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Home >> Chevrolet >> 2009 >> Chevy Express G2500, Van Cargo Extended, 6.6 6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 6.6L LMM - DTC P1224 To DTC P2463 >> DTC P154C >> Circuit/System Testing

Circuit/System Testing

IMPORTANT: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
  1. Test the IAH current signal circuit between IAH terminal 4 X1 and GPCM terminal 29 X2 for an open, a short to ground, or a short to voltage:
  2. Ignition OFF, disconnect the X1 harness connector of the IAH. Connect any other circuits that were previously disconnected.
    3. IMPORTANT: Set the DMM to the 4V DC hertz scale.
  3. Turn ON the ignition. With a DMM measure between command 2 circuit terminal 3 of the connector and a good ground for 0.78-1.1 Hz.
    • If the DMM does not measure between 0.78-1.1 Hz, replace the GPCM.
    4. IMPORTANT:
    • Do not supply 12 volts to terminal 2 on the IAH for more than 20 seconds.
    • Set the DMM to the 4V DC hertz scale.
  4. Turn OFF the ignition. Install a jumper wire between temperature signal circuit terminal 1 of the connector and the corresponding terminal on the IAH.
  5. Install a jumper wire between the IAH harness command 2 circuit terminal 3 of the connector and the corresponding terminal on the IAH.
  6. Supply 12 volts to terminal 2 on the IAH.
  7. Turn ON the ignition. Measure for 1 hertz on terminal 4 at the IAH.
    • If 0.7-1.1 hertz is measured on terminal 4, replace the GPCM.
    • If 0.7-1.1 hertz is not measured on terminal 4, replace the IAH.
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