Circuit Description
The body control module (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 theft deterrent relay to energize. |
| • | The steering column to unlock. |
| • | The BCM sends a message through the serial data line to the powertrain control module (PCM) to allow fuel enable processing to occur. |
When a BCM is replaced, the BCM must be programmed to accept the resistance value of the existing vehicle keys in order to allow PASS-Key® operation. When the BCM is replaced, the service replacement BCM is programmed to accept the first PASS-Key® resistance value detected. If the BCM is unable to detect a valid PASS-Key® resistance value, the BCM will never end the programming sequence and DTC B2735 will set.
Conditions for Setting the DTC
The BCM does not have a valid key pellet resistance in the memory.
Action Taken When the DTC Sets
| • | The BCM stores DTC B2735 in memory. |
| • | The BCM sends a message to the instrument cluster to illuminate the SECURITY indicator. |
| • | The BCM will disable the theft deterrent 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. |
| • | The steering column remains in the locked position. |
Conditions for Clearing the DTC
| • | The BCM detects a valid PASS-Key® resistance value when a service replacement BCM is initially programmed for the PASS-Key® system. |
| • | A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | Use the instrument panel cluster (IPC) clearing DTCs feature. |
| • | Use a scan tool. |
Diagnostic Aids
| • | If there is an open or a short on the PASS-Key® signal or ground circuit, the BCM will be unable to accept a valid PASS-Key® code when the program mode is activated. The vehicle will also exhibit a no crank condition. |
| • | Diagnose all other theft deterrent DTCs before attempting to diagnose DTC B2735, as this will affect the BCM's ability to properly read a PASS-Key® resistance value. |
| • | Clean the key resistor contacts of any foreign material. The foreign material could interfere with the key detection circuit, causing the BCM to be unable to program the PASS-Key® system and to set a DTC B2735. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Theft Deterrent System Schematics Connector End View Reference: Theft Deterrent System Connector End Views | |||
1 | Did you perform the Theft Deterrent Diagnostic System Check? | Go to Step 2 | |
2 |
Does the scan tool display DTC B2735 as a current DTC? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
3 |
Does the vehicle start and run? | Go to Step 7 | Go to Step 4 |
4 | Test the key resistor input circuit for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 5 |
5 | 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 7 | Go to Step 6 |
6 |
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 7 | -- |
7 |
Does the DTC reset? | Go to Step 2 | System OK |
