J

Poor Vehicle Tracking During ABS Function (Warning Indicator "OFF")

J1 - Bleed Brake System
- Turn air suspension switch "OFF", if equipped.
- Bleed brake system. Refer to Service and Repair. Service and Repair
- Turn air suspension switch "ON", if turned "OFF".
- Road Test vehicle.
- Does vehicle track poorly ?
YES - Go to J2.
NO - Condition corrected.

J2 - Check LH Front Anti-lock Valve Operation
- Turn air suspension switch "OFF", if equipped.
- Turn ignition switch to "RUN".
- Lift vehicle and place transmission in "NEUTRAL".
- Rotate all wheels to make sure they turn freely. If they don't, test for binding parking brake or incomplete brake return. Refer to Brakes and Traction Control System Diagnosis. Testing and Inspection
- Use NGS to put ABS control module into diagnostic mode.
- Use NGS active command PMP MOTOR to command pump motor to run for four seconds (press trigger twice since each input will run motor for two seconds). This will make sure the accumulators are empty.
- Apply moderate brake pedal effort and have an assistant check that the LH front wheel will not turn. If wheel turns, replace brake pressure control valve block.
- Use NGS active command LF OUTLET to trigger LH front valve to energize.
- Have an assistant check LH front wheel immediately after pressing trigger (NGS will only energized valve for two seconds per trigger input).
- Did LH front wheel turn freely (with a 0.6 meter (2 foot) lever such as a tire iron) while valves were energized ?
YES - Go to J3.
NO - Verify no anti-lock brake control module internal failure DTC's are stored by running the on-demand self test. If no DTC's are received, replace Brake Pressure Control Valve Block. Refer To Brake Pressure Control Valve Block. Service and Repair

J3 - Check RH Front Anti-lock Valve Operation
- Use NGS active command PMP MOTOR to command pump motor to run for four seconds (press trigger twice since each input will run motor for two seconds). This will make sure the accumulators are empty.
- Apply moderate brake pedal effort and have an assistant check that the RH Front wheel will not turn. If wheel turns, replace brake pressure control valve block.
- Use NGS active command RF OUTLET to trigger RH Front valve to energize.
- Have an assistant check RH front wheel immediately after pressing trigger (NGS will only energized valve for two seconds per trigger input).
- Did RH front wheel turn freely (with a 0.6 meter (2 foot) lever such as a tire iron) while valves were energized ?
YES - Go to J4.
NO - Verify no anti-lock brake control module internal failure DTC's are stored by running the on-demand self test. If no DTC's are received, replace Brake Pressure Control Valve Block.

J4 - Check LH Rear Anti-lock Valve Operation
- Use NGS active command PMP MOTOR to command pump motor to run for four seconds (press Trigger twice since each input will run motor for two seconds). This will make sure the accumulators are empty.
- Apply moderate brake pedal effort and have an assistant check that the LH rear wheel will not turn. If wheel turns, replace brake pressure control valve block.
- Use NGS active command LR OUTLET to trigger LH rear valve to energize.
- Have an assistant check LH rear wheel immediately after pressing trigger (NGS will only energized valve for two seconds per trigger input).
- Did LH rear wheel turn freely (with a 0.6 meter (2 foot) lever such as a tire iron) while valves were energized ?
YES - Go to J5.
NO - Verify no anti-lock brake control module internal failure DTC's are stored by running the on-demand self test. If no DTC's are received, replace brake pressure control valve block.

J5 - Check RH Rear Anti-lock Valve Operation
- Use NGS active command PMP MOTOR to command pump motor to run for four seconds (press trigger twice since each input will run motor for two seconds). This will make sure the accumulators are empty.
- Apply moderate brake pedal effort and have an assistant check that the RH rear wheel will not turn. If wheel turns, replace Brake Pressure Control Valve Block.
- Use NGS active command RR OUTLET to trigger RH Rear valve to energize.
- Have an assistant check RH rear wheel immediately after pressing trigger (NGS will only energized valve for two seconds per trigger input).
- Did RH rear wheel turn freely (with a 0.6 meter (2 foot) lever such as a tire iron) while valves were energized ?
YES - Verify no anti-lock brake control module internal failure DTC's are stored by running the on-demand self test. Re-verify symptom.
NO - Verify no anti-lock brake control module internal failure DTC's are stored by running the on-demand self test. If no DTC's are received, replace Brake Pressure Control Valve Block.