Fault code P0724 is called “Torque Converter/Brake Switch “B” Circuit High” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P0724
Diagnostic Code P0724 is set when the transmission control module (PCM) has detected a high signal level in a particular torque converter circuit. This code applies only to vehicles equipped with an automatic transmission.
Most vehicles equipped with OBD-II are controlled by a transmission controller that is integrated into the PCM. Other vehicles use a stand-alone transmission control module. This communicates with the PCM and other controllers through the Controller Area Network (CAN).
A torque converter is a type of hydraulic clutch that links the engine to the transmission. When the vehicle is in motion, the torque converter allows torque to be transferred to the transmission input shaft. When the vehicle is stopped, the torque converter absorbs engine torque using a sophisticated wet clutch system. This allows the engine to idle without stopping.
In lockup mode, the torque converter clutch (TCC) is gradually restricted. These gradual clutch restrictions are called torque converter lockup percentages. The working system contributes to fuel economy and optimum engine performance.
The torque converter lockup must be disengaged before engine RPMs drop to a certain level. And definitely before the vehicle has stopped idling. Otherwise, the engine will undoubtedly stall.
One of the specific signals the PCM uses to disengage the torque converter lockup is when the brake pedal is depressed. When the brake pedal is depressed, the brake lever causes the contacts in the brake switch to close. Closing one or more circuits.
When these circuits close, the brake lights come on. A signal is then sent to the PCM. This signal tells the PCM that the brake pedal is depressed and the torque converter lockup solenoid must be disengaged. Code P0724 refers to a high signal level in one of these brake switch circuits.
Symptoms of vehicle malfunctions
The main signal that an error P0724 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- Check engine control lamp on the control panel will light up (the code will be recorded in the memory as a malfunction).
- The torque converter clutch (TCC) does not work.
- The brake lights are not illuminated.
- Transmission is stuck in gear.
- Hard gear shifting.
- Reduced engine power.
- Increased fuel consumption.
- Problems with engagement and disengagement of torque converter lockup clutch.
Error P0724 is quite serious, as internal transmission damage can occur if the TCC lockup does not work for an extended period of time. Most models are designed so that the PCM will disable the TCC lockup when this code occurs. And will put the transmission control system into an emergency operation mode.
Factors that can cause this error code
The error code P0724 can mean that one or more of the following problems have occurred:
- Defective brake switch.
- Incorrectly adjusted brake switch.
- Brake switch wiring harness is broken or short-circuited.
- Poor electrical connection in brake switch circuit.
- Fuse blown or fusible link blown.
- In rare cases, PCM or TCM malfunction.
How to fix or reset OBD-2 code P0724
Some suggested steps for troubleshooting and fix the error code P0724:
- Check the fuses in the system with the brake pedal depressed.
- Inspect the connectors as well as the wiring.
- Check to see if the brake pedal brake light works. If the brake lights do not work, replace or adjust the brake switch.
- If necessary, flash or replace the PCM/TCM.
Diagnose and repair of problems
Before you begin the process of troubleshooting P0724, you should research the technical service bulletins (TSB) for your particular vehicle. In some cases, this can save a lot of time by pointing you in the right direction.
You should then perform a detailed visual inspection to check the condition of the wiring for obvious defects. Check the connectors and wiring to the brake switch as well as the PCM or TCM.
Normal readings for wiring and connections should be 0 ohms of resistance. The wiring continuity check should always be done with power disconnected from the circuit. To avoid short-circuiting and creating additional damage.
Resistance or lack of continuity indicates faulty wiring that is open or shorted. In this case, repair or replacement will be required.
If the voltage as well as the resistance in all circuits is within normal limits. The transmission control module may have failed and need to be replaced. PCM failures are relatively rare, but they do occur. Keep in mind that after replacing it, reprogramming must be done.
On which vehicles does this problem occur most frequently
Fault code P0724 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- Cadillac (Escalade)
- Chevrolet
- Dodge (Caravan)
- Ford
- Honda
- Mazda
- Mercedes-Benz
- Nissan
- Subaru (Forester)
- Toyota (Avensis, Camry, Corolla, Prado)
- Volkswagen
- GAZelle
Fault code P0724 can sometimes be found with other errors. The most common are the following: P0573, P0703, P0719, P0733, P1790.
