4L80-E / 4L85-E Automatic Transmission
DTC P0719
Circuit Description with 4L80-E / 4L85-E Automatic Transmission
The torque converter clutch (TCC)/stop lamp switch indicates the brake pedal status. The normally closed TCC/stop lamp switch supplies a B+ signal to the powertrain control module (PCM). The signal voltage circuit opens when the brake pedal is applied.
If the PCM detects an open TCC/stop lamp switch circuit during accelerations, then DTC P0719 sets. DTC P0719 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0719 Brake Switch Circuit Low Voltage
Conditions for Running the DTC
No AT VSS DTC P0502 or P0503.
Conditions for Setting the DTC
^ All conditions are met for 8 occurrences.
^ The PCM detects an open TCC/stop lamp switch/circuit, 0 volts, for 15 minutes.
^ 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 1.7 seconds.
3. Then the vehicle speed is greater than 40 km/h (25 mph) for 7 seconds.
Action Taken When the DTC Sets
^ The PCM does not illuminate the malfunction indicator lamp (MIL).
^ For TCC scheduling, the PCM disregards the brake switch state if the throttle angle is greater than 1.5 percent and the vehicle speed is greater than 32 km/h (20 mph).
^ 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 clears the DTC from PCM history.
^ 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 the DTC passes.
Diagnostic Aids
Inspect the brake switch for proper mounting and operation.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
4. This step tests for TCC/stop lamp switch voltage to the PCM connector.
7. This step isolates the TCC/stop lamp switch as a source for setting the DTC.
10. This step tests for a short to ground in the brake fuse circuit.
12. This step tests for a short to ground in the TCC brake switch signal circuit, from the TCC/stop lamp switch to the PCM.
13. This step isolates the PCM as a source for causing the fuse to open.