B2958

CIRCUIT DESCRIPTION
The BCM supplies a 5 volt signal and a ground circuit for the PASS-Key system. This allows the BCM to detect PASS-Key resistance values. Inserting the PASS-Key (with resistor pellet) in the ignition lock cylinder completes the PASS-Key circuit. Contacts in the ignition lock cylinder mate with the pellet contacts. The BCM compares the resistance value of the key pellet to the valid resistance programmed into the BCM. If the proper resistance value is read, the BCM allows the following functions to occur:
- The crank relay to energize.
- The BCM sends a message through the serial data line to the PCM to allow fuel delivery to occur.

If the resistance value is incorrect, a malfunction is present and a DTC will set.

CONDITIONS FOR SETTING THE DTC
- The voltage level sampled at the BCMs PASS-Key signal circuit is incorrect, signaling that an invalid PASS-Key resistance was detected and a short is present.
- This condition must be present for 1 second.

ACTION TAKEN WHEN THE DTC SETS
- The BCM sends a message to the instrument cluster to illuminate the SECURITY indicator.
- The PCM disables the crank relay.
- The PCM will not allow fuel delivery to occur.
- The BCM disables sampling of the PASS-Key resistance for a time-out period of 3 minutes.

CONDITIONS FOR CLEARING THE DTC
- This DTC requires an ignition cycle in order to change from current to history.
- The BCM detects a valid PASS-Key resistance value on the PASS-Key signal circuit.
- A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
- Use a scan tool.

DIAGNOSTIC AIDS
- If the key resistor pellet is incorrect, there will be no outputs to the crank relay or to the PCM fuel delivery system. This state will last about 3 minutes. If a key is inserted, or the ignition is turned ON again before the 3 minute time frame is complete, the timer will reset to 3 minutes. Disconnecting the battery will not clear the timer sequence, but the timer will reset to 3 minutes when the battery power is restored. Even if a proper key is inserted during one of the time periods, the vehicle will not start until the total time period has elapsed.
- If there is a short between the PASS-Key signal and ground circuit, or a short to ground on the PASS-Key signal circuit, the vehicle will exhibit a no crank condition.

TEST DESCRIPTION

Steps 1-11:

The number(s) below refer to the step number(s) on the diagnostic table.
4. This test verifies the integrity of the key resistor circuits between the ignition switch and the BCM.