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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) >> DTC Tests >> DTC C0309: Shift Motor Circuit High >> Testing

DTC C0309: Shift Motor Circuit High: Testing

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 off. Connect scan tool to DLC. Turn ignition to run position (engine off). Using scan tool, record all freeze frame and failure records. Turn ignition off. Disconnect ATC control module connectors C1 and C2. Disconnect transfer case connector for shift motor. Turn ignition to run position (engine off). Connect test light between ground and Black wire terminal "A" at transfer case. See WIRING DIAGRAMS  . If test light is on, go to next step. If test light is off, go to step 4).
  3. Locate and repair short to voltage in Black wire circuit. When repair is complete, go to step 7).
  4. Connect test light between ground and Red wire terminal "B" at transfer case. If test light is on, go to next step. If test light is off, go to step 6).
  5. Locate and repair short to voltage in Red wire circuit. When repair is complete, go to step 7).
  6. Replace ATC control module. See REMOVAL & INSTALLATION  . When replacement is complete, go to next step.
  7. Turn ignition off. Reconnect all disconnected components. Set parking brake. Start and run engine at idle. Shift transmission to "N" position. Shift transfer case between all modes, allowing time between each mode shift for transfer case to complete shift request. Using scan tool, select "Specific DTC" and enter DTC C0309. If test runs and passes, system is functioning properly. If test does not run and pass, repeat test from step 1).
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