Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 78 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 3.8L)DIAGNOSTIC TESTSDTC P0719: TCC BRAKE SWITCH CIRCUIT - LOW INPUTDIAGNOSTIC PROCEDURES
1999 GMC Forward Control 5.7 R, Automatic
Diagnostic Procedures
1999 GMC Forward Control 5.7 R, AutomaticSECTION Diagnostic Procedures
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 Pontiac Grand Prix, 2002 Pontiac Bonneville, 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, and 2002 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
- Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing Diagnostic System Check - Engine Controls, go to next step.
- Install a scan tool. Turn on the ignition with the engine off. Record the Failure Records. Clear the DTCs. With a scan tool, observe the TCC BRAKE SWITCH parameter. Does the scan tool display CLOSED? If yes, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
- Remove the fuse from the ignition 1 voltage circuit. Inspect the fuse for an open. Replace the fuse if necessary. Was the fuse open? If yes, go to next step. If no, go to step 5.
- Test the ignition 1 voltage circuit (CKT 239) of the TCC brake switch for a short to ground between the fuse block and the brake switch. Test the signal circuit (CKT 420) of the TCC brake switch for a short to ground between the PCM and the TCC brake switch. Repair as necessary. After repairs, go to step 10.
- Disconnect the TCC brake switch 4-way connector. Connect a fused jumper wire from terminal "A" to terminal "B" of the TCC brake switch connector. Turn on the ignition with the engine off. With a scan tool, observe the TCC BRAKE SWITCH parameter. Does the scan tool display CLOSED? If yes, go to step 8. If no, go to next step.
- Test the ignition 1 voltage circuit (CKT 239) of the TCC brake switch for an open between the fuse block and the brake switch. Did you find and correct the condition? If yes, go to step 10. If no, go to next step.
- Test the signal circuit (CKT 420) of the TCC brake switch for an open between the PCM and the brake switch. Did you find and correct the condition? If yes, go to step 10. If no, go to step 9.
- Replace the TCC brake switch. After repairs, go to step 10.
- Replace PCM. Program replacement PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
- Perform the following procedure in order to verify the repair:
- Select DTC.
- Select CLEAR INFO.
- Turn on the ignition with the engine off.
- The TCC brake switch must be closed (pedal released) for more than 2 seconds.
- Select SPECIFIC DTC.
- Enter DTC P0719.
Has the test run and passed? If yes, system is okay. If no, go to step 1.
NOTE:
Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. Using the CLEAR INFO function will erase the stored Failure Records from the PCM.
NOTE:
The condition that affects this circuit may exist in other connecting branches of the circuit.
NOTE:
The condition that affects this circuit may exist in other connecting branches of the circuit.
CAUTION:
When you are performing service on or near the SIR components or the SIR wiring, you must disable the SIR system. See AIR BAG RESTRAINT SYSTEMS article in ACCESSORIES & EQUIPMENT. Failure to follow the correct procedure could cause air bag deployment, personal injury, or unnecessary SIR system repairs.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.