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Home >> Cadillac >> 2018 >> Escalade Base, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 11 (Engine Controls And Fuel - 6.0L (L96) - DTC P0351 To DTC P2636 And Diagnostic Information And Procedures) >> Diagnostic Information And Procedures >> DTC P2122, P2123, P2127, P2128 Or P2138: Accelerator Pedal Position (APP) Sensor(s) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Suburban 3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  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 each low reference circuit terminal listed below and ground.
    • Low reference circuit terminal 4
    • Low reference circuit terminal 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.
    • Go to next step: If less than 5 Ω 
  3. Ignition ON.
  4. Test for 4.8 - 5.2 V between each 5 V reference circuit terminal listed below and ground.
    • 5 V reference circuit terminal 2
    • 5 V reference circuit terminal 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.
    • Go to next step: If between 4.8 - 5.2 V 
  5. Verify each APP sensor voltage parameter is less than 0.2 V.
    • If 0.2 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 3
    • APP sensor 2 signal circuit terminal 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.
    • Go to next step: If less than 0.2 V 
  6. Connect a 3 A fused jumper wire between the appropriate signal circuit terminal listed below and a 5 V reference circuit terminal 2 or 1.
    • APP sensor 1 signal circuit terminal 3
    • APP sensor 2 signal circuit terminal 6
  7. Verify the scan tool APP Sensor 1 or 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.
    • Go to next step: If greater than 4.8 V 
  8. Test or replace the B107 Accelerator Pedal Position Sensor.
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