4T40-E / 4T45-E Automatic Transaxle

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

Circuit Description with 4T40-E / 4T45-E Automatic Transaxle
The brake switch indicates brake pedal status to the PCM. The normally-closed brake switch supplies battery voltage to the PCM. Applying the brake pedal opens the switch, interrupting voltage to the PCM. Releasing the brake pedal resumes voltage to the PCM. When the PCM senses 0 volts at the brake switch input, the PCM de-energizes the Torque Converter Clutch (TCC) solenoid valve. The PCM disregards the brake switch input for TCC scheduling if there is a brake switch circuit fault (Refer to Diagnostic Aids).

When the PCM detects an open brake switch (stuck ON) during accelerations, then DTC P0719 sets. DTC P0719 is a type C DTC.

CONDITIONS FOR RUNNING THE DTC
^ The ignition switch is in the ON position.
^ The system voltage is 8-18 volts.

CONDITIONS FOR SETTING THE DTC
DTC P0719 sets if the PCM detects an open brake switch or circuit (0 volts) for 15 minutes and the following conditions occur eight times:
^ The vehicle speed is less than 8 km/h (5 mph);
^ then, the vehicle speed is 8-32 km/h (5-20 mph) for 3 seconds;
^ then, the vehicle speed is greater than 32 km/h (20 mph) for 6 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM does not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
^ The PCM stores DTC P0719 in PCM history.

CONDITIONS FOR CLEARING THE DTC
^ A scan tool can clear the DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS
^ If the PCM detects a brake switch circuit fault, then the brake switch input is disregarded for TCC scheduling. The PCM then uses throttle position and vehicle speed inputs to determine TCC application and release. Use of these inputs may result in a noticeable harsh apply or abrupt release of the TCC.
^ Ask about the customer's driving habits. Ask about unusual traffic conditions, and stop-and-go driving.
^ Inspect the brake switch for proper adjustment.
^ Inspect the connectors at the PCM, the brake switch and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent and Poor Connections in Diagrams.
^ Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Diagrams.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. Disconnecting the brake switch connector, jumping the circuit, and observing a status change, isolates the brake switch as the source of the DTC.
3. If the power feed circuit shorts to ground, the ERLS fuse opens.
5. If the brake switch is properly adjusted, then the brake switch must be replaced.
8. Replace the PCM only after you have completed the preceding diagnostic steps.