P080D High Jump Up/Down Shift Solenoid Control Circuit

P080D Fault Code:

Gear Shift Solenoid, Gear Engagement/Gear Skip – Strong Signal Circuit
Possible Cause:

Wiring, Gear Shift Solenoid, Transmission Control Module, Engine Control Module

P0810 Clutch Position Control Error

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Volvo, Toyota, Ford, Honda, Jeep, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0810 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the clutch position control system. This code applies only to vehicles with manual transmissions.

The clutch position sensor provides a secondary safety function to prevent the engine from starting when the transmission is engaged. It is typically a two-position switch that is open with the clutch pedal in the up position and closed when it is depressed. Clutch position sensors are usually located under the dashboard on the driver’s side, on the clutch pedal pivot arm bracket.

The Transmission Control Module (TCM) can be a standalone unit but is most often integrated into a single housing with the Engine Control Module (ECM). This is referred to as the PCM. The PCM calculates input data from the transmission input speed sensor, output speed sensor, and vehicle speed sensors to determine the desired position of the clutch pedal position sensor.

If the PCM detects a malfunction in the clutch position control circuit or detects that the clutch pedal is not in the correct position for current conditions, a P0810 code will be stored and a Malfunction Indicator Lamp (MIL) will illuminate. Several ignition cycles (with a fault) may be required for the MIL to illuminate.

How severe is this DTC?

A stored P0810 code indicates there is a problem in the clutch pedal position sensor circuit. Since the clutch pedal position sensor can disable engine starting or allow the engine to start with the transmission engaged, this code should be classified as severe.

What are some of the symptoms of the code?

Symptoms of a P0810 trouble code may include:

The starter will not engage the flywheel to start the engine
The engine starts with the transmission engaged
No symptoms may be present

What are some of the common causes of the code?

Causes of this code may include:

Faulty clutch position sensor
Open or shorted wiring or connectors in the clutch position sensor control circuit
TCM, PCM, or controller programming error or incorrect controller

What are the troubleshooting steps for P0810?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0810 code.

You can use your vehicle information source to locate a Technical Service Bulletin (TSB) that matches the vehicle’s year, make, and model; as well as engine size, stored codes, and presented symptoms. If you find one, it may provide useful diagnostic information.

Step 1

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is a good idea to record this information before clearing the codes, then test drive the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode at that point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.

Step 2

If the code resets immediately, the next step in your diagnosis will require you to consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.

Step 3

Use the DVOM to test the voltage and ground circuits at the clutch position sensor. If voltage and ground are present, use the DVOM to test the output of the clutch pedal position sensor.

Step 4

If the clutch pedal position sensor is functioning correctly, use the DVOM to test the system circuits. The voltage drop testing method works well for this task. Disconnect all controllers from the circuit before testing resistance with the DVOM.

If a P0810 code is stored in a vehicle with an automatic transmission, suspect a PCM/TCM failure or a programming error.

Excessive clutch slippage

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Audi, Volkswagen, Volvo, BMW, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0811 code, it means that the Powertrain Control Module (PCM) has received input data signals from the input and output speed sensors indicating that the clutch is slipping excessively.

The Transmission Control Module (TCM) may be a standalone unit but is most often integrated into a single housing with the Engine Control Module (ECM). This is referred to as the PCM.

The PCM uses input signals from various engine and transmission sensors to calculate the maximum allowable transmission (clutch) slip. Wear of the clutch disc and pressure plate, as well as mechanical failure, can lead to excessive clutch slippage. The PCM uses voltage input signals from the transmission input speed sensor and the transmission output speed sensor to determine if the clutch is operating within the parameters for maximum allowable slip.

As with many other transmission malfunctions, a clutch slippage code can be caused by an electrical or mechanical failure. Often, when the friction material on the clutch disc wears below a certain level, the clutch begins to slip. This condition is usually accompanied by the distinctive smell of burnt friction material.

If the PCM detects a degree of transmission (clutch) slip that exceeds the maximum allowable parameters, a P0811 code may be stored and a Malfunction Indicator Lamp (MIL) illuminated. Several ignition cycles (with a failure) may be required for the MIL to illuminate.

How severe is this DTC?

A stored P0811 code indicates that a serious electrical problem or a type of clutch failure has occurred. In any case, the conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.
What are some of the symptoms of the code?

Symptoms of a P0811 fault code may include:

Transmission slipping
Hard gear engagement
Clutch engagement occurs near the top
Strong smell of burnt friction material

What are some common causes of the code?

Causes

of this code may include:

Worn clutch disc and/or pressure plate
Faulty input or output speed sensor
Shorted wiring for the input/output speed sensors
Faulty PCM or programming error

What are the troubleshooting steps for P0811?

Before attempting to diagnose a P0811, ensure that the clutch, pressure plate, and release bearing are functioning correctly. You will also want to check the clutch arms and rings, as well as the clutch hydraulic system, if applicable.

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be necessary to diagnose a P0811 code. An oscilloscope may also be helpful when attempting to diagnose input and output speed sensor malfunctions.

With the clutch functioning properly, proceed to the first step of diagnosis.

Step 1

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is a good idea to note this information before clearing the codes, then test drive the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode at this point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.

Step 2

If the code resets immediately, the next step in your diagnosis will require you to search your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.

Step 3

Use the DVOM to test the voltage, ground, and signal at the transmission input and output speed sensors (key on, engine off). The input and output speed sensor circuits typically consist of a reference voltage wire, a signal wire, and a ground wire.

Step 4

Use the oscilloscope (connected to the signal circuit and ground) to check for spikes and dips in the speed sensor’s signal pattern.

Most transmission slippage codes are caused by excessively worn clutch components

P0812 Reverse Input Circuit

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Toyota, Honda, Acura, Lexus, Geo, General Motors, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0812 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the reverse input signal circuit.

The Transmission Control Module (TCM) can be a standalone module or part of the PCM. Like the TCM, the reverse light sensor for the transmission can be a single component or it can be part of the neutral safety switch. Vehicle applications with a manual transmission typically use a separate reverse position sensor, and automatic transmissions use the neutral safety switch.

The transmission controller calculates data from the vehicle speed sensor and wheel speed sensors to determine if the vehicle is moving or not; and in which direction. The PCM also performs periodic self-tests to ensure the system circuit voltage is within parameters.

If the PCM detects that the vehicle is moving in a reverse direction without the appropriate reverse sensor signal, a P0812 code may be stored and a Malfunction Indicator Lamp (MIL) illuminated. Several ignition cycles (with a failure) may be required for the MIL to light.

How severe is this DTC?

A stored P0812 code indicates that a serious electrical problem or a type of mechanical failure has occurred. In any case, the conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.
What are some of the symptoms of the code?

Symptoms of a P0812 trouble code may include:

Reverse lights are inoperative
Reverse lights are continuously on
No symptoms may be apparent

What are some of the common causes of the code?

Causes

of this code may include:

Faulty reverse position sensor
Faulty neutral safety switch
Shorted wiring for the reverse position sensor
Faulty PCM or programming error

What are the P0812 troubleshooting steps?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0812 code.

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It’s a good idea to record this information before clearing the codes, then test drive the vehicle until the PCM enters readiness mode or the code resets.

If the code immediately resets, the next step in your diagnosis will require you to consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.

Step 1

Use the DVOM to test the voltage, ground, and signal at the reverse position sensor or neutral safety switch. The input and output circuits of the reverse position sensor typically consist of either a reference voltage (transmission in reverse) or a ground (transmission not in reverse).

Step 2

If the system circuits are functional, use the DVOM to test the appropriate reverse position sensor. Replace sensors that do not test within system parameters.

Reverse position sensor codes are most often attributed to a sensor failure

P0813 Reverse Output Circuit

What does it mean?

This diagnostic code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Toyota, Honda, Acura, Lexus, Geo, General Motors, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0813 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the reverse output signal circuit.

The Transmission Control Module (TCM) can be a standalone module or part of the PCM. Like the TCM, the reverse sensor for the transmission can be a single component or it can be part of the neutral safety switch. Vehicle applications with a manual transmission typically use a separate reverse position sensor, and automatic transmissions use the neutral safety switch.

If the PCM detects that the vehicle is moving in a reverse direction without the appropriate reverse sensor signal, a P0813 code may be stored and a Malfunction Indicator Lamp (MIL) illuminated. Several ignition cycles (with a failure) may be required for the MIL to illuminate.

How severe is this DTC?

A stored P0813 code indicates that a serious electrical problem or a type of mechanical failure has occurred. In any case, the conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.
What are some of the symptoms of the code?

Symptoms of a P0813 fault code may include:

    Reverse lights are inoperative
    Reverse lights are continuously on
    No symptoms may appear

What are some of the common causes of the code?

Causes

of this code may include:

    Faulty reverse position sensor
    Faulty neutral safety switch
    Shorted wiring for the reverse position sensor
    Faulty PCM or programming error

What are the troubleshooting steps for P0813?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0813 code.

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is a good idea to record this information before clearing the codes, then test the vehicle until the PCM enters readiness mode or the code resets.

If the code is immediately reset, the next step in your diagnosis will require you to consult your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.

Step 1

Step 2

If the system circuits are functional, use the DVOM to test the appropriate reverse position sensor. Replace sensors that do not test within system parameters.

Reverse position sensor codes are most often attributed to sensor failure

P0814 Transmission Range Display Circuit

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Mercedes-Benz, Jaguar, Range Rover, Ford, Volvo, Sprinter, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0814 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the transmission range display circuit. This type of code is limited to vehicles with automatic transmissions.

The Transmission Control Module (TCM) may be a standalone module or part of the PCM. The transmission range display sensor is often integrated into the neutral safety switch. The transmission range display sensor is actuated by the shift lever and provides a voltage signal to the PCM and the Instrument Panel Control Module (IPCM) that reflects the specific gear that has been selected. Various engine and transmission outputs are monitored by the PCM to determine if the transmission range display sensor is in the appropriate position. Additionally, the PCM monitors the voltage of the transmission range sensor circuit to ensure it is within established parameters.

If the PCM detects that the vehicle is moving in a way that is not conducive to the gear selection input from the transmission range display sensor or if the circuit voltage is not within allowable parameters, a P0814 code may be stored and a Malfunction Indicator Lamp (MIL) illuminated. Several ignition cycles (with a failure) may be required for the MIL to illuminate.

How severe is this DTC?

A stored P0814 code indicates that a serious electrical problem or a type of mechanical failure has occurred. In any case, the conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.

What are some of the symptoms of the code?

Symptoms of a P0814 fault code may include:

The gear shift indicator (on the dashboard or console) is inoperative
The gear shift indicator reflects an incorrect gear
No start or engine starts with transmission engaged
No symptoms may appear

What are some common causes of the code?

Causes of this code may include:

Faulty transmission range display sensor
Short or open circuits in the transmission range display sensor circuit
Broken or faulty gear shift indicator
Faulty PCM or programming error

What are the troubleshooting steps for P0814?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0814 code.

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is a good idea to record this information before clearing the codes, then test the vehicle until the PCM enters readiness mode or the code resets.

Step 1

Use the DVOM to test the voltage, ground, and signal output at the transmission range display sensor or neutral safety switch. The input and output circuits of the transmission range display sensor typically consist of either reference voltage (drive gear) or ground (park or neutral).

Step 2

If the system circuits are functional, use the DVOM to test the transmission range display sensor. Replace sensors that do not test according to system specifications.

Transmission range display sensor codes are most often attributed to sensor failure

P0815 Shift Switch Circuit

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Ford, Acura, Vauxhall, Aston-Martin, Mercedes-Benz, Sprinter, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0815 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the shift switch circuit. This type of code is typically limited to vehicles equipped with paddle shifters.

The Transmission Control Module (TCM) may be a standalone module or part of the PCM. The shift buttons (paddles) are usually located on the steering wheel horn pad near the driver’s finger position. They are used as a type of sport shifter, typically in high-performance models. The PCM monitors the transmission gear selection against the shift switch input signals to ensure continuity. Additionally, the PCM monitors the voltage of the shift switch circuit to ensure it is within established parameters.

If the PCM detects that the transmission gear selection does not match the gear selection signal input from the shift switch, or if the switching circuit voltage is not within allowed parameters, a P0815 code may be stored and a Malfunction Indicator Lamp (MIL) illuminated. Several ignition cycles (with a failure) may be required for MIL illumination.

How severe is this DTC?

A stored P0815 code indicates that a serious electrical problem or mechanical failure type has occurred. In any case, the conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.
What are some of the symptoms of the code?

Symptoms of a P0815 fault code may include:

    Manual gear shift function (paddle) disabled
    Gear shift indicator displays incorrect gear
    No symptoms may be apparent

What are some common causes of the code?

Causes

of this code may include:

    Faulty gear shift switch
    Short or open circuits in the shift switch circuit
    Faulty PCM or programming error

What are the P0815 troubleshooting steps?

A diagnostic scanner, digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0815 code.

If the PCM enters readiness mode at that point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to the code storage may need to worsen before an accurate diagnosis can be made.

Step 1

Use the DVOM to test voltage, ground, and signal output at the appropriate shift switch. Typical gear shift switching circuits consist of battery voltage (when activated) or ground (when deactivated).

Step 2

If the system circuits are functional, use the DVOM to test the gear shift switching circuits to the PCM or transmission. Disconnect all controllers before using the DVOM for testing.

Step 3

Use your vehicle diagnostic information source and DVOM to test shift switches as needed. Replace switches that do not test within system specifications.

Shift codes are most often attributed to switch failure

P0816 Downshift Switching Circuit

What Does It Mean?

If your vehicle has stored a P0816 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the downshift switch circuit. This type of code is typically limited to vehicles equipped with paddle shifters.

The Transmission Control Module (TCM) may be a standalone module or part of the PCM. The downshift shift buttons (paddles) are usually located on the steering wheel horn pad near the driver’s finger position. They are used as a type of sport shifter, typically in high-performance models. The PCM monitors the transmission gear selection against the input signals from the downshift switch to ensure continuity. Additionally, the PCM monitors the voltage of the downshift switch circuit to ensure it falls within established parameters.

If the PCM detects that the transmission gear selection does not match the gear selection signal input from the downshift switch, or if the switching circuit voltage is not within the allowed parameters, a P0816 code may be stored and a Malfunction Indicator Lamp (MIL) illuminated. Several ignition cycles (with a failure) may be required for the MIL to light up.

How Severe Is This DTC?

A stored P0816 code indicates that a serious electrical issue or a type of mechanical failure has occurred. In any case, the conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.
What Are Some of the Symptoms of the Code?

Symptoms of a P0816 fault code may include:

    Manual downshift function (paddle) disabled
    Gear shift indicator reflects an incorrect gear
    No symptoms may appear

What Are Some Common Causes of the Code?

Causes

of this code may include:

    Faulty downshift switch
    Short or open circuits in the downshift switch circuit
    Faulty PCM or programming error

What Are the P0816 Troubleshooting Steps?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0816 code.

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is a good idea to record this information before clearing the codes, then test the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode at that point, the code is intermittent and may be much harder to diagnose. If this is the case, the conditions that contributed to the code storage may need to worsen before an accurate diagnosis can be made.

Step 1

Use the DVOM to test the voltage, ground, and signal output at the appropriate downshift switch. Typical downshift switching circuits consist of battery voltage (when activated) or ground (when deactivated).

Step 2

If the system circuits are functional, use the DVOM to test the downshift switching circuits to the PCM or transmission. Disconnect all controllers before using the DVOM for testing.

Step 3

Use your vehicle diagnostic information source and the DVOM to test the downshift switches as needed. Replace switches that do not test within system specifications.

Downshift switching codes are most often attributed to a switch failure

P0817 Starter Disable Circuit

What does it mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Subaru, BMW, Mazda, Volkswagen, Audi, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0817 code, it means that the Powertrain Control Module (PCM) has detected a malfunction in the starter disable switch circuit. This type of code can be applicable to vehicles with manual or automatic transmissions.

The starter disable switch is typically a single-circuit open/closed switch that interrupts voltage between the ignition switch and the starter solenoid if the clutch is not depressed, the (manual) transmission is not in neutral, or the (automatic) transmission is not in park. Vehicle applications with an automatic transmission may have the starter disable switch integrated into the neutral safety switch or the gear selector. The Transmission Control Module (TCM) or the PCM monitors the starter disable circuit voltage with the ignition in the ON position. The TCM can be a standalone module or part of the PCM.

If the PCM detects that the voltage in the starter disable switch circuit is not within the allowed parameters, a P0817 code may be stored and a Malfunction Indicator Lamp (MIL) illuminated. Several ignition cycles (with a failure) may be required for the MIL to illuminate.

How severe is this DTC?

A stored P0817 code may be accompanied by a no-start condition and also indicates that an electrical issue or mechanical failure has occurred. The conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.
What are some of the symptoms of the code?

Symptoms of a P0817 fault code may include:

Engine does not crank
Engine cranks with transmission in gear
No symptoms may be present

What are some of the common causes of the code?

Causes

of this code may include:

Faulty starter disable switch
Shorted or open wiring or connectors in the starter disable switch circuit
Faulty PCM or programming error

What are the troubleshooting steps for P0817?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be necessary to diagnose a P0817 code.

Use the DVOM to test the voltage, ground, and signal output at the appropriate starter disable switch. Typical starter disable switch circuits consist of battery voltage (when activated) or ground (when deactivated).
Step 2

Use your vehicle diagnostic information source and the DVOM to test the starter disable switches, if necessary. Replace switches that do not test within system parameters.
Step 3

If the system switches and circuits are functional, use the DVOM to test the starter disable switch circuits to the starter, as well as to the PCM. Disconnect all controllers before using the DVOM for testing.

Starter disable switch circuit codes are most often attributed to a switch failure
Vehicles with manual transmissions often use multiple starter disable switches (one for the clutch and another for neutral)

Transmission Shift Disconnect Switch Input Circuit

What Does It Mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Toyota, Land Rover, Volvo, BMW, Mini, Jaguar, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.

If your vehicle has stored a P0818 code, it means that the powertrain control module (PCM) has detected a malfunction in the transfer case neutral safety switch circuit (also known as the shift selector switch). This type of code applies only to vehicles equipped with AWD/4WD automatic transmissions.

The transfer case neutral safety switch input circuit is typically integrated into the neutral safety switch or the shift selector. When the transfer case is placed in neutral (drivetrain disconnected), a voltage signal is input to the transmission control module (TCM) or the PCM. The controller also monitors the voltage of the transfer case neutral safety switch circuit whenever the ignition is in the ON position. The TCM may be a standalone module or part of the PCM.

If the PCM does not detect an appropriate voltage level on the transfer case neutral safety switch circuit, with the transfer case apparently in gear or neutral, a P0818 code may be stored and a malfunction indicator lamp (MIL) illuminated. Multiple ignition cycles (with a failure) may be required for the MIL to light up.

How Severe Is This DTC?

A stored P0818 code may be accompanied by a no-start condition and also indicates that an electrical issue or a serious mechanical failure has occurred. The conditions that contributed to storing a code of this nature should be rectified as soon as possible.
What Are Some of the Symptoms of the Code?

Symptoms of a P0818 fault code may include:

Engine does not start
Front axle does not engage or disengage
Engine starts with the transmission in gear
No symptoms may be present

What Are Some Common Causes of the Code?

Causes

of this code may include:

Faulty neutral safety switch or shift selector
Shorted or open wiring or connectors in the transfer case neutral safety switch input circuit
Faulty PCM or programming error

What Are the P0818 Troubleshooting Steps?

A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be needed to diagnose a P0818 code.

You can use your vehicle information source to locate a technical service bulletin (TSB) that matches the vehicle’s year, make, and model; as well as engine size, stored codes, and presented symptoms. If you find one, it may provide useful diagnostic information.

Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is a good idea to record this information before clearing the codes, then test the vehicle until the PCM enters readiness mode or the code resets.

If the PCM enters readiness mode at that point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to storing the code may need to worsen before an accurate diagnosis can be made.

Use the DVOM to test the voltage input of the transfer case neutral safety switch with the gear lever in different positions. Typical transfer case neutral safety switch input circuits consist of either battery voltage (when activated) or ground (when deactivated).
Step 2

Use your vehicle diagnostic information source and the DVOM to test the neutral safety/shift selector switches, if necessary. Replace switches that do not test within system parameters.
Step 3

If the system switches and circuits are functional, use the DVOM to test the transfer case neutral safety switch input circuits to the PCM. Disconnect all controllers before using the DVOM for testing.

Transfer case neutral safety switch input codes are most often attributed to a failure of the neutral safety switch