P0719: Brake Switch Circuit Low Input

What Does Code P0719 Mean?

Even though this is a brake switch problem, it is directly related to transmission operation. The brake switch shows if the brake pedal is depressed to the Powertrain Control Module (PCM). The brake switch is a normally closed contact switch that supplies battery voltage (12 volts) on the circuit to the PCM. Applying the brake pedal opens the contacts in the switch interrupting voltage to the computer. When the brake pedal is released, the ECM receives a constant 12 volt signal. If the PCM receives zero a volt signal at the brake switch input terminal, and the torque converter clutch (TCC) is engaged, it will de-energize the TCC solenoid valve. The PCM does not look at the brake switch input for TCC apply if there is any brake switch circuit fault.

How Code P0719 Is Set

When the PCM or ECM detects an open brake switch circuit- 0 volts= low input during acceleration, then code P0719 is stored.

Code P0719 Symptoms

• Check engine light
• Brake lights not working
• No TCC engage or release
• No overdrive gear

Common Causes of P0719

• Faulty brake switch
• Open or shorted brake switch harness
• Poor electrical connection
• Misadjusted brake switch

How to Diagnose P0719

Depending on the make, model and year of your vehicle, diagnosis can be very different. The reason is that on older vehicles the brake switch is just on on / off switch as described above. On newer cars and trucks it is a variable resistor. This is because brake switch apply information is used for more then just brake lights and transmission data. It will be used for cruise contol operation, shifter lock release, airbag systems, ABS, automatic brake assist functions etc. For the older type switch it is simple to diagnose. Just use a test light to check for power in, then power out when the brake pedal is applied.

For newer vehicles a volt / ohm meter is required to test for variable resistance values. You would set the meter on ohms, put the leads on the correct in and out of the switch, depress the brake pedal and watch for the resistance value to change smoothly. A faulty switch would either not read at all, or in the case of this code P0719 the reading would jump around or go up and down or even blank out as you are pressing the pedal. Sometimes an intermittant signal is hard to catch this way because a digital meter changes very rapidly. An older style analog meter with a needle is actually a better diagnostic tool in this case.