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Code P0863

Symptoms

• Check Engine Light is on

• Transmission may not shift properly

• Vehicle may enter limp mode

Common Causes

• Faulty Transmission Control Module (TCM)

• Damaged wiring or connectors in the communication circuit

• Faulty CAN bus network

Glossary

TCM: Transmission Control Module

CAN bus: Controller Area Network bus, a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other

Related Codes

• P0700

• P0600

Official description

TCM Communication Circuit

Laymans terms

This code means that the car's computer is having trouble talking to the part that controls the transmission. It's like when two people are trying to talk on the phone, but there's a bad connection.

Explanation

The Transmission Control Module (TCM) is not able to communicate properly with other control modules in the vehicle.

Technical description

The P0863 code indicates a problem with the communication circuit between the Transmission Control Module (TCM) and other modules in the vehicle, such as the Engine Control Module (ECM) or the Powertrain Control Module (PCM). This can be due to wiring issues, a faulty TCM, or problems with the CAN bus network.

Diagnosis steps

• Use an OBD-II scanner to confirm the code

• Inspect wiring and connectors related to the TCM

• Test the TCM for proper operation

Repair procedures

• Repair or replace damaged wiring or connectors

• Replace the faulty TCM

• Repair issues in the CAN bus network

Tools required

• OBD-II scanner

• Multimeter

• Wiring diagram

Estimated repair cost

$200 - $1000

Difficulty level

Moderate

Commonly affected vehicles

• Ford F-150

• Chevrolet Silverado

• Dodge Ram

Preventive measures

• Regularly check and maintain vehicle wiring

• Avoid exposure to moisture and extreme temperatures

• Perform routine vehicle diagnostics

Error code type

Communication Issue

User experience recommendations

• Avoid driving long distances until the issue is resolved

• Consult a professional mechanic for diagnosis and repair

Warranty information

Check with your vehicle manufacturer for warranty coverage on electronic components.

Historical data

The P0863 code has been reported in various vehicle models and is often related to communication issues within the vehicle's network.

Urgency level

Moderate – It should be addressed soon to avoid potential transmission problems.

Legal and safety notice

Driving with a malfunctioning transmission control system can be dangerous. Address this issue promptly to ensure vehicle safety.

Testing conditions

• Vehicle must be in a safe location

• Ensure the vehicle battery is fully charged

Component location

The TCM is typically located near the transmission or under the vehicle's dashboard.

FAQs

Q: Can I drive my car with a P0863 code?
A: It's not recommended to drive with this code, as it can lead to transmission issues.

Q: What happens if I ignore the P0863 code?
A: Ignoring this code can result in transmission failure and potentially more costly repairs.

Last updated: Jan 16, 2026 • Source: internal database
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