LEMON Manuals: Even more car manuals for everyone
Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 365 (Engine Controls And Fuel - Hybrid (LZ1) - DTC P0351 Through DTC P3449 And Troubleshooting) >> Diagnostic Information and Procedures >> DTC P0685, P0689, P0690, or P1682 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:

You must perform the Circuit/System Verification before proceeding with Circuit/System Testing unless sent here from Engine Cranks But Does Not Run.

  1. Ignition OFF, disconnect the KR75 powertrain relay.
  2. Verify a test lamp illuminates between ground and the relay circuit terminals listed below:
    • Terminal 85
    • Terminal 30
    • If the test lamp does not illuminate, test the relay battery voltage circuit for an open/high resistance.
    3. NOTE:
    • The ignition voltage circuit is between the powertrain relay and the ECM. The ignition voltage circuit is a feedback circuit.
    • High resistance in the circuit/underhood fuse block for either the powertrain relay or the run/crank relay can cause DTC P1682 to set.
  3. Ignition ON, verify that a test lamp does not illuminate between the ignition voltage circuit terminal 87 and ground.
    • If the test lamp illuminates, test the ignition voltage circuit for a short to voltage.
  4. Connect a 20 A fused jumper wire between the relay switch B+ circuit terminal 30 and the relay switch ignition voltage circuit terminal 87.
  5. Ignition ON, observe the scan tool EC Ignition Relay Feedback Signal parameter. The ECM should communicate, and the parameter should display B+.
    • If not the specified value, or the ECM does not communicate, test the ignition voltage circuit between the powertrain relay and the ECM for a short to ground or for an open/high resistance. If the circuit/connections test normal, replace the K20 ECM.
  6. Ignition OFF, connect a DMM set to the diode setting between control circuit terminal 86 and ground. Verify the DMM displays OL.
    • If not the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
  7. Ignition ON, verify the DMM displays less than 1 V.
    • If not the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  8. If all circuits test normal, replace the KR75 powertrain relay.
scientia non olet · About LEMON Manuals