Refer to Engine Controls Schematics .
Circuit Description
A Class II serial data communications system is used on this vehicle to allow various modules to communicate and share information with each other. Each bit of information has one of 2 lengths: long or short. This allows vehicle wiring to be reduced and the transmission and reception of multiple signals over a single wire. The messages carried on a Class II serial data streams are also prioritized. If 2 messages attempt to establish communications on the data line at the same time, the message with the higher priority will continue. The message with the lower priority message will wait. If a module cannot respond to the Powertrain Control Module (PCM), a DTC is stored.
Conditions for Running the DTC
DTC 1631 is not present and an attempt is made to start the engine.
Conditions for Setting the DTC
The PCM detects an incorrect signal on the Theft Deterrent Fuel Enable Circuit.
The above conditions are present for longer then 2 seconds.
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Diagnostic Aids
For complete serial data line schematics and VTD system diagnosis, refer to Wiring Systems.
An intermittent may be caused by a faulty connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect for the following conditions:
Important: Several body function controller (BFC) diagnostic procedures call for disconnecting the BFC and then turning the vehicle ignition switch to the RUN position. These procedures will result in the PCM setting DTC P1626. Therefore, DTC P1626 stored in history may be the result of previous BFC diagnostic work.
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | 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 Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in 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 Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Important: : If a loss of DLC data has already been diagnosed using the DLC diagnosis table, clear this DTC and continue diagnosis with Powertrain On Board Diagnostic (OBD) System Check . Important: : If body control module (BCM) diagnostic procedures have been performed, clear this DTC and continue diagnosis with Powertrain On Board Diagnostic (OBD) System Check . Attempt to select vehicle theft deterrent system data with the scan tool. Can the vehicle theft deterrent system data be displayed? | -- | ||
3 |
Did you complete the repair? | -- | ||
4 |
Did you complete the repair? | -- | Go to Diagnostic Aids | |
5 |
Did you complete the repair? | -- | Go to Diagnostic System Check - Theft Deterrent in Theft Deterrent. | |
6 |
Does the vehicle start and continue to run? | -- | System OK |
