Circuit Description
When the ignition switch is turned to ON position, the ignition key is tested by the theft deterrent system. While the ignition key code is read by the theft deterrent control module, the engine can start to run for 2 seconds with any key that will turn the lock cylinder. The key code is read and compared with key codes that have been stored in the memory of the theft deterrent control module. If a valid key is detected, the theft deterrent control module sends a serial data release message to the engine control module (ECM) which will allow the engine to continue to run. Included in the release message is an identification (ID) code which assures that neither the theft deterrent control module or the ECM have been substituted to defeat the system. If the ECM receives an invalid release message or can not communicate with the theft deterrent control module, it will disable the fuel system.
If the ECM receives an invalid release message from the theft deterrent control module, this DTC sets.
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC P1629 Theft Deterrent Fuel Enable Signal Not Correct
Conditions for Running the DTC
| • | The ignition is ON or the engine is cranking. |
| • | The DTC P1629 diagnostic runs once per ignition cycle. |
Conditions for Setting the DTC
The ECM receives an invalid release message from the theft deterrent control module.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM will store conditions which were present when the DTC was set as Failure Records data only. |
| • | This information will not be stored in the Freeze Frame data. |
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 the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Diagnostic Aids
An invalid release message from the theft deterrent control module could be caused by the following:
| • | An open or a short in the key signal and low reference circuits of the reader/exciter of the theft deterrent system. The key signal and low reference circuits of the reader/exciter will also cause the security indicator of the theft deterrent system to be ON in a steady state with the ignition in the ON position. |
| • | A malfunctioning reader/exciter of the theft deterrent system. |
| • | An ignition key concern will also cause the security indicator of the theft deterrent system to be ON in a flashing state with the ignition in the ON position. Inspect for the following: |
| - | Not programmed - Refer to Programming Theft Deterrent System Componentsin Theft Deterrent. |
| - | A faulty transponder |
| • | Wrong or improperly programmed theft deterrent control module. Refer to Programming Theft Deterrent System Components in Theft Deterrent. |
| • | An intermittent electrical condition in the theft deterrent system can cause this code to set. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Theft Deterrent System Schematics in Theft Deterrent Connector End View Reference: Theft Deterrent System Connector End Viewsin Theft Deterrent | ||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||
2 |
Does the engine start and idle? | -- | Go to Diagnostic Aids | Go to Step 3 | ||||
3 |
Is the security indicator flashing? | -- | Go to Step 5 | Go to Step 4 | ||||
4 |
Is the resistance within the specified range? | 4.5-5.3 ohms | Go to Step 7 | Go to Step 6 | ||||
5 | Test the ignition key for one of the following conditions:
Did you find and correct the condition? | -- | Go to Step 10 | Go to Diagnostic System Check - Theft Deterrentin Theft Deterrent | ||||
6 | Test for an intermittent and for a poor connection at the reader/exciter. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct a condition? | -- | Go to Step 10 | Go to Step 8 | ||||
7 | Test for an intermittent and for a poor connection at the theft deterrent control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairsin Wiring Systems. Did you find and correct a condition? | -- | Go to Step 10 | Go to Step 9 | ||||
8 | Replace the reader/exciter. Refer to Theft Deterrent Module Replacement in Theft Deterrent. Did you complete the replacement? | -- | Go to Step 10 | -- | ||||
9 | Replace the theft deterrent control module. Refer to Theft Deterrent Module Replacement in Theft Deterrent. Did you complete the replacement? | -- | Go to Step 10 | -- | ||||
10 |
Did the engine start and run with no DTC P1629 set? | -- | System OK | Go to Step 2 | ||||
