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P0851




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 Switch Circuit

DTC P0851
- Park/Neutral Position Switch Circuit Low Voltage

DTC P0852
- Park/Neutral Position 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, is a sliding contact switch attached to the manual shift shaft inside the transmission case. The park/neutral position switch is integrated into the internal mode switch and connects to the Transmission Control Module lead-frame through a short wire harness. The circuit uses the Transmission Control Module 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 11-18 volts.

* Engine Speed is 1000 RPM or greater.

* TP is 8 percent or greater.

* Engine torque is 75 Nm (55 lb ft) or greater.

* Vehicle speed is 10 km/h (6 mph) or greater.

Conditions for Setting the DTC

P0850 or P0851

The ECM detects the Park/Neutral switch signal equals 0 V, Low, when the IMS reports a Drive range.

P0852

The ECM detects the Park/Neutral switch signal equals 12 V, High, when the IMS reports a Park/Neutral range.

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

* Engine Controls Schematics (L99/LS3) [1][2]Electrical DiagramsEngine Controls Schematics (LSA) [1][2]Electrical Diagrams

Connector End View Reference

* Component Connector End Views Fuel Pump and Level Sensor Assembly - Primary

* Inline Harness Connector End Views X102

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

Special Tools

DT-47825-10 - Jumper Harness

For equivalent regional tools, refer to Special Tools Tools and Equipment.

Circuit/System Verification

1. Verify the range selector cable is adjusted correctly. Refer to Shift Control Linkage Adjustment Adjustments.

• If the cable adjustment is not OK
Adjust, repair or replace as necessary.

• If the cable adjustment is OK

2. Ignition ON.

3. Verify the scan tool Engine Control Module Park/Neutral Position Switch parameter displays Park/Neutral when in Park or Neutral and In-Gear when in Reverse or Drive Range.

• If Park/Neutral or In-Gear is not displayed
Refer to Circuit/System Testing.

• If Park/Neutral or In-Gear is displayed

4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observe from the Freeze Frame/Failure Records data.

5. Verify the DTC does not set.

• If the DTC sets
Refer to Circuit/System Testing.

• If the DTC does not set

6. All OK.

Circuit/System Testing

Note: You must perform Circuit/System Verification first.

1. Ignition OFF, disconnect the X1 harness connector at the Q8 Control Solenoid Valve Assembly on the automatic transmission.

2. Install the DT-47825-10 - jumper harness to the X1 vehicle harness connector.

3. Test for less than 5 ohms between the ground circuit terminal 5 at the DT-47825-10 - jumper harness and ground at the transmission case.

• If 5 ohms or greater

1. Ignition OFF.

2. Test for less than 2 ohms in the ground circuit from wire end to wire end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.

• If less than 2 ohms, repair the open/high resistance in the ground connection.

• If less than 5 ohms

4. Ignition ON.

5. Test for 11-13 V between the signal circuit terminal 3 at the DT-47825-10 - jumper harness and ground at the transmission case.

• If not between 11-13 V

1. Ignition OFF, disconnect the X1harness connector at the K20 Engine Control Module.

2. Test for infinite resistance between the Park/Neutral signal circuit terminal 3 at the DT-47825-10 - jumper harness and ground at the transmission case.

• 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 Park/Neutral signal circuit wire end to wire 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 between 11-13 V

6. Ignition OFF, disconnect the DT-47825-10 - jumper harness from the X1 vehicle harness connector.

7. Connect the DT-47825-10 - jumper harness to the Q8 Control Solenoid Valve Assembly harness connector at the transmission case.

8. Remove the transmission fluid pan.

9. Disconnect the B15 Transmission Internal Mode Switch electrical connector from the Q8 Control Solenoid Valve Assembly.

10. Test for less than 2 ohms between the ground circuit terminal 5 and terminal A at the B15 Transmission Internal Mode Switch connector on the Q8 Control Solenoid Valve Assembly.

• If 2 ohms or greater
Replace the Q8 control solenoid valve assembly.

• If less than 2 ohms

11. Ignition OFF.

12. Connect the DT-47825-10 - jumper harness to the X1 vehicle harness connector.

13. Ignition ON.

14. Test for 11-13 V between terminal F at the B15 Transmission Internal Mode Switch connector on the Q8 Control Solenoid Valve Assembly and ground at the transmission case.

• If not between 11-13 V
Replace the Q8 control solenoid valve assembly.

• If between 11-13 V

15. Connect a 3 A fused jumper wire between terminal F at the B15 Transmission Internal Mode Switch on the Q8 Control Solenoid Valve Assembly and ground at the transmission case.

16. Verify the scan tool Engine Control Module Park/Neutral Position Switch parameter displays Park/Neutral.

• If Park/Neutral is not displayed
Replace the K20 Engine Control Module.

• If Park/Neutral is displayed

17. Replace the B15 Transmission Internal Mode Switch.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Perform the Reset Transmission Adapts Reset Procedure following all transmission related repairs.

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

Note: If the IMS switch has been replaced, inspect the valve body detent spring to be sure it is centered over the detent lever. This prevents the detent spring from hitting the IMS switch.

* Manual Shift Shaft Position Switch Replacement Service and Repair for IMS replacement.

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