Test Description

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

2: A DTC P0602 indicates the ECM is not programmed.
4: Attempt to program the ECM. If the ECM fails to program a second time, replace the ECM.

DTC P0601, P0602, P0604, P0605, P0606

Step	Action	Yes	No
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Is DTC P0602 set?	Go to Step 3	Go to Step 5
3	Program the engine control module (ECM). Refer to Service Programming System (SPS) in Programming and Setup. Does DTC P0602 reset?	Go to Step 4	Go to Step 6
4	Ensure that all tool connections are secure. Ensure the programming equipment is operating correctly. Ensure the correct software and the correct calibration is used. Attempt to program the ECM. Refer to Service Programming System (SPS) in Programming and Setup. Does DTC P0602 reset?	Go to Step 5	Go to Step 6
5	Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement?	Go to Step 6	-
6	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	Go to Step 2	Go to Step 7
7	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK