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 theft deterrent relay to energize. |
| • | The steering column to unlock. |
| • | The BCM sends a message through the serial data line to the 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 a DTC B2735 will set.
Conditions for Setting the DTC
The BCM is unable to detect a valid PASS-Key® code during BCM programming due to other malfunctions present (an open or a short in the PASS-Key® circuit).
Action Taken When the DTC Sets
| • | Stores a DTC B2735 in the BCM memory. |
| • | Sends a message to the IPC to display the SECURITY indicator. |
| • | The BCM will disable the theft deterrent relay. |
| • | The PCM will not allow fuel enable processing to occur. |
| • | Disables sampling of the PASS-Key® resistance for a time-out period of 3 minutes. |
| • | Does not disarm an armed UTD system. |
| • | 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 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 a DTC B2722 or B 2723 before attempting to diagnose a DTC B2735, as this will affect the BCMs 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. |
| • | Check for poor connections at the BCM and at the ignition lock cylinder. A poor connection could cause an open, an incorrect PASS-Key® resistance, or an intermittent malfunction. |
| • | If the DTC is a history DTC, the problem may be intermittent. Perform the tests while moving the related wiring, the connectors, and the key. This can often cause the malfunction to appear. Refer to Intermittents and Poor Connections . |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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Tests for other PASS-Key® DTCs stored in the BCM that would prevent the BCM from exiting the programming mode and cause this DTC to set.
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Tests if the PASS-Key® system was properly programmed.
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Tests for an intermittent or incorrect PASS-Key® resister reading due to an incorrect or malfunctioning ignition key.
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When the BCM is replaced, use a scan tool to perform the BCM RPO Reprogram procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration .
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the BCM Diagnostic System Check? | -- | Go to Step 2 | |||||
Does the scan tool display DTC B2722 or B2723? | -- | Go to Step 3 | ||||||
Program the PASS-Key® System. Refer to PASS-Key Programming . Did you complete the programming procedure? | -- | Go to Step 6 | -- | |||||
Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 5 | |||||
|
Important: Perform the BCM RPO Reprogram procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration . Replace the BCM. Refer to Body Control Module Replacement . Did you complete the replacement? | -- | Go to Step 6 | -- | |||||
6 |
Does the DTC reset? | -- | Go to Step 4 | System OK |
