Refer to
Power, Ground, CPP, AT, and Cruise Control Brake Switch
in Engine Controls
Schematics.
Circuit Description
The vehicle theft deterrent (VTD) system, called a Passlock II system, is designed to prevent vehicle theft by disabling the engine unless the Passlock lock cylinder is correctly engaged by a mechanical key. The Passlock II System utilizes the following components for theft detection:
| • | The lock cylinder |
| • | The ignition switch |
| • | The body control module (BCM) |
| • | The powertrain control module (PCM) |
When the ignition switch is first turned on, the BCM will send a password to the PCM through the Class 2 serial data circuit. If the BCM password does not match the password that is stored in the PCM, the PCM will disable the engine. This will cause the engine to start and stall immediately, or to not start.
The SYSTEM telltale will flash on the instrument panel cluster (IPC) and the engine is disabled until a matching password is received. The password is checked every 4 seconds. The engine is disabled for at least 10 minutes and the SYSTEM telltale will flash for approximately 4 seconds then illuminate steady for the 10 minutes if the following passwords are received:
| • | Fuel disabled |
| • | Undecided |
| • | Mismatched |
The following are situations in which the PCM and BCM passwords would not match:
| • | The PCM does not receive a password from the BCM. |
| • | The BCM sends a Fuel Disabled password, meaning a tamper has occurred. |
| • | The BCM sends a Undecided password. |
| • | The PCM receives a password from the BCM that does not match. |
After the vehicle has passed theft detection, the PCM will continue a normal engine operation. If the PCM loses the BCM communication within the same ignition cycle, the vehicle will continue to run on the following ignition cycles. This mode is called the Fail Enable mode. Additional information can be found in Theft Deterrent.
Conditions for Setting the DTC
| • | The PCM receives a fuel disabled password from the BCM. |
| • | The PCM receives an undecided password from the BCM. |
| • | The PCM does not receive a password from the BCM. |
| • | The PCM receives a password from the BCM which does not match the PCM password |
Action Taken When the DTC Sets
| • | The PCM will record the operating conditions at the time during which the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
| • | A history DTC stores. |
| • | The fuel system is disabled by the PCM. |
Conditions for Clearing the MIL/DTC
| • | As soon as a matching password is received at key-up (anything but a Fuel Disabled and Undecided password) this becomes a history code |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
Attempting to start the vehicle by bypassing the Passlock ll system or by substituting parts without performing the password learn procedure may set a DTC P1631 and a P1632.
If no password is received, a DTC U1064 and P1632 may be set.
An intermittent may be caused by the following conditions:
| • | A faulty electrical terminal connection |
| • | A broken wire inside the insulation |
Thoroughly inspect any suspected circuitry for the following items:
| • | Backed-out terminals or improper mating |
| • | Improperly formed or damaged terminals |
| • | Faulty terminal-to-wire connections |
| • | Physical damage to the wiring harness |
| • | Corrosion |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
The scan tool can display whether or not the BCM has received and learned the password from the lock cylinder. If the password is not received, the reason the PCM set this DTC may be due to a password that has not yet been learned after a component is replaced, or a problem in the BCM or a VTD component.
-
A Passlock theft deterrent DTC set indicates that a Passlock II component may be malfunctioning.
-
The replacement PCM must be programmed and the Crankshaft Position System Variation Learn procedure must be performed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
2 | Use a scan tool in order to determine if DTC U1064 is set. Is DTC U1064 set? | -- | Go to DTC U1001-U1254 Loss of XXX Communications in Data Link Communications | Go to Step 3 |
3 | Are DTC P1630 and DTC P1632 set together? | -- | Go to Step 4 | |
Are DTC P1631 and DTC P1632 set together? | -- | Go to DTC P1631 Theft Deterrent Start Enable Signal Not Correct | Go to Step 5 | |
5 | Use a scan tool in order to determine if any BCM DTCs set. Are any BCM DTCs set? | -- | Go to Diagnostic System Check - Body Control System in Body Control System | Go to Step 6 |
Use a scan tool in order to determine if any Passlock theft deterrent DTCs set. Are any Passlock theft deterrent DTCs set? | -- | Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent | Go to Step 7 | |
7 |
Did you find and correct the condition? | -- | Go to Step 8 | Go to Step 9 |
8 |
Does the engine start and continue to run? | -- | Go to Step 10 | Go to Step 9 |
|
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the repair? | -- | Go to Step 10 | -- | |
10 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
