For 1990-2009 cars

### Circuit Description

The vehicle theft deterrent system is designed to prevent vehicle theft by disabling the engine unless the lock cylinder is correctly engaged by a mechanical key. The theft deterrent system utilizes four components for theft detection, the lock cylinder, ignition switch, the Body Function Controller (BFC) and the Powertrain Control Module (PCM).

When starting the engine, the PCM looks for a password from the Body Function Controller (BFC) through the Class II serial data circuit. If the password is not recognized or not present, the PCM will disable the engine. There are two modes of tamper detection:

• | No Password Received - Engine will start and stall quickly. THEFT SYSTEM telltale will flash on the IPC.

• | Incorrect or Disable Password Received (More than three invalid passwords are received) The engine is disabled for at least 10 minutes and the THEFT SYSTEM telltale will illuminate solid on the Instrument Panel Cluster (IPC) for the 10 minutes.

After the vehicle has passed theft detection, the PCM will continue normal engine operation. Additional information can be found in Theft Deterrent Systems.

### Conditions for Running the DTC

• | The theft deterrent system has allowed fuel delivery.

• | The PCM is in the theft deterrent password learn mode.

### Conditions for Setting the DTC

The PCM remains in theft deterrent password learn mode for greater than 2 seconds.

### Conditions for Clearing the MIL/DTC

• | A history DTC will clear after 40 consecutive warm up cycles without a fault.

• | DTCs can be cleared by using a scan tool.

### Diagnostic Aids

A new replacement PCM will be in a functional state to learn the password from the BCM. If the BCM is replaced, the PCM must be placed in password learning mode to relearn a new password. Once learned, the password becomes permanent information that remains with the vehicle. The loss of PCM battery or ignition voltage will not affect the programmed password information.

Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems.

Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control Systems for information concerning the password learning procedure.

If the Body Function Controller (BFC) is replaced the PCM must be reflashed to allow the new password to be learned. The ignition must be turned off for at least 30 seconds then on for the PCM to learn the new BFC password.

### Test Description

The numbers below refer to the step numbers 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 fault 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. The theft deterrent password resides in the Body Function controller (BFC). Anytime a VTD component has been replaced, the Powertrain Control Module (PCM) and Body Control Module (BCM) must relearn the new password. The PCM may not have finished learning the new password.

   If the serial data loss occurred after a good theft password has been received, the PCM must be reprogrammed and the password learn and the crankshaft position variation learn procedures must be completed to allow the theft system to operate properly.

4. Replacement PCMs must be programmed. A reprogrammed PCM does not require the password learn procedure to be performed. The password will be learned on the first ignition cycle. The replacement PCM must be reprogrammed and the crankshaft position system variation procedure must be performed.

5. 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 | 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. Perform the Password Learn Procedure in the Password Learn Procedure portion of the service manual.
2. Attempt to restart the engine.

Does the engine start and continue to run?

--

Go to Step 5

Go to Step 3

3 | Was a Vehicle Theft Deterrent (VTD) component recently replaced? | -- | Go to Step 2 | Go to Step 4
4 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 5 | --
5 |

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

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

--

Go to Step 6

Go to Step 2

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