Circuit Description
The Passlock™ theft deterrent system contains a Passlock™ sensor. The Passlock™ sensor is part of the ignition lock cylinder assembly. The body control module (BCM) provides voltage (B+) to the Passlock™ sensor through circuit 1459 when the ignition switch is in the accessory, on, or start. The BCM also provides ground to the Passlock™ sensor through circuit 1835. The Passlock™ sensor interfaces with the BCM through the Passlock™ detection circuit 1836.
When turning the ignition switch to the start position with the proper key, the Passlock™ sensor generates an analog voltage signal. This signal is sent through the Passlock™ detecting circuit. This analog voltage signal is of a specific value to the vehicle, and varies from vehicle to vehicle. When attempting to start the engine, the BCM compares a preset stored analog voltage value with the signal coming from the sensor. Because both values match, the BCM sends a fuel enable password via the Class 2 serial data link to the powertrain control module (PCM). As a result, the PCM enables the crank relay, and allows fuel delivery to the engine.
When attempting to start the engine by means other than using the proper key in the ignition switch, the Passlock™ sensor sends an analog voltage signal of a different value. The BCM compares the preset stored analog voltage value with the signal coming from the sensor. Because both values do not match, the BCM sends a fuel disable password via the Class 2 serial data link to the powertrain control module (PCM). As a result, the PCM disables the crank relay, and stops fuel delivery to the engine.
Conditions for Setting the DTC
| • | The BCM detects an open or a short to B+ in circuit 1836. |
| • | Condition must be present for one second anytime after the engine has started. |
Action Taken When the DTC Sets
| • | The BCM stores DTC B2958 in the BCM memory. |
| • | The BCM sends a message to the instrument cluster to turn ON the SECURITY indicator. |
| • | The BCM enters fail-enable mode. Upon subsequent engine start attempts, the BCM will send a message to the PCM via Class 2 serial data link to enable the crank relay, and to deliver fuel to the engine. The engine will start. |
Conditions for Clearing the DTC
| • | A current DTC B2958 clears when the BCM detects a valid Passlock™ sensor analog voltage signal on the Passlock™ detection circuit 1836. |
| • | A history DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present. |
| • | Using a scan tool. |
Diagnostic Aids
| • | The following conditions may cause an intermittent malfunction to occur: |
| - | An intermittent open or short to B+ in circuit 1836. |
| - | An intermittent open in circuit 1835 or 1459. |
| - | Poor connections at the BCM or the Passlock™ sensor electrical connector. |
| - | A faulty Passlock™ sensor. |
| • | Check for poor connections at both the BCM and the ignition lock cylinder assembly, these could cause an open, incorrect Passlock™ sensor voltage signal, or intermittent malfunction. If the DTC is a history DTC, the problem may be intermittent. Try performing the tests shown while moving wiring, connectors, and the key, this can often cause the malfunction to appear. |
| • | Perform the diagnostic table for this DTC when the vehicle experiences an engine no crank condition, with the SECURITY indicator ON steadily (after bulb check), and no BCM DTCs stored. This condition may be related due to an open or short to B+ in circuit 1836. The BCM monitors for an open or short to B+ in circuit 1836 causing to set this DTC only AFTER the BCM sampled a valid analog voltage signal from the Passlock™ sensor. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Checks for DTCs indicating a circuit malfunction between the Passlock™ sensor and the BCM.
-
Checks for a faulty BCM not sending power to the Passlock™ sensor.
-
Checks for a faulty BCM or connector not grounding the Passlock™ sensor.
-
Checks for a faulty Passlock™ sensor.
-
Checks for a faulty BCM.
-
Checks for an open in circuit 1459.
-
Checks for an open in circuit 1835.
-
Determines whether there is an open or short to B+ in circuit 1836, or the Passlock™ sensor is faulty.
-
Checks for either an open or short to B+ in circuit 1836.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Theft Deterrent Diagnostic System Check? | |||
Using scan tool, check for BCM current DTCs B2947 and B2960. Are any of these DTCs listed above set as current DTCs in the BCM? | -- | |||
Is the voltage measured within the specified range? | B+ | |||
Using a DMM, measure the resistance by backprobing between the BCM connector C1 terminal B4 and the BCM harness connector C4 terminal B. Is the resistance measured less than the specified value? | 5 ohms | |||
Is the voltage measured less than the specified value? | 4.5 V | |||
Does this DTC reset as a current DTC? | -- | |||
Is the voltage measured within the specified range? | B+ | |||
Using a DMM, measure the resistance between the Passlock™ sensor harness connector terminal B and the BCM harness connector C4 terminal B. Is the resistance measured less than the specified value? | 5 ohms | |||
Using a DMM, measure the voltage between the Passlock™ sensor harness connector terminal A and ground. Is the voltage measured within the specified range? | 4.5-5.5 V | |||
From Step 9, was the voltage measured B+? | -- | |||
11 |
Is the repair complete? | -- | -- | |
12 | Malfunction is intermittent and not present at this time. Refer to Diagnostic Aids for more information. Is the action complete? | -- | -- | |
13 | Repair poor connection or open in circuit 1459. Is the repair complete? | -- | ||
14 | Repair poor connection or open in circuit 1835. Is the repair complete? | -- | -- | |
15 |
Is the repair complete? | -- | -- | |
16 | Repair short to B+ in circuit 1836. Is the repair complete? | -- | -- | |
17 | Repair poor connection or open in circuit 1836. Is the repair complete? | -- | -- | |
18 |
Are there any current BCM DTCs present? | -- | System OK |
