The body control module (BCM) will read an analog voltage form the Passlock sensor. Based on an internal reference, the BCM will determine if the measured voltage is in 1 of the following conditions:
| • | Open | 
| • | Shorted to ground | 
| • | A valid code | 
| • | A tamper code | 
There are 10 possible valid code combination. The BCM will only recognize the last learned valid code.
| • | The ignition switch is ON. | 
| • | The BCM signal input is less than 0.4 volts for 1 second after turning the ignition switch to the CRANK position. | 
| • | The vehicle will not start if the fault occurs before you start the vehicle. The security telltale will flash for 10 minutes then turn ON steady. | 
| • | If the vehicle is running when the fault occurs, the BCM will be in the fail enable mode allowing the vehicle to start and run. The security telltale will be ON. | 
| • | The DTC will clear once the ignition cycle has occurred without the fault recurring. | 
| • | The BCM history codes will clear once 100 concurrent ignition cycles occur without the fault recurring. | 
| • | Using a scan tool. | 
| • | When replacing the Passlock sensor, all of the following components are included as a replacement part and must be replaced: | 
| - | The lock | 
| - | The sensor | 
| - | The filter | 
| - | The harness | 
| • | Use a scan tool in order to inspect the Passlock data voltage and the Passlock code. | 
| • | Perform a visual inspection of the wiring and the connectors. | 
| • | Following a repair the tamper timer needs 10 minutes in order to expire. | 
The numbers below refer to the step numbers on the diagnostic table.
Tests for proper operation of the circuit in the high voltage range.
Tests for a short to ground in the Passlock™ sensor signal circuit.
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 indicate that the Passlock™ data voltage is within the specified range?  | 0.4-4.9v  | Go to Testing for Intermittent Conditions and Poor Connections  | Go to Step 3  | ||||||||||||||||||||
 Does the scan tool indicate that the Passlock™ data voltage is greater than the specified value?  | 4.9v  | Go to Step 7  | Go to Step 4  | |||||||||||||||||||||
Test the Passlock™ sensor signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?  | --  | Go to Step 10  | Go to Step 5  | |||||||||||||||||||||
5  | Inspect for poor connections at 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 10  | Go to Step 6  | ||||||||||||||||||||
6  | 
 Important: Perform the set up procedure for the body control module . Replace the body control module. Refer to Body Control Module Replacement in Body Control Systems. Did you complete the replacement?  | --  | Go to Step 10  | --  | ||||||||||||||||||||
7  | 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 10  | Go to Step 8  | ||||||||||||||||||||
8  | 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 9  | --  | ||||||||||||||||||||
9  | Perform one of the following Passlock™ learn procedures: 
 
 Is the repair complete?  | --  | Go to Step 10  | --  | ||||||||||||||||||||
10  | 
 Does the DTC reset?  | --  | Go to Step 3  | System OK  |