The stop lamp switch indicates brake pedal status to the transmission control module (TCM). The normally-open stop lamp switch supplies ignition voltage to the TCM. Applying the brake pedal closes the switch, supplying voltage to the TCM. Releasing the brake pedal interrupts voltage to the TCM. When the TCM senses ignition voltage at the stop lamp switch input, the TCM de-energizes the torque converter clutch (TCC) solenoid valve.
When the TCM detects an open stop lamp switch, stuck OFF, during decelerations, DTC P0719 sets. DTC P0719 is a type C DTC.
This diagnostic procedure supports the following DTC:
DTC P0719 Brake Switch Circuit Low Voltage
• | No VSS DTCs P0722 or P0723. |
• | DTC P0719 has not passed this ignition cycle. |
DTC P0719 sets if the TCM detects an open stop lamp switch, 0 volts, during vehicle deceleration and the following conditions occur 8 times:
• | The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL). |
• | The TCM disregards the stop lamp switch input for TCC scheduling. The TCM 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. |
• | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records. |
• | The TCM stores DTC P0719 in TCM history. |
• | A scan tool can clear the DTC. |
• | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring. |
• | The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes. |
The numbers below refer to the step numbers on the diagnostic table.
Disconnecting the stop lamp switch connector, jumping the circuit, and observing a status change, isolates the stop lamp switch as the source of the DTC.
If the ignition 1 voltage circuit shorts to ground, the BRAKE fuse opens.
If the stop lamp switch is properly adjusted, then the stop lamp switch must be replaced.
Replace the TCM only after you have completed the preceding diagnostic steps.
Step | Action | Yes | No | ||||||
---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |||||||
Important: Before clearing the DTC, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the TCM. Did the Brake Switch status change from Open to Closed? | Go to Step 5 | Go to Step 3 | |||||||
Is the fuse open? | Go to Step 4 | Go to Step 6 | |||||||
4 |
Important: The condition that affects this circuit may exist in other connecting branches of the circuit. Refer to Power Distribution Schematics for complete circuit distribution. Test the ignition 1 voltage circuit of the stop lamp switch for a short to a ground. Refer to Testing for Short to Ground and Wiring Repairs . Did you find and correct the condition? | Go to Step 9 | -- | ||||||
Did the stop lamp switch require adjustment? | Go to Step 9 | Go to Step 7 | |||||||
6 |
Refer to Testing for Continuity and Wiring Repairs . Did you find and correct a condition? | Go to Step 9 | Go to Step 8 | ||||||
7 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement . Did you complete the replacement? | Go to Step 9 | -- | ||||||
Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | -- | |||||||
9 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Go to Step 10 | Go to Step 2 | ||||||
10 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | System OK |