2010 Cadillac Truck SRX AWD V6-3.0L Page 1002
the K20 ECM.
瀚慖f greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
5. If all circuits test normal, test or replace the S87 fuel economy mode switch.
Component Testing
1. Ignition OFF, disconnect the S87 fuel economy mode switch.
2. Test for 266-294 ohm between 5 V reference voltage circuit terminal 9 and signal circuit terminal 10 of the S87 fuel economy mode switch.
瀚慖f not within the specified range, replace the S87 fuel economy mode switch.
3. Test for 1,414-1,562 ohm between 5 V reference voltage circuit terminal 9 and ground circuit terminal 2 of the S87 fuel economy mode
switch.
瀚慖f not within the specified range, replace the S87 fuel economy mode switch.
4. With the S87 fuel economy mode switch button depressed, test for 486-538 ohm between 5 V reference voltage circuit terminal 9 and ground
circuit terminal 2 of the S87 fuel economy mode switch.
瀚慖f not within the specified range, replace the S87 fuel economy mode switch.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
Control Module References (See: Testing and Inspection/Programming and Relearning)for ECM replacement, setup and programming
P15A1
DTC P15A1
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 Descriptor
DTC P15A1
- Fuel Economy Mode Switch Performance
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. This 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 5 V 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 signal 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 button must be pressed for between
0.094-1.5 s to activate the fuel economy mode.
Conditions for Running the DTC
* The ignition key is turned to ON.
* DTC P15A1 runs continuously when the above condition is met.
