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

The PCM is ready to learn a new Passlock II password after the following items have been completed:

• | The PCM received an incorrect password.

• | The PCM finished the 10 minute learn pending timer, ie. leaving the ignition switch ON for 10 minutes.

### Action Taken When the DTC Sets

• | The PCM will record operating conditions at the time the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.

• | A history DTC stores.

### 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. This DTC is normally set and cleared during a password learn procedure. If the password learn procedure is not completed, this DTC will not be cleared.

3. 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 Crankshaft Position System Variation Learn for the Crankshaft Position Variation Procedure.

4. 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 P1630 - Powertrain is in the Password Learn Mode

Step | Action | Value(s) | 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 if DTC P1630 is an active DTC with the scan tool.

Is DTC P1630 active?

--

Go to Step 3

Go to Step 10

3 | Is DTC P1632 also set? | -- | Go to Step 4 | Go to Step 7
4 | Is DTC U1064 also set? | -- | Go to DTC U1064 Loss of Communications with BCM | Go to Step 5
5 | Check for any Body Control Module (BCM) DTC(s) (related to Theft Deterrent) 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 8
7 |

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

Does the engine start and continue to run?

--

Go to Step 6

Go to Step 8

8 |

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

Was a problem found?

--

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