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

3: Tests for other PASS-Key® DTCs stored in the BCM that will cause a DTC B2721 to set. These DTCs must be diagnosed first.
4: Tests for an intermittent or incorrect PASS-Key® Resister reading due to an incorrect or malfunctioning ignition key.

DTC B2721

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	Install a scan tool. Turn ON the ignition with the engine OFF. Select the Display DTCs function for the BCM. Does the scan tool display DTC B2721 as a current DTC?	Go to Step 3	Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
3	Does the scan tool display DTC B2722 or B2723 as a current DTC?	Go to Diagnostic Trouble Code (DTC) List	Go to Step 4
4	Inspect the ignition key for dirt or obvious damage. Does the ignition key appear dirty or damaged?	Go to Step 11	Go to Step 5
5	Turn OFF the ignition. Disconnect the ignition lock cylinder. 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 . Turn the rotary switch on the J 35628-A to each code number (1-15) and attempt to start the vehicle with each code number. See Special Tools and Equipment . (After each failed starting attempt, you must wait 3 minutes before the next attempt. This step may take as long as 45 minutes due to a trial and error process.) Does the vehicle start with one of the codes selected on the J 35628-A ? See Special Tools and Equipment .	Go to Step 6	Go to Step 7
6	Note the code number on the J 35628-A that successfully started the vehicle. See Special Tools and Equipment . Obtain and cut a new ignition key with the correct key code value. Attempt to start the vehicle with the new ignition key. Does the vehicle start?	Go to Step 13	Go to Step 8
7	Test the following circuits for an open or a short: The key resistor input circuit The key resistor reference ground circuit Did you find and correct the condition?	Go to Step 13	Go to Step 9
8	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 13	Go to Step 11
9	Inspect for poor connections at the harness connector of the body control module. 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 13	Go to Step 12
10	Clean or replace the ignition key as necessary. Refer to Replacing Keys . Did you complete the procedure?	Go to Step 13	-
11	Replace the ignition lock cylinder. Refer to Ignition Switch Lock Cylinder Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement?	Go to Step 13	-
12	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 13	-
13	Use the scan tool in order to clear the DTCs. Attempt to start the vehicle. Does the DTC reset?	Go to Step 2	System OK