2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2439
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC P1631
- Theft Deterrent Fuel Enable Signal Not Correct
Circuit/System Description
The theft deterrent module (TDM) sends the prerelease password to the engine control module (ECM) via the serial data circuit. The ECM then
sends a challenge to the TDM. Both the ECM and TDM perform a calculation on this challenge. If the calculated response from the TDM equals
the calculation performed by the ECM, the ECM will allow vehicle starting.
Conditions for Running the DTC
Ignition is in the ACCESSORY or RUN position.
Conditions for Setting the DTC
The ECM receives an incorrect prerelease password from the TDM.
Action Taken When the DTC Sets
* The security indicator will illuminate.
* Vehicle starting will be disabled.
Conditions for Clearing the DTC
* A current DTC P1631 will be when a correct fuel enable password is received.
* A history DTC will be cleared after 40 malfunction-free ignition cycles or when a scan tool is used to clear DTCs.
Reference Information
Schematic Reference
Immobilizer Schematics (See: Accessories and Optional Equipment/Antitheft and Alarm Systems/Diagrams/Electrical Diagrams/Immobilizer
Schematics)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Immobilizer Description and Operation (See: Accessories and Optional Equipment/Antitheft and Alarm Systems/Description and
Operation/Immobilizer Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
Important: Because of normal system communications between the TDM and ECM, any theft deterrent B-codes must be diagnosed prior
to the diagnosis of P-codes.
Perform the 10-Minute Immobilizer Relearn procedure. Refer to Immobilizer System Component Programming (See: Accessories and Optional
