H DTC C1155 Front Left Sensor Diagnosis (Electrical/Static)

NOTE: Refer to the PINPOINT TEST section of the Flow of Diagnosis before beginning this pinpoint test. Flow of Diagnosis

NORMAL OPERATION:
With the vehicle at rest, the anti-lock brake control module monitors all brake anti-lock sensors for coil integrity.

FAULT DESCRIPTION:
Diagnostic trouble code (DTC) C1155 is generated by the anti-lock brake control module's detection of an open LF brake anti-lock sensor coil or an open in circuit 912 (R) and/or circuit 911 (GN) between the LF brake anti-lock sensor and the anti-lock brake control module. If this fault is detected during the anti-lock brake control module's self-check after key "ON", the anti-lock brake warning indicator will come "ON" immediately. This is generally an indication of a constant wiring or component fault. However, the code is not written to the anti-lock brake control module's memory until the vehicle exceeds 6.4 km/in (4 mph). If the anti-lock brake warning indicator proves out normally (goes out after 2-3 seconds), and comes "ON" later when the vehicle is being driven, this is generally an indication of an intermittent wiring or component fault.

POSSIBLE CONTRIBUTING CONDITIONS:
- Poor connection at LF brake anti-lock sensor.
- Damaged or backed out connector pins.
- Open or shorted LF brake anti-lock sensor coil.
- Open or short conditions in circuit 912 (R) and/or 911 (GN).
- Improper LF brake anti-lock sensor cable routing causing an open or short.
- Defective LF brake anti-lock sensor electrical test circuit in the anti-lock brake control module.

H1- Check Fault Repeatability
- Turn ignition switch to "OFF".
- Connect scan tool to Data Link Connector (DLC).
- Turn ignition switch to "RUN".
- Clear all DTC's using the scan tool.
- Perform the Drive Cycle Test. Refer To Inspection and Verification.
- Retrieve DTC's from ABS memory using the scan tool.
- Is DTC C1155 retrieved?
YES - Go to H2.
NO - If System Pass is obtained concern is intermittent, go to H6.

H2- Check LF Brake ABS Sensor Circuit Resistance
- Disconnect connector C386 from anti-lock control module and connect breakout box and adapter.
- Measure the resistance between breakout box pin 32 and pin 19.
- Is the resistance between 2400 and 2800 ohms?
YES - Go to H3.
NO - If the resistance is less than 2400 ohms, go to H4.
- If the resistance is greater than 2800 ohms, Go to H5.

H3- Check Circuits
- Disconnect LF anti-lock sensor connector C118.
- Measure the resistance between breakout box pin 32 and pin 19.
- Measure the resistance between breakout box pin 32 and ground.
- Measure the resistance between breakout box pin 19 and ground.
- Does continuity exist?
YES - Repair circuit 912 (R) and/or 911 (GN) and go to H11.
NO - Reconnect the LF brake anti-lock sensor and go to H6.

H4- Isolate Low Resistance

RF Brake ABS Sensor. Measuring Resistance:

- Measure the resistance of the LF ABS sensor.
- Is resistance less than 2400 ohms?
YES - Replace the LF anti-lock sensor and go to H11.
NO - Repair circuit 912 (R) and/or Circuit 911 (GN) and go to H11.

H5- Isolate High Resistance
- Measure the resistance of the LF anti-lock sensor.
- Is resistance greater than 2800 ohms?
YES - Replace the LF anti-lock sensor and go to H11.
NO - Repair circuit 912 (R) and/or Circuit 911 (GN) and go to H11.

H6- Begin intermittent Diagnosis
- measure the resistance between breakout box pin 32 and pin 19.
- Is the resistance greater than 2800 ohms?
YES - Go to H5.
NO - Go to H7.

H7- Check for intermittent ABS Sensor Fault

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.

- Disconnect LF anti-lock sensor.
- Measure the resistance between the terminals of the LF anti-lock sensor connector.
- Is the resistance between 2400 and 2800 ohms?
YES - Go to H8.
NO - Replace the LF anti-lock sensor and go to H11.

H8- Check Circuits
- Measure the resistance between breakout box pin 32 and pin 19.
- Does continuity exist?
YES - Repair Circuit 912 (R) and/or circuit 911 (GN) and go to H11.
NO - Go to H9.

H9- Check Circuit for Intermittent Open
- Install a jumper wire between the two pins of the LF anti-lock sensor connector (harness side).
- Measure the resistance between breakout box pin 32 and Pin 19.

NOTE: Turn the beeper of the multimeter "ON" to indicate any changes in continuity as the test drive is performed.

- Drive the vehicle over a tough road while an assistant monitors the resistance.
- Is an intermittent high resistance found?
YES - Repair Circuit 912 (R) and/or Circuit 911 (GN) and go to H11.
NO - Go to H10.

H10- Conclude Intermittent Diagnosis
- Ensure that steps H1 and H5-H9 have been completed.
- Have Steps H1 and H5-H9 been completed.?
YES - If the concern is not resolved, replace the Left front anti-lock sensor and Go to H11.
NO - Return to the last step that was performed and continue.

H11- Verify repair
- Restore vehicle. Reconnect all components.
- 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 - Stop. Repair is complete.
NO - If original code is retrieved, repeat Pinpoint Test H.
- If a different DTC is retrieved, return to the DTC Index.