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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 2000 (Automatic Transmission - 4T45-E - DTC P0973 To DTC P2797) >> DTC P1808 or P1809 (Hybrid) >> Circuit/System Testing (Hybrid)

Circuit/System Testing (Hybrid)

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: If the above Circuit/System Verification results in inverted operation, check for a calibration/switch mismatch.
IMPORTANT: Additional DTCs may set when disconnecting the automatic transmission inline 20-way connector.

Normally-Open TFP Switch A:

  1. Ignition OFF, disconnect the AT 20-way inline harness connector at the transmission.
  2. Ignition ON, verify the scan tool ECM TFP Switch A parameter is Low.
    • If not the specified value, test the signal circuit terminal N for a short to ground. If the circuit tests normal, replace the ECM.
  3. Install a 3A fused jumper wire between the signal circuit terminal N to ground. Verify the scan tool TFP Switch A is High.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Test for less than 1 ohm of resistance between terminal N of the AT 20-way connector and terminal A of the TFP manual valve position switch.
    • If greater than the specified range, replace the Internal Transmission Harness.
  5. If all circuits test normal, test or replace the TFP switch.

Normally-Closed TFP Switch A:

  1. Ignition OFF, disconnect the AT 20-way inline harness connector at the transmission.
  2. Ignition ON, verify the scan tool ECM TFP Switch A parameter is High.
    • If not the specified value, test the signal circuit terminal N for a short to ground. If the circuit tests normal, replace the ECM.
  3. Install a 3A fused jumper wire between the signal circuit terminal N to ground. Verify the scan tool TFP Switch A is Low.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Test for less than 1 ohm of resistance between terminal N of the AT 20-way connector and terminal A of the TFP manual valve position switch.
    • If greater than the specified range, replace the Internal Transmission Harness.
  5. If all circuits test normal, test or replace the TFP switch.
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