2010 Cadillac Truck SRX FWD V6-3.0L Page 1888
Circuit/System Description
The engine control module (ECM) controls the throttle valve by applying a varying voltage to the control circuits of the throttle actuator control
(TAC) motor. The ECM monitors the duty cycle that is required to actuate the throttle valve. The ECM monitors the throttle position sensors 1 and
2 to determine the actual throttle valve position.
Conditions for Running the DTC
* The vehicle speed is 0 km/h (0 mph).
* The engine speed is less than 40 RPM.
* The engine coolant temperature (ECT) is between 5-100掳C (41-212掳F).
* The intake air temperature (IAT) is between 5-143掳C (41-290掳F).
* The ignition voltage is greater than 10 volts.
* The accelerator pedal position (APP) is less than 15 percent.
* DTC P1551 runs when the conditions above have been met for greater than 5 seconds.
Conditions for Setting the DTC
* The ECM detects the TP sensor angle is less than 2 percent or greater than 13 percent when the throttle actuator control motor is deactivated.
* The condition exists for greater than 1 second or for a cumulative of 10 seconds.
Action Taken When the DTC Sets
DTC P1551 is a type A DTC.
Conditions for Clearing the DTC
DTC P1551 is a type A DTC.
Diagnostic Aids
* The scan tool has the ability to operate the throttle actuator control system using Special Functions. This function operates the throttle
through the entire range in order to determine if the throttle body and system operate correctly.
* Inspect for a condition in which the throttle valve may have been held open.
* Inspect for conditions in which ice may have formed in the throttle bore.
* The throttle valve is spring loaded to a slightly open position. This is referred to as the rest position. The throttle valve should not be
completely closed, nor should it be open any greater than predetermined amount. The throttle valve should move open and to the closed
position without binding under the normal spring pressure. The throttle should NOT be free to move open or closed WITHOUT spring
pressure.
Reference Information
Schematic Reference
Engine Controls Schematics (LAU) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)Engine Controls Schematics
(LF1) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views/Connector End Views By Name)
Description and Operation
Throttle Actuator Control (TAC) System Description (See: Powertrain Management/Computers and Control Systems/Description and
Operation/Throttle Actuator Control (TAC) System Description)
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)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
