GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Safari - 2WD 🢒 Body and Accessories 🢒 Theft Deterrent 🢒 Engine Cranks But Does Not Start

Object Number: 381483 Size: LF
Theft Deterrent System Components
Theft Deterrent System Schematics
Theft Deterrent System Schematic Icons
Theft Deterrent System Schematic Icons

Circuit Description

The Passlock module will read an analog voltage from the Passlock sensor. Based on an internal reference the Passlock module will determine if the measured voltage is open, shorted to ground, a valid code, or a tamper code. There are 10 possible valid code combinations. The Passlock module will only accept the last learned valid code.

Diagnostic Aids
    • Prior to cranking, if a problem developed to prevent the Passlock sensor signal from reporting to the Passlock module, the vehicle will not start and DTC B2958 will not be set. In this case, the scan tool will still read "Passlock Code Open" after cranking.
    • When replacing the Passlock sensor, all the sensor components; the lock, the sensor, the filter, and the harness, are included as a replacement part and must be replaced.
    • Use the scan tool in order to test the Passlock data voltage and the Passlock code.
    • Perform a visual inspection of the wiring and the connectors.
    • Inspect the Passlock sensor harness for an intermittent or poor connections (including the in-line connector). Refer to Intermittents and Poor Connections .

Test Description

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

  1. This step determines if the Passlock data terminal has an open condition or a short to battery.

    2.

  2. This step determines if the Passlock sensor power is available at the Passlock module. If CKT 812 is shorted to ground, DTC B2947 will set. Diagnosing and repairing DTC B2947 may eliminate the engine cranking but not starting condition.

    3.

  3. This step tests the Passlock sensor ground.

    4.

  4. This step tests for an open in any of the Passlock sensor line.

    5.

  5. This step tests for a short to battery on the Passlock sensor signal line.

    6.

  6. This step isolates the problem between the Passlock sensor and CKT 1836.

Step

Action

Value(s)

Yes

No

1

Did you perform the VTD Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - Theft Deterrent

2
  1. Set the parking brake.
  2. Rotate the ignition switch from OFF to crank to the ON position.
  3. Use a J 39200 digital multimeter (DMM) in order to measure the voltage from the Passlock module connector terminal B7 to ground.

Is the voltage within the specified range?

4.9-5.0 V

Go to Step 3

Go to Step 7

3

Use a J 39200 DMM in order to measure the voltage from the Passlock module connector terminal A5 to ground.

Is the voltage within the specified range?

9-16 V

Go to Step 4

Go to DTC B2947 Security System Sensor Power CKT Low

4

Use a J 39200 DMM in order to measure the voltage between the Passlock module connector terminal A5 and terminal B5.

Is the voltage within the specified range?

9-16 V

Go to Step 5

Go to Step 8

5
  1. Turn the ignition switch OFF.
  2. Disconnect the Passlock module connector.Refer to Theft Deterrent Module Replacement .
  3. Disconnect connector C201 at the base of the steering column.
  4. Use a J 39200 DMM in order to test for resistance between the following connectors:
    5. • Connector C201 terminal B1 and the Passlock module connector terminal A5
    • Connector C201 terminal D3 and the Passlock module connector terminal B7
    • Connector C201 terminal C4 and the Passlock module connector terminal B5

Is the resistance within the specified range on all 3 circuits?

0-5ohms

Go to Step 6

Go to Step 11

6
  1. Insure the Passlock sensor composite tip (3/10x4/10 inch) is mounted flush in the center of the lock cylinder housing closest to the steering wheel.
  2. Insure the magnet at the center of the lock cylinder outer edge (1/10 x 3/10) inch is tightly fitted and supported by a composite piece on the side.
  3. Insure that lock cylinder magnet is not demagnetized and is capable of pulling a pocket screw driver placed on a bench from a minimum distance of 1/10 inch, if not replace ignition lock cylinder (and magnet) assembly. Refer to Ignition Lock Cylinder Replacement - On Vehicle in Steering Wheel and Column.

If all the above are OK, Replace the Passlock sensor in the electronic column lock module assembly.

    • With Tilt Wheel
       - To disassemble the lock module assembly, refer to Electronic Column Lock Module - Disassemble - Off Vehicle in Steering Wheel and Column - Tilt.
       - To assemble the lock module assembly, refer to Electronic Column Lock Module - Assemble - Off Vehicle in Steering Wheel and Column - Tilt.
    • With Standard Wheel
       - To disassemble the lock module assembly, refer to Electronic Column Lock Module - Disassemble - Off Vehicle in Steering Wheel and Column - Standard.
       - To assemble the lock module assembly, refer to Electronic Column Lock Module - Assemble - Off Vehicle in Steering Wheel and Column - Standard.

Is the repair complete?

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Go to Step 12

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7
  1. Turn the ignition switch OFF.
  2. Disconnect the Passlock module connector. Refer to Theft Deterrent Module Replacement .
  3. Turn the ignition switch ON.
  4. Use a J 39200 DMM in order to test for voltage from the Passlock/EVO module connector terminal B7 to ground.

Is the voltage above the specified value?

1.0 volt

Go to Step 9

Go to Step 8

8
  1. Turn the ignition switch OFF.
  2. Replace the Passlock module. Refer to Theft Deterrent Module Replacement .

Is the repair complete?

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Go to Step 12

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9
  1. Disconnect the C201 connector at the base of the steering column.
  2. Use a J 39200 in order to test for voltage from the Passlock module connector terminal B7 to ground.

Is the voltage above the specified value?

1.0 volt

Go to Step 10

Go to Step 06

10

Repair the short to battery in CKT 1836.

Is the repair complete?

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Go to Diagnostic System Check - Theft Deterrent

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11

Repair the open in the appropriate circuit from the following list:

    • CKT 812
    • CKT 1836
    • CKT 1057

Is the repair complete?

--

Go to Diagnostic System Check - Theft Deterrent

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12
  1. Reconnect all the previously disconnected connectors and the components.
  2. Turn the ignition switch ON.
  3. Connect the scan tool.
  4. Clear the DTCs.
  5. Perform one of the following Passlock reprogramming procedures:

Is the repair complete?

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Go to Diagnostic System Check - Theft Deterrent

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