P071D
DTC P071D
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P071D
- Transmission Sport Mode Switch circuit
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) supplies 5 V reference voltage, through the 5 V reference voltage circuit, to the 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 also supplies a signal circuit to detect voltage within the resistor network. When the fuel economy mode switch button is momentarily pressed, the switch contacts allow the current to by-pass one of the resistors. The ECM detects the resulting change in 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, and if operating conditions are correct, the transmission shift points are modified to optimize fuel efficiency. The TCM sends a confirmation message to the ECM and the instrument panel cluster (IPC) also receives the fuel economy mode request message from the TCM and illuminates the fuel economy mode indicator lamp.
Conditions for Running the DTC
* Engine speed is greater than 500 RPM for 5 seconds.
* Ignition voltage is between 9.0 volts and 19.0 volts.
Conditions for Setting the DTC
TCM detects that the Economy Mode Switch has been continuously activated for 10 minutes.
Action Taken When the DTC Sets
* DTC P071D is a type C DTC.
* TCM inhibits the sport mode shift pattern.
* TCM inhibits Tap Up/Down function.
* TCM inhibits manual shifting of forward gears.
Conditions for Clearing the DTC
DTC P071D is a Type C DTC.
Diagnostic Aids
Diagnose all communication and body DTCs first.
Reference Information
Schematic Reference
Automatic Transmission Controls Schematics Electrical Diagrams
Connector End View Reference
* Component Connector End Views Fuel Pump and Level Sensor Assembly
* Inline Harness Connector End Views X100
Description and Operation
* Transmission General Description Transmission General Description
* Transmission Component and System Description Transmission Component and System Description
* Electronic Component Description Electronic Component Description
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the Fuel Economy Mode parameter changes between Active and Inactive each time the S112 fuel economy mode switch is depressed.
• If the Fuel Economy Mode parameter does not change from Inactive to Active, or Active to Inactive
Refer to Circuit/System Testing below.
• If the Fuel Economy Mode parameter changes from Inactive to Active, or Active to Inactive
3. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, then STOP. Do not perform the Circuit/System Testing or Component Testing as this may result in an unnecessary part replacement. Refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.
Circuit/System Testing
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. Ignition OFF, disconnect the X1 harness connector at the S112 fuel economy mode switch.
2. Test for less than 10 ohms between the ground circuit terminal 1 of the harness connector and ground.
• If 10 ohms or greater
Test for less than 2 ohms in the ground circuit, end to end.
• If 2 ohms or greater, repair the open/high resistance in the ground circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 3 of the harness connector and ground.
• If less than 4.8 volts
1. Ignition OFF, remove the harness connector at the ECM.
2. Test for infinite resistance between the 5 V reference circuit terminal 3 of the harness connector and ground.
• If less than infinite resistance, repair the short to ground in the circuit.
• If infinite resistance.
3. Test for less than 2 ohms in the 5 V reference circuit, end to end.
• If 2 ohms or greater, repair the open/high resistance in the 5 V reference circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the ECM, ignition ON.
2. Test for less than 1 V between 5 V reference circuit terminal 3 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 engine control module.
• If between 4.8-5.2 volts
5. Verify the scan tool Fuel Economy Mode Switch parameter displays Circuit Low Voltage.
• If the Fuel Economy Mode Switch parameter does not display Circuit Low Voltage
1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the fuel economy signal circuit terminal 4 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 engine control module.
• If the Fuel Economy Mode Switch parameter displays Circuit Low Voltage
6. Connect a 3 A fused jumper wire between 5 V reference circuit terminal 3 of the harness connector and signal circuit terminal 4 of the harness connector.
7. Verify the scan tool Fuel Economy Mode Switch parameter displays Circuit High Voltage.
• If the Fuel Economy Mode Switch parameter does not display Circuit High Voltage
1. Ignition OFF, remove the connector at the K20 engine control module.
2. Test for infinite resistance between signal circuit terminal 4 and ground.
• If less than infinite resistance, repair the short to ground in the signal circuit.
• If infinite resistance.
3. Test for less than 2 ohms in the fuel economy mode signal circuit, end to end.
• If 2 ohms or greater, repair the open/high resistance in the signal circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If the Fuel Economy Mode Switch parameter displays Circuit High Voltage
8. Ignition OFF.
9. Test for 266-294 ohms between the 5 V reference voltage circuit terminal 3 and the signal circuit terminal 4 on the S112 fuel economy mode switch.
• If not between 266-294 ohms
Replace the S112 fuel economy mode switch.
• If between 266-294 ohms
10. Test for 927-1024 ohms between signal circuit terminal 4 and low reference circuit terminal 1 on the S112 fuel economy mode switch.
• If not between 927-1024 ohms
Replace the S112 fuel economy mode switch.
• If between 927-1024 ohms
11. Test for 220-244 ohms between terminal 4 and terminal 1 on the S112 fuel economy mode switch, with the switch pressed.
• If not between 220-244 ohms
Replace the S112 fuel economy mode switch.
• If between 220-244 ohms
12. Replace the K20 engine control module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Manual Shift Detent Lever with Shaft Position Switch Assembly Replacement Service and Repair