Thursday, June 16, 2011

GMC Envoy Denali

GMC Envoy will not start/ crank over. Trouble codes P0121, P1516, P2101, P2135 and P2176 are present.
Already tested voltage at the Powertrain Control Module (PCM) C1 Blue connector terminal 51 Orange/Black wire from the park/neutral switch, battery voltage Key On, Engine Off (KOEO) and cranking. Tested voltage backprobed at the PCM C1 terminal 52 Purple wire, battery voltage in the crank position.

Further Tests:

1. Test voltage backprobed at the PCM C1 terminal 13 Yellow/Black wire starter relay control. Should be battery voltage KOEO, ground when cranking.

2. If the voltage stays high during crank, test the PCM powers/grounds.

3. Check the Transmission Range (TR) switch status with a scan tool. It must indicate Park or Neutral for the engine to start.

4. Check the Vehicle Theft Deterrent (VTD) Fuel Disable status with a scan tool. If it displays “active” during crank, check for theft deterrent system trouble codes.

5. Unplug the throttle body. If the engine now cranks, troubleshoot the throttle body DTC's.

Potential Causes:

Powertrain Control Module (PCM)

Park Neutral Position (PNP) Switch

Throttle Body

Confirmed Fix:

Replaced Throttle Body

Tech Tips:

G108 is located on the lower left side of the engine block, near the front of the engine.
I hope this helps get your GMC Envoy back on the road

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