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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 53 (SHIFT INTERLOCK SYSTEMS)SYMPTOM TESTSTEST A: REVERSE LOCKOUT SYSTEM INOPERATIVE
1999 GMC Forward Control 5.7 R, Automatic

Test A: Reverse Lockout System Inoperative

1999 GMC Forward Control 5.7 R, AutomaticSECTION Test A: Reverse Lockout System Inoperative
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora and 2001 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit reference, see CONNECTOR IDENTIFICATION  and WIRING DIAGRAMS  .
  1. Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition switch to ON position. Press and hold the brake pedal. Attempt to move the gearshift lever to Reverse position. Does the gearshift lever move to the Reverse position? If so, go to step  6 . If not, go to next step.
  3. Turn ignition switch to the OFF position. Install a scan tool. Turn ignition switch to the ON position. With a scan tool, observe the reverse lockout drive parameter in the DIM output display data list. Does the scan tool display an OFF status? If so, go to next step. If not, go to step  11 .
  4. Turn ignition switch to the OFF position. Disconnect the reverse lockout solenoid. Turn ignition switch to the ON position. Press and hold the brake pedal. Move the gearshift lever to the Neutral position. Attempt to move the gearshift lever to the Reverse position. Does the gearshift lever move to the Reverse position? If so, go to next step. If not, go to step  10 .
  5. Test the reverse lockout solenoid control circuit (Light Green wire) for a short to ground. Did you find and correct the condition? If so, go to step  15 . If not, go to step  11 .
  6. With a scan tool, command the reverse lockout drive parameter ON in the DIM special functions output control data list. Press and hold the brake pedal. Move the gearshift lever to the Neutral position. Attempt to move the gearshift lever to the Park position. Does the gearshift lever move to the Reverse position? If so, go to next step. If not, check for an intermittent condition. See SYMPTOM DIAGNOSIS  .
  7. Turn ignition switch to the OFF position. Disconnect the reverse lockout solenoid. Connect a test light between ground and the reverse lockout solenoid voltage supply circuit (Dark Green/White wire). Turn ignition switch to the ON position. Does the test light illuminate? If so, go to next step. If not, go to step  12 .
  8. Turn ignition switch to the OFF position. Connect a test light between the reverse lockout solenoid voltage supply circuit (Dark Green/White wire) and the reverse lockout solenoid control circuit (Pink/Black wire) at the reverse lockout relay connector. Turn ignition switch to the ON position. With a scan tool, command the reverse lockout drive ON and OFF several times. Does the test light turn ON and OFF with each command? If so, go to step  10 . If not, go to next step.
  9. Test for an open or short to battery voltage in the reverse lockout solenoid control circuit (Pink/Black wire). Did you find and correct the condition? If so, go to step  15 . If not, go to step  11 .
  10. Inspect the reverse lockout solenoid for poor connections. Did you find and correct the condition? If so, go to step  15 . If not, go to step  13 .
  11. Inspect the DIM for poor connections. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. Did you find and correct the condition? If so, go to step  15 . If not, go to step  14 .
  12. Repair the open in the reverse lockout solenoid voltage supply circuit (Brown wire). After repairs, go to step  15 .
  13. Replace the reverse lockout solenoid. See FLOOR SHIFT CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After repairs, go to step  15 .
  14. Replace the DIM. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After repairs, go to next step.
  15. Road test vehicle over 5 MPH for 15 seconds or longer, then retest reverse lockout system operation. Did you find and correct the condition? If so, system is okay. If not, go to step  2 .
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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