LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 2018 >> Acadia Denali, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 118 (Engine Controls And Fuel - 3.6L (LF4 LGX) - DTC P0685 LGX To DTC P3436 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P1516, P2101, P2119, or P2176: Throttle Actuator Position (LF4) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2016 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE:

    Disconnecting throttle body harness connectors may cause additional DTCs to set.

  1. Ignition OFF, disconnect the in-line harness connector X164 to the Q38 Throttle Body.
    2. NOTE:
    • Ensure that the testing is done on the ECM side of the in-line connector.
    • Before testing each circuit, the ignition must be OFF and the ECM completely powered down.
    • The test lamp must be connected to the circuit before turning the ignition ON, or incorrect diagnosis may occur.
  2. Connect a test lamp between a motor control circuit listed below and ground.
    • TAC Motor Control Open circuit terminal 1
    • TAC Motor Control Closed circuit terminal 2
    3. NOTE:
    • The test lamp should illuminate then immediately turn OFF as the ignition is switched to the ON position.
    • Be prepared to observe the test lamp as the ignition is switched ON.
  3. Ignition ON, verify that a test lamp does not illuminate continuously after the ignition is switched to ON.
    • If the test lamp illuminates continuously 
    1. Ignition OFF, disconnect the appropriate harness connector at the K20 Engine Control Module and remove the test lamp, ignition ON.
    2. Test for less than 1 V between the control 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 the test lamp is always OFF 
    1. Ignition OFF, disconnect the appropriate harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the control 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 control 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 the test lamp illuminates then turns OFF with ignition ON. 
  4. Ignition OFF, set the DMM to the 40 V scale or higher, select the Min/Max Recording Mode, and set the Peak Min/Max response time to 1 ms or faster.
    5. NOTE:
    • The DMM Min/Max Recording Mode and the response time of 1 ms or faster must be reset after testing each circuit or a lower voltage will be recorded.
    • The ignition must be OFF and the ECM completely powered down before testing each circuit or a lower voltage will be recorded.
  5. Verify the Max voltage is within 3 V of B+, while using DMM Min/Max Recording Mode function on each control circuit listed below and ground, as the ignition is turned ON.
    • TAC Motor Control Open circuit terminal 1
    • TAC Motor Control Closed circuit terminal 2
    • If not within 3 V of B+ 
    1. Ignition OFF, disconnect the appropriate harness connector at the K20 Engine Control Module.
    2. Test for less than 2 Ω in the control 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 within 3 V of B+ 
    6. NOTE:

    Verify the integrity of the jumper harness to the Q38 Throttle Body before replacing the component.

  6. Test or replace the Q38 Throttle Body assembly.
scientia non olet · About LEMON Manuals