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6T70/6T75 - Automatic Transmission




DTC P0850-P0852

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 Descriptors
DTC P0850
- Park/Neutral Position (PNP) Switch Circuit

DTC P0851
- Park/Neutral Position (PNP) Switch Circuit Low Voltage

DTC P0852
- Park/Neutral Position (PNP) Switch Circuit High Voltage

Diagnostic Fault Information






Typical Scan Tool Data






Circuit/System Description

The transmission manual shift shaft switch assembly, also known as the Internal Mode Switch (IMS), is a sliding contact switch attached to the manual shift shaft inside the transmission case. The Park/Neutral Position (PNP) Switch is integrated into the IMS and connects to the Transmission Control Module (TCM) lead-frame through a short wire harness. The circuit uses the TCM as a pass-through connector only. The Park/Neutral Signal is sent from the park/neutral switch directly to the engine control module (ECM) and is used for engine start enable.

Conditions for Running the DTC

* Ignition voltage is between 8-18 volts.
* Engine speed is greater than 1000 RPM.

Conditions for Setting the DTC

P0850 and P0851
* The ECM detects the Park/Neutral switch signal equals 0 volts (Park/Neutral) when the IMS reports a Drive range for 0.2 second.
* The throttle position is 10 percent or greater.
* The engine torque is 75 Nm (55 lb ft) or greater.
* The vehicle speed is 10 km/h (6 mph) or greater.

P0852

The ECM detects the Park/Neutral switch signal equals 12 volts (In-Gear) when the IMS reports a Park/Neutral range for 0.2 second.

Action Taken When the DTC Sets

* DTCs P0850, P0851, and P0852 are Type C DTCs.
* The ECM uses IMS Range for engine start-up.

Conditions for Clearing the DTC

DTCs P0850, P0851, and P0852 are Type C DTCs.

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics Electrical Diagrams
Connector End View Reference

* Component Connector End Views Connector End Views By Name
* Inline Harness Connector End Views Connector Views

Description and Operation

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
Special Tools

DT-47825-20 Adapter Harness

Circuit/System Verification

1. If there are any other transmission DTCs set, diagnose those DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Perform the Range Selector Lever Cable Adjustment Adjustments procedure to verify proper adjustment.
3. Ignition ON, observe the scan tool ECM PNP Switch parameter while moving the gear shift lever from Park and through all ranges. The parameter should display Park/Neutral when in Park or Neutral and In-Gear when in Reverse or Drive.
4. Observe the scan tool TCM IMS A/B/C/P parameter while slowly moving the gear shift lever from Park through all ranges. The parameter should match each gear range that is selected. Refer to Transmission Internal Mode Switch Logic Transmission Internal Mode Switch Logic.
5. 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 first.

1. Ignition OFF, disconnect the 20-way harness connector at the transmission.
2. Connect the DT-47825-20 - harness to the vehicle wire harness 20-way transmission connector.
3. Test for less than 10 ohms between the ground circuit terminal 18 at the DT-47825-20 - harness and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

4. Disconnect the DT-47825-20 - harness from the vehicle wire harness 20-way transmission connector.
5. Remove the control valve body cover.
6. Connect the vehicle wire harness 20-way transmission electrical connector to the control solenoid valve assembly.
7. Disconnect the IMS connector at the control solenoid valve assembly.
8. Ignition ON, verify the scan tool ECM PNP Switch parameter displays In Gear.

• If not the specified value, test the Park/Neutral signal circuit for a short to ground. If the circuit tests normal, replace the engine control module.

9. Verify the scan tool TCM IMS A/B/C/P parameter displays HI for all four signal circuits.

• If not the specified value, replace the control solenoid valve assembly. Refer to Control Solenoid Valve and Transmission Control Module Assembly Replacement Service and Repair.

10. Connect a 3-amp fused jumper wire between Park/Neutral signal circuit terminal F and ground circuit terminal A on the control solenoid valve assembly. Verify the ECM PNP Switch parameter changes to Park/Neutral.

• If not the specified value, test the Park/Neutral signal circuit for an open/high resistance. If the circuit tests normal, replace the engine control module.

11. Connect a 3-amp fused jumper wire between each transmission range signal circuit terminal listed below and the IMS ground circuit, terminal A on the control solenoid valve assembly. Verify the corresponding scan tool TCM IMS A/B/C/P parameter displays LOW when terminal E, D, C, or B is connected to terminal A.

* Switch Signal A terminal E to ground circuit terminal A.
* Switch Signal B terminal D to ground circuit terminal A.
* Switch Signal C terminal C to ground circuit terminal A.
* Switch Signal P terminal B to ground circuit terminal A.

• If not the specified value, replace the control solenoid valve assembly.

12. If all circuits test normal, replace the transmission internal mode switch.

Repair Instructions

Note:
* Perform the Reset Transmission Adapts Programming and Relearning following all transmission related repairs.
* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Component Tests and General Diagnostics.

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Control Module References Control Module References for ECM or control solenoid valve assembly replacement, setup, and programming
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