P1634
CIRCUIT DESCRIPTIONEngine Control Schematics: PCM Power And Ground:
The PCM receives three ignition inputs from the ignition switch: IGN 0, IGN 1, and CRANK Request. The PCM receives the IGN 1 input with the ignition switch in RUN and START. The PCM uses a class 2 ignition mode message, and the voltage input from two separate systems to test the IGN 1 circuit. If the PCM detects an improper IGN 1 input, DTC P1634 will set.
CONDITIONS FOR RUNNING THE DTC
No Class 2 serial data circuit problem.
CONDITIONS FOR SETTING THE DTC
The PCM detects an improper IGN 1 input.
ACTION TAKEN WHEN THE DTC SETS
^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM will store conditions which were present when the DTC set as Fail Records information only.
Conditions for Clearing the DTC
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the scan tool Clear DTC Information function.
DIAGNOSTIC AIDS
If this DTC is intermittent check terminal contact at the PCM and the condition of the CKT 639 splice for an intermittent open condition.
TEST DESCRIPTION
