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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 744 (THEFT DETERRENT SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC B2723TEST DESCRIPTION
1999 GMC Forward Control 5.7 R, Automatic

Test Description

1999 GMC Forward Control 5.7 R, AutomaticSECTION Test Description
WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 4:  This test verifies the integrity of the key resistor circuits between the ignition switch and the BCM.
DTC B2723

Step Action Yes No
Schematic Reference:  Theft Deterrent System Schematics  
Connector End View Reference:  Theft Deterrent System Connector End Views  
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 ignition OFF.
  3. Select the BCM Display DTCs function on the scan tool.
Does the scan tool display B2723 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 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. See Special Tools and Equipment .
  5. Turn the rotary switch on the J 35628-A  to the same code number as the ignition key. See Special Tools and Equipment .
  6. Attempt to start the vehicle.
Does the vehicle start?		 Go to Step 7  Go to Step 5 
5 Test the following circuits for an open or a short to voltage:
  • The key resistor input circuit
  • The key resistor reference ground circuit

Did you find and correct the condition?		 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 switch lock cylinder. Refer to Ignition Switch Lock Cylinder Replacement in Instrument Panel, Gages and Console.
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. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 Go to Step 2  System OK
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.