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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 508 (Engine Controls/Fuel - 5.3L, 6.0L, 6.2L - DTC P0420 To DTC P3449 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P2120, P2122, P2123, P2125, P2127, P2128, or P2138 >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B107 accelerator pedal position sensor. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 5 Ω between the appropriate low reference circuit terminal listed below and ground.
    • APP sensor 1 low reference circuit terminal F or 4
    • APP sensor 2 low reference circuit terminal A or 5
    • 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 appropriate 5 V reference circuit terminal listed below and ground.
    • APP sensor 1 5 V reference circuit terminal D or 2
    • APP sensor 2 5 V reference circuit terminal C or 1
    • 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. Verify the scan tool APP sensor 1 and APP sensor 2 voltage parameters are less than 0.3 V.
    • If 0.3 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 terminal listed below and ground.
    • APP sensor 1 signal circuit terminal E or 3
    • APP sensor 2 signal circuit terminal B or 6
    • 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 less than 0.3 V 
  6. Install a 3 A fused jumper wire between the appropriate signal circuit terminal listed below and the 5 V reference circuit terminal C or 1.
    • APP sensor 1 signal circuit terminal E or 3
    • APP sensor 2 signal circuit terminal B or 6
  7. Verify the scan tool APP sensor 1 or APP sensor 2 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 terminal 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 4.8 V 
  8. Test or replace the B107 accelerator pedal position sensor.
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