The body control module (BCM) will read an analog voltage from the Passlock™ sensor. Based on the Passlock™ internal reference, the BCM will determine if the indicated voltage is one of the following conditions:
| • | Open | 
| • | Shorted to ground | 
| • | A valid code | 
| • | A tamper code | 
In the case of a tamper condition, the BCM will be reading a tamper code.
| • | The BCM will inspect for a tamper code when the ignition switch rotates from ON to CRANK and will continue to monitor the signal during the engine running period. | 
| • | The BCM is reading a tamper code from the Passlock™ sensor for longer than 1.0 seconds. | 
| • | The vehicle will not run. The security telltale will be flashing. | 
| • | The Passlock™ state is Tamper. | 
| • | The DTC will clear once an ignition cycle occurs without the fault recurring. | 
| • | The BCM history codes will clear after 100 ignition cycles occur without the fault recurring. | 
| • | Use a scan tool. | 
| • | Prior to replacing a BCM, ensure that all of the diagnostics have been completed. Refer to Diagnostic Trouble Code (DTC) List/Type . | 
| • | Inspect the Passlock™ sensor harness for intermittent or poor connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. | 
| • | The VTD internal diagnostics are not run while the tamper timer is active. | 
The numbers below refer to the step numbers on the diagnostic table:
Step  | Action  | Value(s)  | Yes  | No  | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1  | Did you perform the Theft Deterrent (VTD) Diagnostic System Check?  | --  | Go to Step 2  | |||||||||||||||||||||||||
2  | 
 Does the scan tool display DTC B3033 as a current DTC?  | --  | Go to Step 3  | Go to Testing for Intermittent Conditions and Poor Connections  | ||||||||||||||||||||||||
Inspect the area around the ignition lock cylinder for any device which could create a magnetic field (audio speaker, magnet, etc...) Is there a magnetic device near the ignition lock cylinder?  | --  | Go to Step 4  | Go to Step 5  | |||||||||||||||||||||||||
4  | Remove the device creating the magnetic force. Did you complete the repair?  | --  | Go to Step 8  | --  | ||||||||||||||||||||||||
5  | Inspect for poor connections at the Passlock ™ sensor. 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 8  | Go to Step 6  | ||||||||||||||||||||||||
6  | Replace the Passlock™ sensor in the electronic column lock module assembly. Use the appropriate procedure from the following list: 
 
 
 
 
 
 
 
 
 
 
 
 Did you complete the replacement?  | --  | Go to Step 7  | --  | ||||||||||||||||||||||||
7  | Perform one of the following Passlock™ learn procedures: 
 
 Is the repair complete?  | --  | Go to Step 8  | --  | ||||||||||||||||||||||||
8  | You may have to wait up to 10 minutes in order to reset the BCM and synchronize all of the Passlock™ components. 
 Does the DTC reset?  | --  | Go to Step 3  | System OK  |