Circuit Description
The body control module (BCM) supplies a 5 volt signal and a ground circuit for the PASS-Key® system. When the Ignition key is inserted into the ignition cylinder and turned to the ON position the BCM reads the PASS-Key® resistance value. The BCM compares the resistance value of the key resistance to the valid resistance programmed into the BCM. If the correct value is read, the BCM sends a class 2 message containing the enable password to the powertrain control module (PCM).
Conditions for Setting the DTC
| • | The voltage level at the BCMs ignition key resistor signal circuit is incorrect during a start attempt, signaling that an open or short to voltage is present. |
| • | The voltage level at the BCMs ignition key resistor signal circuit is incorrect when the ignition is in the ON position for 1 second. |
Action Taken When the DTC Sets
Important: If the PASS-Key® system detects an open or short when the ignition switch is in the ON position, the BCM will default to fail enable mode. The vehicle will not stall or stop running. If the BCM is in fail enable state when the ignition is turned OFF, it will remain fail enable until the next time the vehicle is started. If the BCM is fail enable the PASS-Key® system is NOT active and the vehicle will start.
| • | The BCM sends a class 2 message to the instrument cluster to illuminate the SECURITY indicator. |
| • | The BCM sends a class 2 message containing the disable password to the PCM. |
| • | The vehicle will not start. |
| • | The BCM disables sampling of the PASS-Key® resistance value 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 starting and fuel delivery systems. 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 to ground on the PASS-Key® ignition key resistor signal circuit, the vehicle will exhibit a no crank condition. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Referance: Theft Deterrent System Schematics | |||
1 | Did you perform the Theft Deterrent Diagnostic System Check? | Go to Step 2 | |
2 |
Does the scan tool display B2957 as a current DTC? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
3 | Inspect the ignition key for dirt or obvious damage. Does the ignition key appear dirty or damaged? | Go to Step 9 | Go to Step 4 |
Does the vehicle start? | Go to Step 8 | Go to Step 5 | |
5 | Test the ignition key resistor signal circuit for an open or short to voltage. Did you find and correct the condition? | Go to Step 12 | Go to Step 6 |
6 | Test the low reference circuit for an open or short to voltage. Did you find and correct the condition? | Go to Step 12 | Go to Step 7 |
7 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 11 |
8 | Inspect for poor connections at the harness connector of the ignition lock cylinder. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
9 | Clean or replace the ignition key as necessary. Refer to Replacing Keys . Did you complete the repair? | Go to Step 12 | -- |
10 | Replace the ignition lock cylinder. Refer to Ignition Lock Cylinder Replacement - On Vehicle in Steering Wheel and Column - Tilt. Did you complete the replacement? | Go to Step 12 | -- |
11 |
Important: When replacing the BCM, perform the relearn procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System. Replace the BCM. Refer to Body Control Module Replacement in Body Control System. Did you complete the repair? | Go to Step 12 | -- |
12 |
Does the DTC reset? | Go to Step 2 | System OK |
