What Is the P0703 Code?
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The P0703 code signals a malfunction with the “Brake Switch “B” Circuit.” It means that the powertrain control module, or the PCM, has detected values from the brake switch that are not within the accepted values.
The P0703 code can be seen in cars that are equipped with OBD-II with an automatic transmission. When a P0703 code is stored, it means that there is something wrong with your brake or torque converter clutch (TCC) switch.
A P0703 code often means that the PCM has detected accelerations or decelerations without the brake pedal being activated. Or, it might refer to a failure of the torque converter to lock up or disengage.
What Brands Will This Code Cover?
A P0703 code affects all OBD-II vehicles, which include, but are not limited to, the following brands:
- Honda
- Mazda
- Mercedes
- Volkswagen
More About the P0703 Code
The P0703 code can refer to a failure of the brake pedal or the torque converter clutch TCC.
A torque converter is a type of fluid coupling found in automatic vehicles. When a car is moving, the torque converter can transfer the torque from the engine to the transmission. This means that a vehicle can come to a complete stop without stalling the engine.
However, this ability to ‘slip’ and prevent the engine from stalling also applies at higher speeds. Because of this ‘slip,’ the torque converter can never truly match an engine’s speed; this causes less efficient fuel mileage.
To counter this, some torque converters come with a lockup clutch. This allows the engine to lock into the transmission input shaft when certain speeds are reached. As the car slows down, the torque converter lockup disengages. This means that a car can function much like a manual vehicle, with better fuel efficiency.
If the torque converter lockup doesn’t disengage at the correct time or at all, then it will cause the engine to stall. The signal for the lockup to disengage often comes from the brake pedal. A signal is sent to the PCM when the brake pedal is applied; another signal is sent when the brake light switch is illuminated. The PCM stores a P0703 code when it senses a malfunction in one of these signals.
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What Are the Symptoms of a P0703 Code?
Common symptoms of this code may include:
- Engine stalls when the vehicle stops
- Engine light is on
- Service engine soon warning light is on
- Torque clutch converter is disabled
- Less fuel efficient
- Decreased engine performance, especially at higher speeds
- Transmission shift patterns are erratic
- Brake light does not illuminate
What Are Some Causes of a P0703 Code?
A P0703 can be caused by the following:
- Faulty or misadjusted brake switch
- Open or shorted brake switch harness
- Damaged connectors in the brake switch circuit
- Blown fuse
- Blown fusible link
- PCM failure
How Serious Is the P0703 Code?
A P0703 code is fairly serious and should be fixed as soon as possible. At the very least, it will only affect your brake light switch, which is a serious safety concern.
If the TCC is affected, then it could damage the transmission. Additionally, this may also cause your vehicle to suddenly stall and for the battery to die.
Can I Still Drive with a P0703 Code?
It is not recommended to drive with a P0703 code. Doing so can make the damage worse, especially to your battery and your TCC. It is best to bring your vehicle to a trusted professional as soon as possible.
How Easy Is It to Diagnose a P0703 Code?
If you are not experienced with this error code, then diagnosing it can be a problem. Many things can cause a P0703 code. Determining it will require a knowledge of your vehicle, as well as attention to detail. It is recommended to consult a professional to diagnose this error.
A professional will diagnose this code, beginning with the wiring, sockets, and fuse of the brake light circuit. The wiring and connectors of the PCM will also need to be inspected for shorted connectors and corrosion.
A test drive will determine if the code is not intermittent. If the code isn’t intermittent, then a professional will check the battery voltage of the brake light switch. At this point, if the cause is still not determined, the TCC will need to be checked by driving the vehicle at highway speeds.
How Difficult Is It to Inspect a P0703 Code?
You can try to inspect the brake light switch, circuit, fuse, sockets, and bulbs to determine if it is causing this error. However, this inspection requires attention to detail. If you are inexperienced, then it is recommended to bring your vehicle to a trusted professional.
If your fixes do not work, then more involved repairs may be necessary. The issues may lie with other systems. These include the PCM or even the TCC. If you are not familiar with these repairs, then it is recommended to have a trusted professional do the job for you.
Need Additional Help with Your P0703 Code?
A P0703 code is a serious code that requires urgent fixes. To make sure that your vehicle is repaired properly, check out trusted repair centers in your area.
To learn more about error codes, you can check out this OBD-II database.
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