DTC P0703 Torque Converter/Brake Switch B Circuit Malfunction

DTC P0703 is an OBD-II diagnostic trouble code that relates to a malfunction in the Torque Converter/Brake Switch B Circuit. This code is registered when the Powertrain Control Module (PCM) detects an electrical fault or irregularity within this specific circuit.

1. What does P0703 code mean?

DTC P0703 specifically points to a problem in the Torque Converter/Brake Switch B Circuit. It indicates that there’s an electrical issue or malfunction within this circuit, which is crucial for proper transmission control.

2. What are the causes of DTC P0703?

Potential causes of DTC P0703 may include:

  • Faulty Brake Switch: A malfunctioning or misadjusted brake switch causing improper transmission engagement signals.
  • Wiring Issues: Damaged, corroded, or disconnected wiring within the Torque Converter/Brake Switch B Circuit.
  • Faulty Torque Converter Clutch Solenoid: Problems within the solenoid impacting torque converter clutch engagement.

3. What are the symptoms of DTC P0703?

Symptoms associated with DTC P0703 might include:

  • Check Engine Light: Illumination of the Check Engine Light due to the detected electrical fault in the Torque Converter/Brake Switch B Circuit.
  • Transmission Issues: Possible transmission engagement problems, such as harsh shifting, delayed shifting, or failure to shift properly.
  • Decreased Fuel Efficiency: Transmission issues may lead to reduced fuel economy.

4. How to diagnose DTC P0703?

Diagnosing DTC P0703 involves several steps:

  • OBD-II Scan: Use an OBD-II scanner to retrieve the trouble code and any additional codes related to the transmission system.
  • Visual Inspection: Inspect the brake switch and related wiring for physical damage, corrosion, or disconnection.
  • Check Brake Switch Operation: Verify proper operation of the brake switch when the brake pedal is depressed.
  • Wiring Inspection: Use a multimeter to check for proper voltage and continuity within the Torque Converter/Brake Switch B Circuit.

5. How to fix DTC P0703 problem?

Potential steps to resolve DTC P0703 include:

  • Repair or Replace Faulty Components: Repair or replace any damaged wiring, connectors, or a malfunctioning brake switch identified during inspection.
  • Clear Codes: After fixing the issue, clear the trouble codes using an OBD-II scanner to reset the Check Engine Light.
  • Professional Assistance: Seek help from a certified mechanic for complex electrical issues or if further diagnosis and repair are needed.


DTC P0703, indicating an issue in the Torque Converter/Brake Switch B Circuit, requires a systematic inspection of the brake switch, related wiring, and the torque converter clutch solenoid. Addressing the root cause of the electrical fault is crucial to restore proper transmission functionality.