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Home >> GMC >> 1998 >> C3500 HD 7.4 J, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 22 (Transfer Case - Diagnosis - New Venture 246) >> Symptom Tests >> Select Switch Inoperative

Select Switch Inoperative

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1998 GMC Yukon, 1998 GMC Suburban, 1998 GMC Pickup, 1998 GMC Cab & Chassis, and 1998 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
  1. If ATC system check was performed, go to next step. If system check was not performed, see ATC SYSTEM CHECK  .
  2. Connect scan tool to DLC. Turn ignition to run position (engine off). Using scan tool, actuate (turn on) all lights in select switch. If all lights are on, system is functioning properly at this time. If all lights are not on, go to next step.
  3. If any light is on in previous step, go to step 11). If no lights are on, go to next step.
  4. Connect self-powered test light between ground and Gray wire terminal at select switch connector C2. See WIRING DIAGRAMS  . If test light is on, go to step 6). If test light is off, go to next step.
  5. Locate and repair open in Black wire circuit between select switch connector C1 and ground. When repair is complete, see ATC SYSTEM CHECK  .
  6. Connect fused jumper wire (back probe) between ground and Gray wire terminal of select switch connector C2. If 4L light is on, go to step 8). If 4L light is off, go to next step.
  7. Replace select switch. See REMOVAL & INSTALLATION  . Reconnect all disconnected connectors. When repair is complete, see ATC SYSTEM CHECK  .
  8. Remove jumper wire. Connect fused jumper wire (back probe) between ground and Purple/White wire terminal F1 at ATC control module connector. See WIRING DIAGRAMS  . If 4L light is on, go to step 10). If 4L light is off, go to next step.
  9. Locate and repair open in Purple/White wire circuit between select switch and ATC control module connector. Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
  10. Replace ATC control module. See REMOVAL & INSTALLATION  . Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
  11. Connect fused jumper wire (back probe) between ground and cavity of inoperative light at select switch. See WIRING DIAGRAMS  for suspect light circuit to test. If suspect light is on, go to next step. If suspect light is off, go to step 7).
  12. Remove jumper wire from select switch. Connect fused jumper wire (back probe) between ground and cavity of inoperative light at ATC control module. See WIRING DIAGRAMS  for suspect light circuit to test. If suspect light is on, go to step 10). If suspect light is off, go to next step.
  13. Locate and repair open in appropriate wire circuit between select switch and ATC control module, corresponding to tested suspect light. Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
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