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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 512 (Engine Controls/Fuel - 5.3L, 6.0L, 6.2L - DTC P0010 To DTC P0358) >> Diagnostic Information and Procedures >> DTC P0120-P0123, P0220, P0222, P0223, or P2135 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE:

    Disconnecting the throttle body harness connector causes additional DTCs to set.

  1. Ignition OFF, and all vehicle systems OFF, disconnect the harness connector at Q38 throttle body assembly. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 5 Ω between the low reference circuit terminal C and ground.
    • If 5 Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
    2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 engine control module.
    • If less than 5 Ω 
  3. Ignition ON.
  4. Test for 4.8-5.2 V between the 5 V reference circuit terminal E and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
    2. Test for infinite resistance between the 5 V reference circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the 5 V reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 engine control module.
    • If greater than 5.2 V 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
    2. Test for less than 1 V between the 5 V reference circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K20 engine control module.
    • If between 4.8-5.2 V 
  5. Ignition ON.
  6. Test for less than 1 V between the TP sensor 1 signal circuit terminal D and ground.
    • If 1.0 V or greater 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K20 engine control module.
    • If 1.0 V or less 
  7. Install a 3 A fused jumper wire between TP sensor 1 signal circuit terminal D and the 5 V reference circuit terminal E.
  8. Verify the scan tool TP sensor 1 voltage parameter is greater than 4.8 V.
    • If 4.8 V or less 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
    2. Test for infinite resistance between the signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 engine control module.
    • If 4.8 or greater 
  9. Test for 4.8-5.2 V between the TP sensor 2 signal circuit terminal F and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
    2. Test for infinite resistance between the signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K20 engine control module.
    • If greater than 5.2 V 
    1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K20 engine control module.
    • If between 4.8-5.2 V 
  10. Test or replace the Q38 throttle body assembly.
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