Circuit Description
The Passlock system is designed to prevent engine operation if the correct key is not used to start the vehicle. The ignition key turns the lock cylinder, cylinder rotation produces an analog voltage code in the Passlock sensor.
The Passlock/EVO module receives this voltage code and is compared to the last learned voltage code. If the codes match, the Passlock/EVO module sends a class 2 message to the VCM, enabling the fuel injectors.
Diagnostic Aids
You must perform the Diagnsotic System Check prior to diagnosing any symptom or any Diagnostic Trouble Code table. Diagnose the DTCs in the order specified in the Passlock System "Displaying Diagnostic Trouble Codes" List. Failure to do so may result in the following conditions:
| • | Extended diagnostic time |
| • | Incorrect diagnosis |
| • | Incorrect parts replacement |
If a Passlock/EVO module, a passlock sensor, or the VCM have been replaced, perform the learn procedure before following the Diagnostic System Check.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Connect a scan tool to the data link connector. Can the scan tool be powered up? | -- | Go to Step 2 | Go to Step 6 |
2 | Turn the ignition switch to the LOCK position. Is the SECURITY telltale on? | -- | Go to Step 3 | |
3 |
Did the SECURITY telltale turn on? | -- | Go to Step 4 | |
4 | Did the SECURITY telltale turn on and remain on for more than 6 seconds? | -- | Go to Step 7 | Go to Step 5 |
5 | Does the SECURITY telltale flash? | -- | Go to Step 7 | Go to Step 9 |
6 | Refer to Diagnostic System Check - Data Link Communications in Wiring Systems Is the repair complete? | -- | Go to Step 1 | -- |
7 | Using the scan tool, test for current and history Passlock DTC(s). Does the scan tool display "No Communication with Vehicle..."? | -- | Go to Step 8 | |
8 | Is there any current Passlock DTC or a history B2958 DTC present? | -- | ||
9 | Attempt to start the vehicle. Does the engine crank fast enough to start the vehicle? | -- | Go to Step 10 | Go to Step 13 |
10 | Using the scan tool, monitor the "passlock code" from the Passlock Data List. Does the scan tool read "Passlock Code Open"? | -- | Go to Step 11 | |
11 | Does the engine start and run? | -- | System OK | Go to Step 12 |
12 | Refer to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 4.3L. Is the repair complete? | -- | Go to Step 1 | -- |
13 | Refer to Starting System Check in Engine Electrical. Is the repair complete? | -- | Go to Step 1 | -- |
