Diagnostic Aids

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

An over charging condition may set this DTC. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical.

Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Repair the circuits as necessary. Refer to Intermittent Conditions .

DTC P1640

Step	Action	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module (PCM) Connector End Views
1	Did you perform the Diagnostic System Check-Engine Controls?	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Is DTC P0560 set?	Go to Diagnostic System Check - Engine Electrical in Engine Electrical	Go to Step 3
3	With a scan tool select the Output Driver Data list. Observe the parameters on the scan tool. Do any parameters indicate a fault present?	Go to Step 4	Go to Step 5
4	Test for a short to voltage on the control circuit of the component that indicated a fault. Did you find and correct the condition?	Go to Step 6	Go to Step 5
5	Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement . Did you complete the replacement?	Go to Step 6	-
6	Use the scan tool in order to clear the DTCs. Start the engine. Allow the engine to idle until the engine reaches normal operating temperature. Select DTC and the Specific DTC function. Enter the DTC number which was set. Operate the vehicle, with the Conditions for Setting the DTC, until the scan tool indicates the diagnostic ran. Does the scan tool indicate that the diagnostic passed?	Go to Step 7	Go to Step 2
7	With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed?	Go to Diagnostic Trouble Code (DTC) List	System OK