Technical Description of OBD-II Trouble Code
The circuit for the Transmission Park Position Sensor/Switch A is registering a high voltage.
What does that mean?
This is a generic diagnostic trouble code (DTC) for powertrain issues that applies to OBD-II vehicles equipped with a transmission park position switch/sensor. This includes vehicles from various manufacturers such as Dodge, Ford, Toyota, Land Rover, VW, Chevrolet, and others. The specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
Trouble code P07B4 is one of several codes associated with malfunctions in the Transmission Park Position Sensor/Switch “A” Circuit.
This code indicates that the Powertrain Control Module (PCM) has detected a malfunction in the transmission park position sensor/switch “B” circuit, which is affecting its operation. The codes commonly associated with malfunctions in the transmission park position sensor/switch “A” circuit are P07B2, P07B3, P07B4, P07B5, P07B6, and P07B7. The specific code activated by the PCM and the illumination of the check engine light or service engine soon light depend on the specific situation.
The purpose of the transmission park position sensor/switch “A” 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 P07B4 is set by the PCM when it detects a high output voltage in the transmission park position sensor/switch “A” circuit.
What is the severity of this DTC?
The severity of this code varies depending on the specific malfunction, and it may escalate if not addressed promptly. If the starter engages while the vehicle is in gear, this code can become a safety issue that requires immediate attention.
Photo of a park/neutral position switch:
What are some of the symptoms of the code?
Symptoms of trouble code P07B4 may include:
What are some of the common causes of the code?
Possible causes for code P07B4 may include:
What are some P07B4 troubleshooting steps?
The first step in troubleshooting any malfunction is to research the Technical Service Bulletins for known issues with the specific vehicle.
Locate all the components associated with the transmission park position sensor/switch “A” circuit. These components include the transmission park position sensor/switch, wiring, connectors, and the PCM in a simplex system. Depending on the specific year, make, and model of the vehicle, this circuit may incorporate additional components. After locating these components, conduct a thorough visual inspection to check for any obvious defects such as scraping, rubbing, bare wires, or burn spots in the associated wiring and connectors. Also, check the connectors for corrosion buildup or damaged pins.
Advanced Steps
The advanced steps are highly specific to the vehicle and require advanced equipment for accurate execution. These procedures necessitate the use of 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 for the transmission park position sensor/switch circuit and its components will vary depending on the specific vehicle and circuit configuration. Refer to the technical data to obtain the correct voltage range for the transmission park position sensor/switch and follow the appropriate troubleshooting sequence. If a sensor/switch has no voltage output despite receiving the correct voltage input, it is usually an indication of internal failure.
If this process reveals the absence of a power source or ground, continuity testing may be necessary to check the condition of the wiring and connectors. Continuity tests should always be 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 lack of 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 guiding you towards resolving the issue with your transmission park position sensor/switch circuit. However, please note that this article is purely informational, and the specific technical data and service bulletins for your vehicle should always take precedence.
