04 Buick Rendezvous and Pontiac Aztek 3.4 LA1 Intermittent Crank, No Start or Stalls MIL/DTCs P0443 P0645 P1689 - kw B2712 block 3.4 C0240 center communication connector control DIC driveability DTC

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

The customer concern may be an intermittent stall while driving or intermittent crank no start. There may be MIL/DTCs P0443 P0645, P1689, B2712, C0240, U1000, and U1040. The codes may be current or history and may not be able to duplicate.

Technical Assistance cases have indicated a possible cause of this condition could be poor wire crimp connections, loose fitting terminals in the under hood fuse block, terminal pin corrosion, or a malfunctioning ignition 1 relay.

1. Check the IGN1 MAIN and ECM IGN 1 MAIN fuses located in the under hood relay center for the following conditions and repair as necessary:

•	Terminal corrosion

•	Poor pin fit

•	Terminals backing out of fuse block

•	Poor terminal/wire crimp

2. Check Ground G111 for the following conditions and repair as necessary:

•	Loose attachment bolt

•	Poor terminal/wire crimp

3. Remove Ignition 1 relay from the under hood fuse block and inspect for the following conditions and repair as necessary:

•	Terminal corrosion

•	Poor pin fit

•	Terminals backing out of fuse block

•	Poor terminal/wire crimp

If no concern is found with the above components, replace the Ignition 1 relay and evaluate the vehicle.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(2004 Buick Rendezvous) and (2004 Pontiac Aztek)

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