P1634

CIRCUIT DESCRIPTION
The powertrain control module (PCM) receives two ignition inputs from the ignition switch: IGN 0, IGN 1, and a Class II message from the power mode master (PMM) module. The PCM receives the IGN 0 input with the ignition switch in OFF and RUN. The PCM uses a PMM Class II message, and the voltage input from the ignition switch to lest the IGN 1 circuit. If the PCM detects an improper IGN 1 input, DTC P1634 will set.

CONDITIONS FOR RUNNING THE DTC
No Class II 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.

TEST DESCRIPTION

Steps 1-8:

Steps 9-14:

The numbers below refer to the step numbers on the diagnostic table.
2. The vehicle system voltage should be within 0.5 volts of Ignition 0 Signal.