2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1116

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