Diagnostic Aids

An over charging condition may set this DTC. Refer to Charging System Test 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 - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Is DTC P0560 set?	Go to DTC P0560 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 powertrain control module (PCM). Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. 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 - Vehicle in Vehicle DTC Information	System OK