SFI SYSTEM, Diagnostic DTC:P0851, P0852

DTC Code	DTC Name
P0851	Park / Neutral Switch Input Circuit Low
P0852	Park / Neutral Switch Input Circuit High

DESCRIPTION

DTC No.

DTC Detection Condition

Trouble Area

P0851

for Manual Transmission

No non-neutral position detected in shift change running state (judged based on changes in the relationship between vehicle speed and engine speed) (2 trip detection logic)

for Automatic Transmission

The CAN data received from the TCM is "P or N" position signal while the park/neutral position switch assembly is not in P or N position. (2 trip detection logic)

for Manual Transmission

Open or short in neutral position switch signal circuit
Neutral position switch
ECM

for Automatic Transmission

Open or short in park/neutral position switch signal circuit
Park/neutral position switch assembly
ECM
TCM

P0852

for Manual Transmission

No neutral position detected in shift change running state (judged based on changes in the relationship between vehicle speed and engine speed) (2 trip detection logic)

for Automatic Transmission

The CAN data received from the TCM is other than "P or N" position signal while the park/neutral position switch assembly is in P or N position. (2 trip detection logic)

for Manual Transmission

Open or short in neutral position switch signal circuit
Neutral position switch
ECM

for Automatic Transmission

Open or short in park / neutral position switch signal circuit
Park/neutral position switch assembly
ECM
TCM

MONITOR DESCRIPTION

for Manual Transmission

The ECM detects the shift change status from the neutral position switch signal, and detects the current selected gear from the engine speed and vehicle speed. If the neutral position switch signal and the shift change status cannot be coordinated, the ECM interprets this as a malfunction, illuminates the MIL, and stores the DTC.

for Automatic Transmission

If the ECM cannot coordinate the N, P or neutral information from the park/neutral position switch signal with the shift information sent from the TCM through CAN communication, then the ECM interprets this as a malfunction, illuminates the MIL, and stores the DTC.

CONFIRMATION DRIVING PATTERN

Connect the GTS to the DLC3.
Turn the ignition switch to ON and turn the GTS on.
Clear DTCs (even if no DTCs are stored, perform the clear DTC operation) Click here.
Turn the ignition switch off and wait for at least 30 seconds.
Turn the ignition switch to ON and turn the GTS on.
Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.
Change gear position 3 times or more during Accelerating vehicle to 64 km/h (40 mph) [A]. (for Manual Transmission)

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Drive the vehicle at 10 km/h (6.25 mph) or more for 1 minute or more [B]. (for Automatic Transmission)

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.
Enter the following menus: Powertrain / Engine / Trouble Codes.
Read pending DTCs.
Tech Tips
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
Enter the following menus: Powertrain / Engine / Utility / All Readiness.
Input the DTC: P0851 or P0852.

Check the DTC judgment result.

GTS Display	Description
NORMAL	DTC judgment completed System normal
ABNORMAL	DTC judgment completed System abnormal
INCOMPLETE	DTC judgment not completed Perform driving pattern after confirming DTC enabling conditions
N/A	Unable to perform DTC judgment Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

Tech Tips

If the judgment result shows NORMAL, the system is normal.
If the judgment result shows ABNORMAL, the system has a malfunction.

If the test result is INCOMPLETE or N/A and no DTC is output, perform a universal trip and check for permanent DTCs Click here.
Tech Tips
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

A004HHQE03

for Manual Transmission
*a	Neutral Position Switch

A004II9E03

for Automatic Transmission
*a	Park/Neutral Position Switch Assembly

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tech Tips

Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
Stop light switch assembly conditions can be checked using the GTS.

Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / Engine / Data List / Stop Light Switch and ST1.

Check the Data List indication when the brake pedal is depressed and released.

Brake Pedal Operation	Stop Light Switch	ST1
Depressed	ON	ON
Released	OFF	OFF

PROCEDURE

CHECK VEHICLE TYPE

Confirm the transmission.

Result
Result	Proceed to
for Manual Transmission	A
for Automatic Transmission	B

B

INSPECT TERMINAL VOLTAGE (POWER SOURCE OF PARK/NEUTRAL POSITION SWITCH ASSEMBLY) Click here

A

INSPECT TERMINAL VOLTAGE (POWER SOURCE OF NEUTRAL POSITION SWITCH)

Text in Illustration

*a
Front view of wire harness connector

(to Neutral Position Switch)

Disconnect the neutral position switch connector.

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Condition	Specified Condition
A54-1 - A54-2	Ignition switch ON	11 to 14 V

NG

CHECK HARNESS AND CONNECTOR (NEUTRAL POSITION SWITCH - ECM) Click here

OK

INSPECT NEUTRAL POSITION SWITCH
1. Inspect the neutral position switch Click here.
OK
CHECK FOR INTERMITTENT PROBLEMS Click here

NG
REPLACE NEUTRAL POSITION SWITCH Click here

CHECK HARNESS AND CONNECTOR (NEUTRAL POSITION SWITCH - ECM)

Disconnect the ECM connector.
Disconnect the neutral position switch connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for open)

Tester Connection	Condition	Specified Condition
A33-16 (NSW) - A54-2	Always	Below 1 Ω
A33-4 (EC) - A54-1	Always	Below 1 Ω

Standard Resistance (Check for short)

Tester Connection	Condition	Specified Condition
A33-16 (NSW) or A54-2 - Body ground	Always	10 kΩ or higher
A33-4 (EC) or A54-1 - Body ground	Always	10 kΩ or higher

OK

REPLACE ECM Click here

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

INSPECT TERMINAL VOLTAGE (POWER SOURCE OF PARK/NEUTRAL POSITION SWITCH ASSEMBLY)

Text in Illustration

*a
Front view of wire harness connector

(to Park/Neutral Position Switch Assembly)

Disconnect the park/neutral position switch assembly connector.

Measure the voltage according to the value(s) in the table below.

Standard Voltage

Tester Connection	Condition	Specified Condition
L2-4 - L2-5	Ignition switch ON	11 to 14 V

NG

CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH ASSEMBLY - ECM - BODY GROUND) Click here

OK

INSPECT PARK/NEUTRAL POSITION SWITCH ASSEMBLY
1. Inspect the park/neutral position switch assembly Click here.
OK
CHECK FOR INTERMITTENT PROBLEMS Click here

NG
REPLACE PARK/NEUTRAL POSITION SWITCH ASSEMBLY Click here

CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH ASSEMBLY - ECM - BODY GROUND)

Disconnect the ECM connector.
Disconnect the park/neutral position switch assembly connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for open)

Tester Connection	Condition	Specified Condition
A33-16 (NSW) - L2-4	Always	Below 1 Ω
L2-5 - Body ground	Always	Below 1 Ω

Standard Resistance (Check for short)

Tester Connection	Condition	Specified Condition
A33-16 (NSW) or L2-4 - Body ground	Always	10 kΩ or higher

OK

REPLACE ECM Click here

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR