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. |
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 low, signaling that an invalid PASS-Key® resistance was detected, and a short to ground is present. |
| • | This condition must be present for 1 second. |
Action Taken When the DTC Sets
| • | Stores a DTC B2722 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
| • | 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 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
| • | The following conditions may cause an intermittent malfunction: |
| - | There is an intermittent short to ground on PASS-Key® signal circuit. |
| - | If there is an intermittent short between the PASS-Key® signal and ground circuit; the BCM would interpret this as a short to ground condition. |
| - | The PASS-Key® resistor is shorted. |
| • | If the key resistor pellet is incorrect, there will be no BCM outputs to the theft deterrent relay or to the PCM. 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 lapsed. |
| • | 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. |
| • | 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 PASS-Key® Resister Signal data using a scan tool.
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Tests the PASS-Key® Resister Signal data with the PASS-Key® ignition switch connector disconnected. The scan tool will display PASS-Key® Resister Signal voltage as 5 volts with the PASS-Key® ignition switch connector disconnected.
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Tests the PASS-Key® Resister Signal data with a jumper wire between the signal and ground circuit. The scan tool will display PASS-Key® Resister Signal voltage as 0 volts with the PASS-Key® circuits jumpered.
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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 indicate that the PASS-Key® Resistor Signal parameter is within the specified range? | 0.5-4.5 V | Go to Diagnostic Aids | Go to Step 3 | |
Does the scan tool indicate that the PASS-Key® Resistor Signal parameter is greater than the specified value? | 4.5 V | Go to Step 4 | Go to Step 5 | |
Does the scan tool indicate that the PASS-Key® Resistor Signal parameter is less than the specified value? | 0 V | Go to Step 8 | Go to Step 6 | |
5 | Test the signal circuit of the PASS-Key® system for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 |
6 | Test the signal circuit of the PASS-Key® system for a short to voltage, 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 12 | Go to Step 7 |
7 | Test the ground circuit of the PASS-Key® system 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 12 | Go to Step 9 |
8 | Inspect for poor connections at the PASS-Key® harness connector at the ignition switch. 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 | 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 |
10 | Perform the ignition lock cylinder test. Refer to Ignition Key Lock Cylinder Test . Did you find and correct the condition? | -- | Go to Step 12 | Go to Diagnostic Aids |
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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 12 | -- | |
12 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
