Circuit Description
The body control module (BCM) produces the theft deterrent fuel enable signal when ignition is ON and the proper key resistor pellet is sensed. The powertrain control module (PCM) monitors the fuel enable signal during crank. If the proper signal is present on the theft deterrent fuel enable circuit, the PCM enables fuel delivery to allow the engine to start. If the PCM detects that the fuel enable signal is not present or incorrect during engine crank, DTC P1629 will be set. DTC P1629 can cause a no-start condition or normal operation depending on when the loss of the fuel enable signal was detected. The engine will continue to start and run if the condition that set DTC P1629 occurred after the BCM sensed the proper key resistor pellet and signaled the PCM to continue fuel delivery. The engine will start and immediately stall if the condition that set DTC P1629 occurred before the BCM sensed the proper key resistor pellet. With this condition present, the PCM will inhibit fuel delivery and the BCM will disable the starter.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
| • | The PCM detects an incorrect signal on the theft deterrent fuel enable circuit. |
| • | The condition is present for more than 2 seconds. |
Action Taken When the DTC Sets
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
Many situations may lead to an intermittent condition. The following list is to be used as a guide to assist in detecting an intermittent:
| • | Loose terminal connection. |
| Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Wiring Systems for diagnosis and repair. |
| • | Damaged harness. |
| Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Systems for diagnosis and repair. |
| • | Inspect the PCM and the engine grounds for clean and secure connections. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Theft Deterrent System Schematics | ||||||||
1 | Did you perform A Diagnostic System Check-Theft Deterrent? | -- | Go to Step 2 | |||||
2 |
Does the scan tool display DTC P1629 as a current DTC? | -- | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | ||||
3 |
Does the voltage measure at or near the specified value? | 5 V | Go to Step 4 | Go to Step 6 | ||||
4 |
Does the tool indicate a valid code (1-15)? | -- | Go to Step 5 | Go to Step 12 | ||||
Does the code received match the code from the previous step? | -- | Go to Step 8 | Go to Step 9 | |||||
6 | Test the vehicle theft deterrent fuel enable circuit for an open, short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 7 | ||||
7 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 10 | ||||
8 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 | ||||
9 | Test the following circuits for an open, high resistance, short to ground or a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 13 | ||||
10 |
Important: When replacing the PCM, perform the programming procedure. Refer to Powertrain Control Module Programming 3.8L or Powertrain Control Module Programming 5.7L in Engine Controls. Replace the PCM. Refer to Powertrain Control Module Replacement 3.8L or Powertrain Control Module Replacement 5.7L in Engine Controls. Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
11 |
Important: When replacing the BCM, perform the relearn procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System. Replace the BCM. Refer to Body Control Module Replacement in Body Control System. Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
12 | Replace the ignition key. Refer to Replacing Keys . Did you complete the repair? | -- | Go to Step 14 | -- | ||||
13 | Replace the ignition lock cylinder. Refer to Ignition Lock Cylinder Replacement - On Vehicle in Steering Wheel and Column-Tilt. Did you complete the repair? | -- | Go to Step 14 | -- | ||||
14 |
Does the vehicle start and run? | -- | System OK | Go to Step 2 | ||||
