For 1990-2009 cars
Data Link Communications Components
Data Link Connector Schematics
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### 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 four following components for theft detection:

• | Lock cylinder

• | Ignition switch

• | Body control module (BCM)

• | Powertrain Control Module (PCM)

When the ignition switch is first turned ON, the body control module (BCM) will send a password to the PCM through the class 2 serial data circuit. If the BCMs 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 not start at all.

The SYSTEM telltale will flash on the 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 that the SYSTEM telltale will flash on the IPC for approximately 4 seconds then illuminate solid on the instrument panel cluster (IPC) for the 10 minutes for the following passwords received:

• | Fuel disabled

• | Undecided

• | Mismatched

The following are four situations in which the PCM and BCM passwords would not match:

• | PCM does not receive a password from the BCM (No communication between the BCM and PCM)

• | BCM sends a Fuel Disabled password, meaning a tamper has occurred.

• | BCM sends an Undecided password.

• | PCM receives a password (more than three invalid passwords are received other than Fuel Disabled or Undecided) from the BCM that does not match (swapped PCM or BCM).

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 the Theft Deterrent section.

### Conditions for Setting the DTC

• | Received a fuel disabled password from the body control module (BCM).

• | Received an undecided password was sent from the body control module (BCM).

• | Received no password sent from the body control module (BCM).

• | Received a password from the body control module (BCM) which did not match the PCM password.

### Action Taken When the DTC Sets

• | The PCM will record 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

• | Engine fueling is disabled by the body control module (BCM).

• | The fuel system is disabled by the PCM.

### Conditions for Clearing the MIL/DTC

• | As soon as one good (matching) passwords are 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.

• | A scan tool can 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:

• | Poor electrical terminal connection

• | Broken wire inside the insulation

Thoroughly check any suspected circuitry for the following items:

• | Backed out terminals or improper mating

• | Improperly formed or damaged terminals

• | Poor terminal to wiring connections

• | Physical damage to the wiring harness

• | Corrosion

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool for later reference.

2. The scan tool can display whether or not the Body Control Module (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 due to a password that has not yet been learned due to a component being replaced, or a problem in the BCM or a VTD component.

3. A Passlock theft deterrent DTC being set indicates that a Passlock II component may be malfunctioning.

4. The PCM may not have learned the new password. Refer to the Password Learn .

5. Replacement PCMs must be reprogrammed. A reprogrammed PCM does not require the password learn procedure to be performed. The password will be learned on the first ignition cycle. Refer to the latest Techline information for programming procedures. The replacement PCM must be reprogrammed and the crankshaft position system variation procedure must be performed. Refer to the latest Techline procedures for PCM reprogramming and the Crankshaft Position System Variation Learn portion of the service manual for the Crankshaft Position Variation Procedure.

6. If no malfunctions have been found at this point and no additional DTCs were set, refer to Diagnostic Aids for additional checks and information.

#### DTC P1632 - Fuel Disabled Due to Vehicle Theft Deterrent (VTD)

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn ON the ignition switch leaving the engine OFF.
2. Install a scan tool.
3. Check for DTC U1064 with the scan tool.

Is DTC U1064 also set?

--

Go to DTC U1064 Loss of Communications with BCM

Go to Step 3

3 | Is DTC P1630 and P1632 set together? | -- | Go to DTC P1630 Theft Deterrent Learn Mode Active | Go to Step 4
4 | Is DTC P1631 and P1632 set together? | -- | Go to DTC P1631 Theft Deterrent Start Enable Signal Not Correct | Go to Step 5
5 | Check the Body Control Module (BCM) for any DTC(s) with the scan tool. Were any BCM DTC(s) set? | -- | Go to Body Control Module System Check | Go to Step 6
6 | Check for any Passlock Theft Deterrent DTC(s) with the scan tool. Were any Passlock Theft Deterrent DTC(s) set? | -- | Go to Diagnostic System Check - Theft Deterrent | Go to Step 7
7 |

1. Perform the Body Control Module (BCM) Diagnostic System Check. Refer to Body Control Module System Check .
2. Repair any problem found.

Was a problem found?

--

Go to Step 8

Go to Step 9

8 |

1. Perform the Password Learn Procedure. Refer to the Password Learn .
2. Attempt to restart the engine.

Does the engine start and continue to run?

--

Go to Step 10

Go to Step 9

9 |

1. Turn OFF the ignition switch.
2. Replace the PCM. Refer to the Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 10

--

10 |

1. Using the scan tool, clear DTCs.
2. Start the engine.
3. Idle the engine at normal operating temperature.
4. Operate the vehicle within the conditions for running this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?

--

Go to Step 11

Go to Step 2

11 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK