C1145, measure the resistance between: - ABS module C155-33, circuit 516 (YE/BK), harness side and RH front wheel speed sensor C160-1, circuit 516 (YE/BK), harness side.
- ABS module C155-34, circuit 514 (YE/RD), harness side and RH front wheel speed sensor C160-2, circuit 514 (YE/RD), harness side.
| | | 3 For DTC C1155, measure the resistance between: - ABS module C155-45, circuit 521 (TN/OG), harness side and LH front wheel speed sensor C150-2, circuit 521 (TN/OG), harness side.
- ABS module C155-46, circuit 522 (TN/BK), harness side and LH front wheel speed sensor C150-1, circuit 522 (TN/BK), harness side.
| | | 4 For DTC C1165, measure the resistance between: - ABS module C155-42, circuit 524 (PK/BK), harness side and RH rear wheel speed sensor C426-2, circuit 524 (PK/BK), harness side.
- ABS module C155-43, circuit 523 (RD/PK), harness side and RH rear wheel speed sensor C426-1, circuit 523 (RD/PK), harness side.
| | | 5 For DTC C1175, measure the resistance between: - ABS module C155-36, circuit 518 (LG/RD), harness side and LH rear wheel speed sensor C440-1, circuit 518 (LG/RD), harness side.
- ABS module C155-37, circuit 519 (LG/BK), harness side and LH rear wheel speed sensor C440-2, circuit 519 (LG/BK), harness side.
| | | Are the resistances less than 5 ohms? Yes No REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test. | | C4: CHECK FOR SHORTED WHEEL SPEED SENSOR CIRCUITS | | | 1 Measure the resistance between the suspect wheel speed sensor pins, harness side. | | | Is the resistance greater than 10,000 ohms? Yes No REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test. | | C5: CHECK THE ABS MODULE OUTPUT | | | 1 Connect ABS Module C155. | | | 2 Ignition switch in position II. | | | 3 Measure the voltage between the suspect wheel speed sensor pins, harness side. | | | Is the voltage less than 9 volts? Yes No | | C6: CHECK FOR CORRECT ABS MODULE OPERATION | | | 1 Disconnect the ABS connector. | | | 2 Check for: | | | 3 Connect the ABS connector and make sure it is seated correctly. | | | 4 Operate the system and verify the concern is still present. | | | Is the concern still present? Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. | Pinpoint Test D: DTCs C1233, C1234, C1235 and C1236 — Wheel Speed Sensor Input Signal Missing Refer to Wiring Diagrams Cell 42, for schematic and connector information. Normal Operation The wheel speed sensor and sensor ring generate a square wave signal to the anti-lock brake system (ABS) module that is proportional to the wheel speed. The ABS module compares the wheel speed inputs from all of the wheel speed sensors to determine an impending wheel lockup. Possible Causes - Wheel speed sensor
- Wheel speed sensor ring
- Wheel bearing
- ABS module
| PINPOINT TEST D : DTCS C1233, C1234, C1235 AND C1236 — WHEEL SPEED SENSOR INPUT SIGNAL MISSING | CAUTION:Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes. | | TEST CONDITIONS | DETAILS/RESULTS/ACTIONS | | D1: CHECK THE DTCS FROM THE SELF-TEST | | | 1 Using the recorded results from the ABS self-test: | | | Are DTCs C1145, C1155, C1165 or C1175 present? Yes No | | D2: MONITOR THE WHEEL SPEED PIDS | | | 1 Connect the diagnostic tool. | | | 2 Ignition switch in position II. | | | 3 Enter the following diagnostic mode: ABS Module PIDs. | | | 4 Use the scan tool to monitor the ABS module wheel speed sensor PIDs while driving the vehicle at a constant speed. | | | Are all the wheel speed sensor PID values similar? Yes CLEAR the DTCs. DRIVE the vehicle. RETRIEVE the DTCs. If DTCs C1233, C1234, C1235 or C1236 are present, GO to D9. . No | | D3: INSPECT THE WHEEL SPEED SENSOR MOUNTING | | | 1 Ignition switch in position 0. | | | 2 | | | 3 Inspect the wheel speed sensor mounting. | | | Is the wheel speed sensor loose? Yes TIGHTEN the wheel speed sensor to specification. CLEAR the DTCs. GO to D4. . No | | D4: RECHECK THE WHEEL SPEED PIDS | | | 1 Connect the diagnostic tool. | | | 2 Ignition switch in position II. | | | 3 Enter the following diagnostic mode: ABS Module PIDs. | | | 4 Use the scan tool to monitor the ABS module wheel speed sensor PIDs while driving the vehicle at a constant speed. | | | Are all the wheel speed sensor PID values similar? Yes The vehicle is OK. The concern may have been caused by a loose wheel speed sensor. No | | D5: CHECK THE WHEEL SPEED SENSOR FOR DAMAGE | | | 1 Ignition switch in position 0. | | | CAUTION:Examine the wheel speed sensor wire carefully with a good light source. Failure to verify damage in the wheel speed sensor wire can lead to unnecessary installation of a new component. 2 Inspect the wheel speed sensor for damage. | | | Is the wheel speed sensor OK? Yes No | | D6: CHECK FOR WHEEL SPEED SENSOR RING DAMAGE | | | 1 | | | 2 Inspect the wheel speed sensor ring for damaged or missing teeth. Rotate the wheel to verify that no teeth are missing. | | | Is the wheel speed sensor ring OK? Yes No | | D7: CHECK FOR BEARING DAMAGE | | | 1 Inspect the wheel bearings for damage. | | | Are the wheel bearings OK? Yes No | | D8: CHECK THE ABS MODULE OUTPUT | | | 1 Ignition switch in position 0. | | | 2 Disconnect Suspect Wheel Speed Sensor. | | | 3 Ignition switch in position II. | | | 4 Measure the voltage between the suspect wheel speed sensor pins, harness side. | | | Is the voltage greater than 10 volts? Yes No | | D9: CHECK FOR CORRECT ABS MODULE OPERATION | | | 1 Disconnect all the ABS connectors. | | | 2 Check for: | | | 3 Connect all the ABS connectors and make sure they seat correctly. | | | 4 Operate the system and verify the concern is still present. | | | Is the concern still present? Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. | |
