2010 Cadillac Truck SRX FWD V6-3.0L Page 1000
* Engine coolant consumption-Refer to Loss of Coolant (See: Engine, Cooling and Exhaust/Cooling System/Testing and
Inspection/Symptom Related Diagnostic Procedures/Loss of Coolant).
瀚慖f you find any of the above conditions, repair as necessary.
2. If all conditions test normal, test or replace the appropriate B52 HO2S.
Repair Instructions
Caution: Refer to Heated Oxygen Sensor Resistance Learn Reset Caution (See: Powertrain Management/Computers and Control
Systems/Oxygen Sensor/Service Precautions/Heated Oxygen Sensor Resistance Learn Reset Caution).
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 (LF1) (See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair/Heated Oxygen Sensor Replacement - Bank 1 Sensor 1)
* Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 (LF1) (See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair/Heated Oxygen Sensor Replacement - Bank 1 Sensor 2)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 (LF1) (See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair/Heated Oxygen Sensor Replacement - Bank 2 Sensor 1)
* Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 (LF1) (See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair/Heated Oxygen Sensor Replacement - Bank 2 Sensor 2)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
P15A0
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.
