Circuit Description
The brake switch indicates brake pedal status to the powertrain control module (PCM). The brake switch is a normally-closed switch that supplies battery voltage on circuit 420 to the PCM. Applying the brake pedal opens the switch, interrupting voltage to the PCM. When the brake pedal is released, the PCM receives a constant voltage signal. If the PCM receives a zero voltage signal at the brake switch input, and the torque converter clutch (TCC) is engaged, the PCM de-energizes the 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 (pedal applied) during a number of accelerations, then DTC P0719 sets. DTC P0719 is a type D DTC.
Conditions for Running the DTC
| • | No VSS DTCs P0502 or P0503. |
| • | The vehicle speed is less than 8 km/h (5 mph). |
| • | Accelerate the vehicle to 32 km/h (20 mph) taking 4 seconds or more. |
| • | The vehicle speed remains above 32 km/h (20 mph) for 6 seconds or more. |
Conditions for Setting the DTC
DTC P0719 sets if:
| • | The brake switch remains open (no voltage to the PCM) for at least 15 minutes. |
| • | During 7 consecutive times that the conditions for running the DTC are met, the brake switch does not close for 2 seconds. |
Action Taken When the DTC Sets
| • | The PCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM disregards the brake switch for TCC scheduling when all of the following conditions are met: |
| - | The throttle position is greater than 6%. |
| - | The vehicle speed is greater than 59 km/h (37 mph). |
| - | The throttle position was previously greater than 12%, while the vehicle speed was greater than 67 km/h (42 mph). |
| - | The brake switch has not been OFF for more than 2 seconds during this ignition cycle. |
Conditions for Clearing the DTC
| • | A scan tool clears the DTC from PCM history. |
| • | The PCM clears the DTC from the PCM history if the vehicle completes 40 consecutive 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 ignition is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | If the PCM detects a brake switch fault, then the brake switch input is disregarded for TCC scheduling. The PCM then uses throttle position and vehicle speed input to determine TCC application and release. Use of these inputs may result in a noticeable harsh apply or abrupt release of the TCC. |
| • | Ensure that the brake switch is properly adjusted. |
| • | Inspect the wiring at the PCM, the brake switch connector and all other circuit connecting points for the following conditions: |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Reduced terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
2 |
Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records. Were the Failure Records recorded? | -- | -- | |||||
3 | Inspect the Eng. Emis. fuse for an open. Refer to Wiring Repairs in Wiring Systems. Was a condition found and corrected? | -- | ||||||
4 |
Important:: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Fuse Block Schematics in Wiring Systems, for complete circuit distribution. Inspect circuits 339 (PNK) and 420 (PPL) for a short to ground. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | Go to Diagnostic Aids | |||||
Does the brake switch status change from Open to Closed? | -- | |||||||
6 | Replace the brake switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes. Is the replacement complete? | -- | -- | |||||
7 | Inspect circuits 339 (PNK) and 420 (PPL) for an open. Refer to General Electrical Diagnosis in Wiring Systems. Was a condition found? | -- | ||||||
8 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||
9 | Repair the wiring as needed. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||
10 | Perform the following in order to verify the repair:
Has the test run and passed? | -- | System OK |
