P0703: Brake Switch B Circuit
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes with care - but brake lights may be misbehaving, which endangers you from behind.
Symptoms
- Cruise control refusing to engage
- Harsh shifts or no converter lockout
- Brake lights stuck on or off
Likely causes, most common first
- Brake light switch worn or misadjusted
- Wiring at the pedal connector
- Blown brake light fuse
Read P0703 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0703 means the transmission computer sees an implausible brake switch signal. The same switch feeds brake lights, cruise control and shifter interlock - which is why one worn switch produces such a strange constellation of symptoms.
Have someone confirm your brake lights work today: the code's cheapest consequence is cruise control, its most dangerous is a car behind you getting no warning.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Frequently asked questions
Can I drive with P0703?
Yes with care - but brake lights may be misbehaving, which endangers you from behind.
How much does it cost to fix P0703?
Typical US repair costs range from $40 for the simplest fix (brake switch) to $200 in the worst case. The right number depends on which cause your car has - see the causes list.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.