Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that there is a problem with the part of the car that helps control how the gears change in the transmission. It's like a switch that isn't working right.
The P1787 code is triggered when the transmission control module (TCM) detects an open circuit in the transmission ratio control actuator, which affects gear shifting.
The Transmission Ratio Control Actuator is responsible for adjusting the gear ratios within the transmission. An open circuit indicates that there is a break or disconnection in the electrical circuit that controls this actuator, preventing it from functioning properly.
• Check Engine Light is on
• Transmission may not shift properly
• Vehicle may go into 'limp' mode
• Faulty transmission ratio control actuator
• Damaged or corroded wiring or connectors
• Blown fuse related to the transmission control circuit
Transmission: A system in a vehicle that sends power from the engine to the wheels.
Actuator: A device that causes a mechanical system to operate.
• Use an OBD-II scanner to confirm the P1787 code
• Inspect wiring and connectors for damage or corrosion
• Test the transmission ratio control actuator for proper operation
• Replace or repair damaged wiring or connectors
• Replace the faulty transmission ratio control actuator
• Replace any blown fuses related to the transmission circuit
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Honda Accord
• Toyota Camry
• Ford F-150
• Regular maintenance of the transmission system
• Inspect and clean transmission connectors periodically
• Avoid harsh driving conditions that may strain the transmission
Transmission Control Issue
• Have the vehicle inspected by a professional if the Check Engine Light is on
• Avoid driving the vehicle if it is not shifting properly
• Schedule regular transmission maintenance
Check with your vehicle manufacturer for warranty coverage on transmission components.
This code has been reported in vehicles with higher mileage or those that have not had regular transmission maintenance.
Moderate – It is advisable to address this issue soon to prevent further transmission damage.
Driving with a malfunctioning transmission can be dangerous and may lead to further damage. It is recommended to address this issue promptly.
• Vehicle must be running
• Transmission must be engaged
The transmission ratio control actuator is located within the transmission housing.
Q: Can I drive with a P1787 code?
A: It's not recommended to drive with this code as it may lead to further transmission damage.
Q: How can I prevent a P1787 code?
A: Regular transmission maintenance and inspections can help prevent this code.
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