Technical Description of OBD-II Trouble Code
The circuit for the Transmission Park Position Sensor/Switch B is open.
What does that mean?
This is a generic diagnostic trouble code (DTC) for the powertrain and applies to OBD-II vehicles that have a transmission park position switch/sensor. This includes vehicles from various manufacturers such as Dodge, Ford, Toyota, Land Rover, VW, Chevrolet, etc. The exact repair steps may vary depending on the year, make, model, and powertrain configuration.
Trouble code P07B8 is one of several codes associated with the Transmission Park Position Sensor/Switch “B” Circuit.
This code indicates that the Powertrain Control Module (PCM) has detected a malfunction in the transmission park position sensor/switch “B” circuit. The codes commonly associated with transmission park position sensor/switch “B” circuit malfunctions are P07B8, P07B9, P07BA, P07BB, P07BC, and P07BD. The specific code activated by the PCM will depend on the specific situation, and the check engine light or service engine soon light will be illuminated.
The purpose of the transmission park position sensor/switch “B” circuit is to monitor the status of the transmission. This circuit sends a signal to the PCM when the transmission is in the park position. In many vehicles, this circuit serves as a safety feature to prevent the starter from engaging when the automatic transmission is in gear.
Code P07B8 is set by the PCM when an open circuit is detected in the transmission park position sensor/switch “B” circuit.
What is the severity of this DTC?
The severity of this code varies depending on the specific malfunction, and it may become a safety issue if the starter engages while the vehicle is in gear. Therefore, it requires timely attention.
Photo of a park/neutral position switch:
What are some of the symptoms of the code?
Symptoms of a P07B8 trouble code may include:
What are some of the common causes of the code?
Causes for this P07B8 code may include:
What are some P07B8 troubleshooting steps?
The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins for known issues with the specific vehicle.
Locate all of the components associated with the transmission park position sensor/switch “B” circuit. This will include the transmission park position sensor/switch, wiring, connectors, and the PCM on a simplex system. Depending on the specific year, make, and model of the vehicle, this circuit may incorporate more components. After locating these components, conduct a thorough visual inspection to check all of the associated wiring and connectors for obvious defects such as scraping, rubbing, bare wires, or burn spots. Also, check the connectors for corrosion buildup or damaged pins.
Advanced Steps
The advanced steps are vehicle-specific and require the appropriate advanced equipment for accurate performance. These procedures require a digital multimeter and the specific technical references for the vehicle. The voltage requirements will vary based on the specific year, make, and model of the vehicle.
Circuit Checks
The voltage requirements will vary based on the specific vehicle, the transmission park position sensor/switch circuit configuration, and the incorporated components. Refer to the technical data to obtain the correct voltage range for the transmission park position sensor/switch and the appropriate troubleshooting sequence to follow. A sensor/switch with no voltage output despite receiving the correct voltage input usually indicates internal failure.
If this process identifies the absence of a power source or ground, continuity testing may be needed to check the condition of the wiring and connectors. Continuity tests are always performed with the power removed from the circuit, and the normal readings should be 0 ohms of resistance unless otherwise specified by the technical data. Resistance or no continuity indicates faulty wiring or connectors that are shorted or open and must be repaired or replaced.
Common Repairs
We hope that the information in this article has been helpful in addressing the problem with your transmission park position sensor/switch circuit. However, please note that this article is strictly informational, and the specific technical data and service bulletins for your vehicle should always take priority.
