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Home › Lincoln › 1997 › Mark VIII Base › Repair and Diagnosis › Brakes › Traction Control › Anti-Lock Brake System › Diagnostic Trouble Code Tests › Test D: Poor Vehicle Tracking During Abs Function › No Warning Light

No Warning Light

  1. Bleed Brake System

    Turn air suspension switch off. Air suspension switch is located on left side of trunk. Raise vehicle on hoist. Bleed brake system. See BLEEDING BRAKE SYSTEM  . Remove vehicle from hoist, turn air suspension switch on and road test vehicle. If vehicle tracks poorly during ABS operation, go to next step. If vehicle tracks properly, system is functioning properly.

  2. Check Left Front ABS Valve Operation

    Turn air suspension switch off. Air suspension switch is located on left side of trunk. Turn ignition on. Connect New Generation Star (NGS) tester (007-00500) to Data Link Connector (DLC). DLC is located under dash, on right side of steering column. Raise vehicle. Set transmission selector in neutral and ensure all wheels turn freely. Enter active command ABS OUTPUT CONTROL. Trigger active command PMP MOTOR for 4 seconds. This requires trigger to be pressed twice. Each press activates motor for 2 seconds. Apply moderate pressure on brake pedal. If left front wheel will not rotate, go to next step. If left front wheel rotates, replace ABS Hydraulic Control Unit (HCU) and retest system.

  3. Check Left Front ABS Valve Release

    Trigger LF INLET and LF OUTLET ON. Using breaker bar, have assistant attempt to turn left front wheel within 2 seconds of each trigger press. If wheel does not turn, go to next step. If wheel turns, go to step 5).

  4. Check for DTC(s)

    Retrieve any stored DTC(s). If any DTC(s) are stored, service in numerical order. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTC(s) are stored, replace HCU and retest system.

  5. Check Right Front ABS Valve Operation

    Ensure air suspension switch is still off. Turn ignition on. Using NGS tester, enter active command ABS OUTPUT CONTROL. Trigger active command PMP MOTOR ON for 4 seconds. This requires trigger to be pressed twice. Each press activates motor for 2 seconds. Apply moderate pressure on brake pedal. If right front wheel cannot be rotated by assistant, go to next step. If right front wheel can be rotated, replace ABS Hydraulic Control Unit (HCU) and retest system.

  6. Check Right Front ABS Valve Release

    Trigger RF INLET and RF OUTLET ON. Using breaker bar, have assistant attempt to turn right front wheel within 2 seconds of each trigger press. If wheel does not turn, go to next step. If wheel turns, go to step 8).

  7. Check for DTC(s)

    Retrieve any stored DTC(s). If any DTC(s) are stored, service in numerical order. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTC(s) are stored, replace HCU and retest system.

  8. Check Left Rear ABS Valve Operation

    Ensure air suspension switch is still off. Turn ignition on. Using NGS tester, enter active command ABS OUTPUT CONTROL. Trigger active command PMP MOTOR ON for 4 seconds. This requires trigger to be pressed twice. Each press activates motor for 2 seconds. Apply moderate pressure on brake pedal. If left rear wheel cannot be rotated while pedal is depressed, go to next step. If left rear wheel can be rotated, replace ABS Hydraulic Control Unit (HCU) and retest system.

  9. Check Left Rear ABS Valve Release

    Trigger LR INLET and LR OUTLET ON. Using breaker bar, have assistant attempt to turn left rear wheel within 2 seconds of each trigger press. If wheel does not turn, go to next step. If wheel turns, go to step 11).

  10. Check for DTC(s)

    Retrieve any stored DTC(s). If any DTC(s) are stored, service in numerical order. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTC(s) are stored, replace HCU and retest system.

  11. Check Right Rear ABS Valve Operation

    Ensure air suspension switch is still off. Turn ignition on. Using NGS tester, enter active command ABS OUTPUT CONTROL. Trigger active command PMP MOTOR ON for 4 seconds. This requires trigger to be pressed twice. Each press activates motor for 2 seconds. Apply moderate pressure on brake pedal. If right rear wheel cannot be rotated while pedal is depressed, go to next step. If right rear wheel can be rotated, replace ABS Hydraulic Control Unit (HCU) and retest system.

  12. Check Right Rear ABS Valve Release

    Trigger RR INLET and RR OUTLET ON. Using breaker bar, have assistant attempt to turn right rear wheel within 2 seconds of each trigger press. If wheel does not turn, go to next step. If wheel turns, system is operating properly. Retest system.

  13. Check for DTC(s)

    Retrieve any stored DTC(s). If any DTC(s) are stored, service in numerical order. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTC(s) are stored, replace HCU and retest system.
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