GM Service Manual Online
For 1990-2009 cars only

Object Number: 281486  Size: MF
Theft Deterrent System Components
Cell 133: Fuel Tank Module, Instrument Cluster and Passlock Cylinder
Handling ESD Sensitive Parts Notice

Circuit Description

This circuit supplies the Passlock™ data to the body control module (BCM) from the Passlock™ sensor, CKT 1836.

Conditions for Setting the DTC

All of the following conditions must be met:

    • The Passlock™ option is enabled.
    • Ignition 0 is active.
    • The Passlock™ code data is shorted to ground for 1 second at any time during an ignition cycle.

Action Taken When the DTC Sets

    • The BCM stores the DTC B2957 in the BCM memory.
    • The vehicle will not start.
    • The vehicle will not start or the vehicle will start but the security indicator remains illuminated.

Conditions for Clearing the DTC

    • The BCM goes to sleep and reinitializes with the fault cleared.
    • All of the BCM history codes will be cleared after 100 ignition cycles (from OFF to RUN) with no current codes active during the 100 ignition cycles.
    • A Scan Tool is used.

Diagnostic Aids

    • When the diagnostics direct you to take electrical measurements at the wiring harness junction blocks, refer to Power Distribution Schematics for terminal assignments of the wiring harness junction blocks.
    • If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while wiggling the wiring and connectors. This action often causes the malfunction to appear.

Test Description

The numbers below refer to the numbers on the diagnostic table.

  1. This step determines if a short to ground exists in CKT 1836 between the BCM and the Passlock® sensor.

Step

Action

Value(s)

Yes

No

Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.

1

Was the Theft Deterrent Diagnostic System Check performed?

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Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2

  1. Disconnect the body control module (BCM) connector C2.
  2. Disconnect the Passlock® sensor connector terminal A.
  3. Use the J 39200 in order to measure the resistance in CKT 1836 between the Passlock® connector terminal A and ground.

Is the measured resistance within the specified range?

Go to Step 4

Go to Step 3

3

Repair the short to ground in CKT 1836 between the Passlock® connector terminal A and the BCM connector C2 terminal B6. Refer to Wiring Repairs in Wiring Systems

Is the repair complete?

--

Go to Step 10

--

4

Inspect for a poor connection at the BCM connector C2 terminal B2.

Was a poor connection found?

--

Go to Step 5

Go to Step 6

5

Repair the poor connection at the BCM connector C2 terminal B6. Refer to Wiring Repairs in Wiring Systems

Is the repair complete?

--

Go to Step 10

6

Inspect for a poor connection at the Passlock® sensor connector terminal A.

Was a poor connection found?

--

Go to Step 7

Go to Step 8

7

Repair the poor connection at the Passlock® sensor connector terminal A. Refer to Wiring Repairs in Wiring Systems

Is the repair complete?

--

Go to Step 10

--

8

  1. Replace the Passlock® sensor.
  2. Reconnect the BCM. Refer to the following procedures:
  3. •  Body Control Module Replacement in Body Control Systems
  4. Perform the Reprogramming Procedure Auto Learn.

Is the repair complete?

--

Go to Step 10

Go to Step 9

9

Replace the BCM. Refer to the following procedures:

    •  Body Control Module (BCM) Programming/RPO Configuration in Body Control Systems
    •  Body Control Module Replacement in Body Control Systems

Is the repair complete?

--

Go to Step 10

--

10

Clear the DTCs from the memory.

Are the DTCs cleared from the memory?

--

Go to Diagnostic System Check - Theft Deterrent

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