P1634

CIRCUIT DESCRIPTION
The powertrain control module (PCM) receives three ignition inputs from the ignition switch: IGN 0, IGN 1, and CRANK Request. The PCM receives the IGN 0 input with the ignition switch in CRANK. The PCM uses a Class 2 ignition mode message, and the voltage input from 2 separate systems to test the IGN 0 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 Failure 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 1-12:

The number below refers to the step number on the diagnostic table.
2. The vehicle system voltage should be within 0.5 volts of ignition 0 signal.