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Home >> Buick >> 2004 >> Century Base >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Anti-Theft Systems >> Theft Deterrent System >> Diagnostic Information and Procedures >> DTC B2957: Security System Sensor Data Circuit Low >> Test Description

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. 4:  This test verifies the integrity of the key resistor circuits between the ignition switch and the BCM.
DTC B2957

Step Action Yes No
Schematic Reference: Theft Deterrent System Schematics 
1 Did you perform the Theft Deterrent Diagnostic System Check? Go to Step 2  Go to Diagnostic System Check - Theft Deterrent 
2
  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.
  3. Select the BCM Display DTCs function on the scan tool.
Does the scan tool display B2957 as a current DTC?		 Go to Step 3  Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
3 Inspect the ignition key for dirt or obvious damage.
Does the ignition key appear dirty or damaged?		 Go to Step 8  Go to Step 4 
4 
  1. Turn off the ignition.
  2. Disconnect the ignition lock cylinder connector.
  3. Connect a J 35628-A  Vats/Passkey Interrogator using terminal adapters from a. See Special Tools and Equipment . J 35616  to the key resistor input circuit and key resistor reference ground circuit. See Special Tools and Equipment .
  4. Insert the ignition key into the key code reader on the J 35628-A and note the code on the LCD display.
  5. Turn the rotary switch on the J 35628-A to the same code number as the ignition key.
  6. Attempt to start the vehicle.
Does the vehicle start?		 Go to Step 7  Go to Step 5 
5 Test the following circuits for a short to ground:
  • The key resistor input circuit
  • The key resistor reference ground circuit

Was a condition found and corrected?		 Go to Step 11  Go to Step 6 
6 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 11  Go to Step 10 
7 Inspect for poor connections at the harness connector of the ignition lock cylinder. 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 11  Go to Step 9 
8 Clean or replace the ignition key as necessary. Refer to Replacing Keys .
Did you complete the procedure?		 Go to Step 11  -
9 Replace the ignition lock cylinder. Refer to Ignition Lock Cylinder Replacement in Steering Wheel and Column.
Did you complete the replacement?		 Go to Step 11  -
10
IMPORTANT: When replacing the BCM, perform the relearn procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.
Replace the BCM. Refer to Body Control Module Replacement in Body Control System.Did you complete the repair?		 Go to Step 11  -
11
  1. Use the scan tool in order to clear the DTCs.
  2. Attempt to start the vehicle.
Does the DTC reset?		 Go to Step 2  System OK
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