P0703: Torque Converter/Brake Switch B Circuit Malfunction
Can you still drive? Yes, but check your brake lights first. If brake lights work, the issue is primarily with transmission shift feel. If brake lights are out, repair immediately for safety.
What Does P0703 Mean?
Code P0703 indicates a malfunction in the brake switch B circuit, which the transmission control system uses to manage torque converter lockup and shift strategies. When the TCM cannot detect brake pedal application, it may not unlock the torque converter or adjust shift timing during deceleration.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Faulty brake light switch
- Misadjusted brake light switch
- Open or shorted wiring in brake switch B circuit
- Blown fuse for brake switch circuit
- Corroded brake switch connector
Symptoms
- Check engine light on
- Torque converter not unlocking when braking
- Engine nearly stalling when coming to a stop
- Transmission not downshifting during braking
- Cruise control issues
Diagnostic Steps
- 1Verify brake lights are functioning properly
- 2Check brake switch adjustment at the brake pedal
- 3Test brake switch B circuit signal with a scan tool while pressing pedal
- 4Inspect brake switch wiring for damage or corrosion
- 5Check related fuses
- 6Test brake switch continuity and resistance
Recommended Parts & Tools
brake light switch
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $20 - $200 |
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Chat with AI About P0703Commonly Affected Vehicles
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Frequently Asked Questions
What is brake switch B?
Many vehicles have two separate brake switch circuits: one for brake lights and one for the transmission and cruise control. P0703 relates to the circuit used by the transmission control system.
Why does my car lurch when stopping with P0703?
The transmission cannot detect that you are braking, so the torque converter stays locked, causing the engine to lug and the vehicle to lurch as it comes to a stop.
Community Fix Reports
Community reports are user-submitted and not verified by Auto AI Buddy. Results may vary.
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