Circuit Description
The brake switch indicates the status of the brake pedal. The normally-closed brake switch supplies a B+ signal on the circuit 420 to the PCM. Applying the brake pedal opens the signal voltage circuit. The PCM de-energizes the TCC Solenoid Valve when the PCM receives the signal.
DTC P0719 detects an open brake switch during accelerations. DTC P0719 is a type A DTC.
Conditions for Setting the DTC
| • | No VSS DTC P0502 |
| • | The PCM detects an open brake switch/circuit (0 volts) for 15 minutes without going off for 2 seconds, and the following events occur seven consecutive times: |
| - | The vehicle speed is less than 8 km/h (5 mph); |
| - | Then the vehicle speed is between 8 and 32 km/h (5 and 20 mph) for 4 seconds; |
| - | Then the vehicle speed is greater than 32 km/h (20 mph) for 6 seconds. |
Action Taken When the DTC Sets
| • | The brake switch remains closed (12 volts) with the brake pedal released. |
| • | Inhibit engagement of the TCC Solenoid Valve |
| • | Inhibit 4th gear if in hot mode |
| • | The freeze shift adapts from being updated. |
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
Conditions for Clearing the DTC
| • | The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported. |
| • | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | 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
| • | Inspect the wiring for any poor electrical connections at the PCM. Inspect the wiring at the TCC brake switch. Look for the following conditions: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change. |
| • | Ask the customer about the customer's driving habits. Ask if the customer has any unusual driving conditions (e.g. stop-and-go, expressway, etc.). |
| • | Check for the most current calibration ID. Check for the latest bulletins. |
| • | Inspect the brake switch for proper mounting and adjustment. |
Test Description
The numbers below refer to the step numbers on the diagnostic chart.
-
This Step tests for voltage at the brake switch.
-
This Step verifies that the brake switch is functioning normally.
-
This Step verifies that circuit 420 is functioning normally at the PCM.
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 Freeze Frame and the Failure Records for reference. The Clear Info function will erase the data. When you apply the brake pedal, does the scan tool display the TCC Brake Switch as Applied; then as Released when you release the brake? | -- | Go to Diagnostic Aids | |||||||
Does the test lamp illuminate? | -- | |||||||||
4 |
Does the test lamp illuminate? | -- | ||||||||
5 | Repair the open condition in ignition feed circuit 339 to the brake switch. Refer to Electrical Diagnosis, Section 8A. If the ENG 1 fuse is open, examine circuit 420 for a short to ground. Is the repair complete? | -- | -- | |||||||
Apply the brake pedal. Is the test lamp OFF when you apply the brake pedal? | -- | |||||||||
7 | Inspect the brake switch for incorrect adjustment. Did you find and correct a problem? | -- | ||||||||
8 | Inspect circuit 420 for a short to B+. Did you find and correct a problem? | -- | ||||||||
Did the test lamp illuminate? | -- | |||||||||
10 | Replace the brake switch. Refer to Brake switch Replacement. Is the replacement complete? | -- | -- | |||||||
11 |
With the brake applied, does the scan tool display TCC Brake Switch as Applied, then Released with the brake pedal released? | -- | Go to Diagnostic Aids | |||||||
12 | Repair the open condition in circuit 420 from the TCC brake switch to the PCM. Refer to Electrical Diagnosis, Section 8A. Is the repair complete? | -- | -- | |||||||
13 |
Did you find and correct a problem? | -- | ||||||||
14 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming , Section 6. Is the replacement complete? | -- | -- | |||||||
15 |
Has the test run and passed? | -- | The repair is verified, exit the DTC table. |
