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
* The 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
The 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.
* The TCM inhibits the sport mode shift pattern.
* The TCM inhibits Tap Up/Down function.
* The 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 (6T30/6T40/6T45 - Automatic Transmission)
Connector End View Reference
* Component Connector End Views (Connector End Views By Name)
* Inline Harness Connector End Views (Connector End Views By Number)
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 (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool ECM Fuel Economy Mode parameter. The parameter should display Inactive.
2. Command the Fuel Economy Mode ON and OFF with the Economy Mode switch and observe the Fuel Economy Mode parameter with a scan tool. The Fuel Economy Mode parameter should display Active or Inactive and change each time the Economy Mode switch is depressed.
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 Fuel Economy Mode switch.
2. Test for less than 5 ohm between the ground circuit terminal 1 of the harness connector and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance and repair as necessary.
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 of the harness connector and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Observe the scan tool Fuel Economy Mode Switch parameter. The parameter should display Circuit Low Voltage.
• If the parameter does not display the specified value, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
5. 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. Verify the scan tool Fuel Economy Mode Switch parameter displays Circuit High Voltage.
• If the parameter does not display the specified value, test the signal circuit for an open/high resistance or a short to ground. If the circuit tests normal, replace the ECM.
6. Test for 266-294 ohm between the 5 V reference voltage circuit terminal 3 of the switch and the signal circuit terminal 4 of the switch.
• If not the specified value, replace the economy mode switch
7. Test for 927-1024 ohm between signal circuit terminal 4 of the switch and low reference circuit terminal 1 of the switch.
• If not the specified value, replace the economy mode switch.
8. With the fuel economy mode switch button depressed, test for 220-244 ohm between terminal 4 of the switch and terminal 1 of the switch.
• If not the specified value, replace the economy mode switch.
9. If all circuits test normal, replace the ECM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Manual Shift Detent Lever with Shaft Position Switch Assembly Replacement (6T30/6T40/6T45 - Automatic Transmission)