2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1116
* Heated Oxygen Sensor Replacement - Sensor 1 (LAU) (See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair/Heated Oxygen Sensor Replacement - Sensor 1)
* Heated Oxygen Sensor Replacement - Sensor 2 (LAU) (See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair/Heated Oxygen Sensor Replacement - Sensor 2)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for engine control module replacement, setup, and
programming
P159F
DTC P159F or P15A0
Diagnostic Instructions
* 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)provide an overview of each diagnostic category.
DTC Descriptors
DTC P159F
- Fuel Economy Mode Switch Circuit Low Voltage
DTC P15A0
- Fuel Economy Mode Switch Circuit High Voltage
Diagnostic Fault Information
Circuit Description
The ECM supplies 5 V reference voltage, through the 5 V reference voltage circuit, to the S87 fuel economy mode switch. The 5 V reference
voltage causes current to flow through a series of resistors in the switch to the switch ground circuit. The ECM monitors the reference voltage
through a discrete fuel economy mode switch signal circuit. When the switch button is momentarily pressed, the switch contacts allow the 5 V
reference voltage to by-pass one of the resistors. The ECM detects the resulting voltage drop as a fuel economy mode request and sends a GMLAN
message to the transmission control module (TCM) indicating the request. When the TCM receives the request, throttle progressions and
transmission shift points are modified to optimize fuel efficiency. The instrument panel cluster (IPC) also receives the fuel economy mode request
message from the ECM and illuminates the fuel economy mode indicator lamp. The fuel economy mode switch must be pressed for between
0.094-1.5 s to activate the fuel economy mode.
Conditions for Running the DTC
* Ignition key must be turned to ON.
* DTCs P159F and P15A0 run continuously when the above condition is met.
Conditions for Setting the DTC
The ECM detects that the voltage on the fuel economy mode switch signal wire is either too low or too high out of range.
Action Taken When the DTC Sets
DTCs P159F and P15A0 are Type B DTCs
Conditions for Clearing the MIL/DTC
DTCs P159F and P15A0 are Type B DTCs
Reference Information
Schematic Reference
Engine Controls Schematics (LAU) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)Engine Controls Schematics
