4L80-E / 4L85-E Automatic Transmission

Diagnostic Chart (Part 1 Of 3):

Diagnostic Chart (Part 2 Of 3):

Diagnostic Chart (Part 3 Of 3):

Schematic:

CIRCUIT DESCRIPTION
The TCC/Stoplamp switch indicates the brake pedal status. The normally-closed TCC/Stoplamp switch supplies a B+ signal to the Vehicle Control Module (VCM). The signal voltage circuit opens when the brakes are applied.

If the VCM detects an open TCC/Stoplamp switch circuit during accelerations, then DTC P0719 sets. DTC P0719 is a type C DTC.

CONDITIONS FOR RUNNING THE DTC
^ No OSS DTC P0502 or P0503.
^ The following sequence of events occurs:
1. The vehicle speed is less than 8 km/h (5 mph).
2. Then the vehicle speed is 8-40 km/h (5-25 mph) for 3.5 seconds.
3. Then the vehicle speed is greater than 40 km/h (25 mph) for 6 seconds.

CONDITIONS FOR SETTING THE DTC
^ All conditions are met for 8 occurrence.
^ The VCM detects an open TCC/Stoplamp switch/circuit (0 volts) for 15 minutes.

ACTION TAKEN WHEN THE DTC SETS
^ The VCM does not illuminate the Malfunction Indicator Lamp (MIL).
^ For TCC scheduling, the VCM disregards the brake switch state if the TP sensor is greater than 1% and the vehicle speed is greater than 20 MPH.
^ The VCM records the operating conditions when the Conditions for Setting the DTC are met. The VCM stores this information as Failure Records.
^ The VCM stores DTC P0719 in VCM history.

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

DIAGNOSTIC AIDS
^ First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset.
^ Ask about the customer's driving habits and any unusual driving conditions he or she might have, such as stop and go traffic or expressway driving.
^ Inspect the brake switch for proper mounting and adjustment.
^ Inspect for the most current calibration ID and the latest bulletins.
^ Inspect the connectors at the VCM, the TCC/Stoplamp 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.
4. This step tests for TCC/Stoplamp switch voltage to the VCM connector.
7. This step isolates the TCC/Stoplamp switch as a source for setting the DTC.
10. This step tests for a short to ground in circuit 441 (ignition voltage) to the TCC/Stoplamp switch.
12. This step tests for a short to ground in circuit 420, from the TCC/Stoplamp switch to the VCM.
13. This step isolates the VCM as a source for causing the fuse to open.