p0179
#1
05-27-2010, 05:47 PM
p0179
can someone explain what code p0719 is? It shows up generic Brake switch B circuit low input. it always shows up 2 codes at the same time. when i first bought the 97 bravada it showed up every now and again. it's now shown up 3 times in 2 days. any help troubleshooting this or explaining it would be appreciated...there was only one thread that mentioned it in search and it didn't really touch on it. thanks. it's one of the few codes that is not listed in the obd 2 code index on the site thanks!
Last edited by Jason Rebellion; 05-27-2010 at 09:20 PM. Reason: fixed the code
#4
05-28-2010, 06:34 AM
Here ya go:
DTC P0719: BRAKE SWITCH CIRCUIT LOW INPUT (SWITCH STUCK ON)
Circuit Description
Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. PCM deenergizes TCC solenoid when brake pedal is applied. DTC P0719 is set if PCM detects an open (stuck on) brake switch during acceleration.
Conditions For Setting DTC P0719
DTC will set under the following conditions:
• DTCs P0502 or P0503 (vehicle speed sensor) are not present.
• Vehicle speed is less than 5 MPH.
• Then vehicle speed is 5-20 MPH for 4 seconds, then vehicle speed is more than 20 MPH for 6 seconds.
• All conditions must occur 7 times with brake switch on for more than 15 minutes without PCM detecting voltage input of 2 seconds or more.
Action Taken By PCM
PCM performs the following if DTC is set:
• Will light MIL after first failure signal.
• Ensures TCC brake switch remains closed with brake pedal released.
• Inhibits TCC engagement.
• Inhibits 4th gear if in hot mode.
• Freezes shift adapts from being updated.
• DTC P0719 is stored in PCM history.
Diagnostic Procedure
1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Apply and release brake pedal while observing scan tool. If scan tool displays brake pedal in correct positions, see DIAGNOSTIC AIDS. If scan tool does not display brake pedal in correct positions, go to next step.
3. Connect test light between ground and ignition feed circuit terminal at brake switch. If test light is off, repair open in ignition feed circuit, then go to step 9). If test light is on, connect test light between ground and brake switch signal terminal at brake switch. If test light is off, go to step 5). If test light is on, go to next step.
4. Apply brake pedal. If test light is off, go to step 6). If test light is on, check brake switch signal circuit for short to voltage. Repair circuit as necessary, then go to step 9). If circuit is okay, go to next step.
5. Ensure brake switch assembly is adjusted properly. Adjust brake switch as necessary, then go to step 9). If adjustment is okay, replace brake switch, then go to step 9).
6. Release brake pedal. Turn ignition off. Disconnect appropriate PCM connector connected to brake switch signal circuit. See WIRING DIAGRAMS . Turn ignition switch to ON position. DO NOT start engine. Connect test light between ground and brake switch signal terminal of appropriate PCM connector. If test light is on, go to next step. If test light is off, check for open in brake switch signal circuit between brake switch and PCM. Repair as necessary, then go to step 9).
7. Turn ignition off. Reconnect appropriate PCM connector. Turn ignition switch to ON position. DO NOT start engine. Apply and release brake pedal. If scan tool displays brake pedal in correct positions, see DIAGNOSTIC AIDS. If scan tool does not display brake pedal in correct positions, go to next step.
8. Check PCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM, then go to next step.
9. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0719". Ensure TCC brake switch signal indicates zero volts for 2 seconds with brake pedal applied. If DTC P0719 is not present, repair is complete. If DTC P0719 is still present, repeat test.
Diagnostic Aids
Check TCC brake switch for proper adjustment.
Check PCM calibration for current update.
Inspect wiring for poor connections at PCM.
Check for bent, backed out, deformed or damaged terminals.
Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring.
Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.
Circuit Description
Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. PCM deenergizes TCC solenoid when brake pedal is applied. DTC P0719 is set if PCM detects an open (stuck on) brake switch during acceleration.
Conditions For Setting DTC P0719
DTC will set under the following conditions:
• DTCs P0502 or P0503 (vehicle speed sensor) are not present.
• Vehicle speed is less than 5 MPH.
• Then vehicle speed is 5-20 MPH for 4 seconds, then vehicle speed is more than 20 MPH for 6 seconds.
• All conditions must occur 7 times with brake switch on for more than 15 minutes without PCM detecting voltage input of 2 seconds or more.
Action Taken By PCM
PCM performs the following if DTC is set:
• Will light MIL after first failure signal.
• Ensures TCC brake switch remains closed with brake pedal released.
• Inhibits TCC engagement.
• Inhibits 4th gear if in hot mode.
• Freezes shift adapts from being updated.
• DTC P0719 is stored in PCM history.
Diagnostic Procedure
1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Apply and release brake pedal while observing scan tool. If scan tool displays brake pedal in correct positions, see DIAGNOSTIC AIDS. If scan tool does not display brake pedal in correct positions, go to next step.
3. Connect test light between ground and ignition feed circuit terminal at brake switch. If test light is off, repair open in ignition feed circuit, then go to step 9). If test light is on, connect test light between ground and brake switch signal terminal at brake switch. If test light is off, go to step 5). If test light is on, go to next step.
4. Apply brake pedal. If test light is off, go to step 6). If test light is on, check brake switch signal circuit for short to voltage. Repair circuit as necessary, then go to step 9). If circuit is okay, go to next step.
5. Ensure brake switch assembly is adjusted properly. Adjust brake switch as necessary, then go to step 9). If adjustment is okay, replace brake switch, then go to step 9).
6. Release brake pedal. Turn ignition off. Disconnect appropriate PCM connector connected to brake switch signal circuit. See WIRING DIAGRAMS . Turn ignition switch to ON position. DO NOT start engine. Connect test light between ground and brake switch signal terminal of appropriate PCM connector. If test light is on, go to next step. If test light is off, check for open in brake switch signal circuit between brake switch and PCM. Repair as necessary, then go to step 9).
7. Turn ignition off. Reconnect appropriate PCM connector. Turn ignition switch to ON position. DO NOT start engine. Apply and release brake pedal. If scan tool displays brake pedal in correct positions, see DIAGNOSTIC AIDS. If scan tool does not display brake pedal in correct positions, go to next step.
8. Check PCM connector for damaged or backed out connector terminals, weak terminal tension and poor connections. Repair as necessary, then go to next step. If terminals and connections are okay, replace PCM, then go to next step.
9. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0719". Ensure TCC brake switch signal indicates zero volts for 2 seconds with brake pedal applied. If DTC P0719 is not present, repair is complete. If DTC P0719 is still present, repeat test.
Diagnostic Aids
Check TCC brake switch for proper adjustment.
Check PCM calibration for current update.
Inspect wiring for poor connections at PCM.
Check for bent, backed out, deformed or damaged terminals.
Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring.
Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.
