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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 >> Front Axle Will Not Engage

Front Axle Will Not Engage

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. Turn ignition to run position (engine off). Ensure vehicle is in 2WD mode. Using scan tool, read front axle actuator status. If scan tool displays actuator is closed, go to step 8). If scan tool does not display actuator is closed, go to next step.
  3. Turn ignition off. Disconnect front axle actuator connector. Turn ignition to run position (engine off). Connect test light between ground and Brown wire terminal at actuator connector. See WIRING DIAGRAMS  . If test light is on, go to step 5). If test light is off, go to next step.
  4. Locate and repair open in Brown wire circuit between front axle actuator connector and fuse. Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
  5. Connect self-powered test light between ground and Gray/Black wire terminal at actuator connector. Observe test light while using scan tool to engage front axle. If test light is on, go to step 8). If test light is off, go to next step.
  6. Turn ignition off. Disconnect ATC control module connectors C1 and C2. Connect jumper wire between ground and Gray/Black wire terminal at front axle actuator connector . See WIRING DIAGRAMS  . Connect test light between ground and Gray/Black wire terminal F4 at ATC control module connector C1. If test light is on, go to step 8). If test light is off, go to next step.
  7. Locate and repair open in Gray/Black wire circuit between ATC control module connector and front axle actuator connector. Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
  8. Disconnect front axle actuator connector. Using scan tool, read front axle actuator status. If scan tool displays actuator is closed, go to next step. If scan tool does not display actuator is closed, go to step 13).
  9. Locate and repair short to voltage in Black/White wire circuit between front axle actuator and ATC control module. If circuit is okay, replace ATC control module. See REMOVAL & INSTALLATION  . Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
  10. Connect self-powered test light between ground and Black wire terminal at front axle actuator connector. See WIRING DIAGRAM  . If test light is on, go to step 12). If test light is off, go to next step.
  11. Locate and repair open in Black wire circuit between front axle actuator connector and ground. Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
  12. Reconnect ATC control module connectors C1 and C2. Turn ignition to run position (engine off). Connect jumper wire between ground and Black/White wire terminal at front axle actuator connector. See WIRING DIAGRAMS  . Using scan tool, read front axle actuator status. If scan tool displays actuator is closed, go to next step. If scan tool does not display actuator is closed, go to step 14).
  13. Check for mechanical problems. If no problem is found, replace front axle actuator. Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
  14. Replace ATC control module. See REMOVAL & INSTALLATION  . Reconnect all disconnected components. When repair is complete, see ATC SYSTEM CHECK  .
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