L DTC C1168, C1235 (Dynamic)
NOTE: Refer to the PINPOINT TEST section of the Flow of Diagnosis before beginning this pinpoint test. Flow of DiagnosisNORMAL OPERATION:
The anti-lock brake control module constantly monitors all brake anti-lock sensor signals to ensure that they are proper and do not drop out, have sudden spikes or indicate a situation that is not physically possible.
FAULT DESCRIPTION:
Diagnostic trouble codes (DTC's) are generated by the anti-lock brake control module's detection of a missing, erratic or otherwise improper wheel speed signal from the RR brake anti-lock sensor. The DTCs are set for specific faults at various vehicle speeds. DTC C1168 is generated when the anti-lock brake control module detects that the RR brake anti-lock sensor signal has dropped out or is erratic for a significant period of time. DTC C1168 is only set when the RR brake anti-lock sensor indicates speed greater than 32 km/h (22 mph) with the brake applied or greater than 21 km/h (12 mph) with the brake released. DTC C1235 is generated when the anti-lock brake control module detects that the RR brake anti-lock sensor signal is missing or very low (less than 6.4 km/h [4 mph]) while the other brake anti-lock sensor signals indicate a speed greater than 12.9 km/h (8 mph). At the same time the anti-lock brake control module checks to make sure that drivetrain spin up is not occurring.
NOTE: More than one DTC may be stored for a given failure.
NOTE: DTCs C1168 and C1235 can NOT be set with the vehicle not moving. The vehicle should be driven when attempting to duplicate the concern. If DTCs C1168 and C1235 are set, then the anti-lock brake warning indicator will illuminate and the anti-lock control will be disabled. If the fault is corrected and the signal appears normal, the anti-lock brake warning indicator will be turned "OFF" and the anti-lock control will be enabled. DTCs are stored each time the anti-lock brake warning indicator turns "ON" for any of the above reasons.
POSSIBLE CONTRIBUTING CONDITIONS:
- Damaged right rear brake anti-lock sensor indicator.
- Weak right rear brake anti-lock sensor.
- Incorrect RR brake anti-lock sensor air gap.
- Excessive axle vibration.
- Intermittent short or open in circuit 914 (PK/BL) or circuit 913 (GY/BL).
- Disturbances caused by ignition or Radio Frequency Interference (RFI).
- Defective trigger circuit in the anti-lock brake control module.
L1- Retrieve DTC's
- - Turn ignition switch to "OFF".
- Connect scan tool to Data Link Connector (DLC).
- Turn ignition switch to "RUN".
- Retrieve DTC's using the scan tool.
- Is DTC C1165 retrieved?
YES - Go to Pinpoint test K to Diagnose DTC C1165. Ignore all other DTC's.
NO - If DTC C1165 and/or C1233 is/are retrieved, go to L2.
L2- Repeatability Test Drive (Mismatched Output)
NOTE:
- Recording all speeds for later plotting will eliminate the need of monitoring the scan tool while driving.
- If a hard turn is made, some variation between all four sensors is expected.
- Select all four wheel speed signals from the scan tool PID index.
- Use scan tool to monitor PID's while driving the vehicle at various speeds and over rough roads.
- Does the RR brake anti-lock sensor signal consistently match the others?
YES - Concern is intermittent. Go to L8.
NO - Concern is repeatable. Go to L3.
L3- Check for Internal Sensor Short
- Disconnect RR anti-lock brake sensor.
- Measure Resistance between each sensor pin and ground.
- Does continuity exist?
YES - Replace the RR anti-lock sensor and go to L14.
NO - Go to L4.
L4- Check RR Sensor for Open
- Measure the resistance between the terminals of the RR ABS Sensor connector.
- Is the resistance between 2400 and 2800 ohms?
YES - Go to L5
NO - Replace RR anti-lock sensor and go to L14.
L5- Check Air Gap
- Raise and support the vehicle.
NOTE: The air gap is NOT adjustable. Inspect components for looseness or damage if the air gap is not within specification.
- Measure ABS Sensor Air Gap. The gap should be between 0.76-1.27 mm (0.030-0.050 inch).
- Is the air gap within specification?
YES - Go to L6.
NO - Repair or replace components as necessary and go to L14.
L6- Check Components
NOTE: Examine all components carefully. Failure to properly diagnose component damage at this time will lead to unnecessary component replacement and wasted diagnostic time.
- Remove the RR anti-lock sensor. Rear
- Visually inspect the RR anti-lock sensor indicator, the sensor and sensor cable for signs of damage, corrosion or improper fit.
- Are the components OK?
YES - Reinstall the anti-lock sensor and go to L7.
NO - Replace or repair components as necessary and go to L14.
L7- Check Circuits
- Disconnect the RR anti-lock sensor.
- Disconnect connector C386 from anti-lock control module and connect breakout box and adapter.
- Measure for continuity between breakout box pin 22 and pin 35.
- Measure for continuity between breakout box pin 22 and ground.
- Measure for continuity between breakout box pin 35 and ground.
- Does continuity exist?
YES - Go to L8.
NO - Repair Circuit 913 (GY/BL) and/or 914 (PK/BL) and go to L14.
L8- Begin intermittent Diagnosis
- Disconnect the RR anti-lock sensor.
- Measure the Resistance between the anti-lock sensor terminals (component side).
- Wiggle sensor cable along its entire length.
- Is the resistance measurement erratic during the test?
YES - Replace the anti-lock sensor and go to L14.
NO - Go to L9.
L9- Check for Intermittent RR Anti-Lock Sensor Open
NOTE: If at first the resistance measurement is 2400-2800 ohms, drive the vehicle over rough roads while an assistant monitors the reading for any change. This procedure is recommended to detect intermittent sensor coil failures. Normal brake applications will heat the sensor coil to help bring out intermittent high resistance faults.
- Measure the resistance between the terminals of the RR brake anti-lock sensor connector.
- Is the resistance between 2400 and 2800 ohms?
YES - Go to L10.
NO - Replace the RR anti-lock sensor and go to L14.
L10- Check for Intermittent RR Anti-Lock Sensor Short
NOTE: Use the beeper function on the multimeter to help detect an intermittent short to ground.
- Measure for continuity between each terminal of the RR ABS Sensor and ground.
- Drive the vehicle over rough roads at various speeds while an assistant monitors the resistance.
- Is continuity ever indicated?
YES - Replace the RR anti-lock sensor and go to L14.
NO - Go to L11.
L11- Check for Intermittent Open
- Disconnect connector C386 from anti-lock control module and connect breakout box and adapter.
- Install a jumper wire between the two pins of the RR ABS Sensor connector (harness side).
NOTE: Use the beeper function on the multimeter to help detect an intermittent open.
- Measure the resistance between breakout box pin 22 and pin 35.
- Drive the vehicle over a rough road while an assistant monitors the resistance.
- Is an intermittent open circuit found?
YES - Repair Circuit 913 (GY/BL) and/or 914 (PK/BL) and go to L14.
NO - Remove jumper wire and go to L12.
L12- Check Circuit for an Intermittent Short
NOTE: Use the beeper function on the multimeter to help detect changes in continuity.
- Measure the resistance between breakout box pin 22 and ground.
- Drive the vehicle over a rough road while an assistant monitors the resistance.
- Measure the resistance between breakout box pin 35 and ground.
- Drive the vehicle over a rough road while an assistant monitors the resistance.
- Is an intermittent open circuit found?
YES - If intermittent was detected on Pin 22 repair circuit 914 (PK/BL) and go to L14.
- If intermittent was detected on Pin 35 repair circuit 913 (GY/BL) and go to L14.
NO - Go to L13.
L13- Check Components
NOTE: Examine all components carefully. Failure to properly diagnose component damage at this time will lead to unnecessary component replacement and wasted diagnostic time.
- Remove the RR anti-lock sensor. Rear
- Visually inspect the RR anti-lock sensor indicator, the sensor and sensor cable for signs of damage, corrosion or improper fit.
- Are the components OK?
YES - Replace the anti-lock brake control module and go to L14.
NO - Replace or repair components as necessary and go to L14.
L14- Verify Repair
- Reconnect all disconnected components. Restore vehicle.
- Clear all DTC's using the scan tool.
- Repeat the Drive Cycle Test.
- Retrieve DTC's using the scan tool.
- Is System Pass obtained?
YES - Go to L15.
NO - If original code is retrieved, go to L2 and repeat Pinpoint Test L.
- If a different DTC is retrieved, return to DTC Index.
L15- Verification Test Drive
NOTE:
- Recording all speeds for later plotting will eliminate the need of monitoring the scan tool while driving.
- If a hard turn is made, some variation between all four sensors is expected.
- Select all four wheel speed signals from the scan tool PID index.
- Use scan tool to monitor PID's while driving the vehicle.
- Gradually and smoothly accelerate the vehicle from a stop to 32.2 km/h (22 mph) several times.
- Does the RR brake anti-lock sensor signal consistently match the others?
YES - Stop, Repair is complete.
NO - Concern is repeatable, Go to L3.