1. Faulty vacuum pump: The vacuum pump is responsible for generating the vacuum that operates the exhaust brakes. If the vacuum pump is not working properly, the brakes will not engage when activated.
2. Leaking vacuum lines: The vacuum lines that connect the vacuum pump to the exhaust brake actuator can develop leaks over time. These leaks will cause the vacuum to be lost, preventing the brakes from engaging.
3. Faulty exhaust brake actuator: The exhaust brake actuator is the component that opens and closes the exhaust valves to create the braking effect. If the actuator is faulty, it will not be able to open and close the valves properly, preventing the brakes from working.
4. Faulty electrical switch: The exhaust brake switch is located on the gas pedal and is used to activate the brakes. If the switch is faulty, it will not be able to send the signal to the vacuum pump to engage the brakes.
Troubleshooting steps:
1. Check the vacuum pump: To check the vacuum pump, connect a vacuum gauge to the vacuum line that connects to the exhaust brake actuator. Start the engine and observe the vacuum gauge. If the vacuum is below 10 inches of mercury (inHg), the vacuum pump is not working properly and will need to be replaced.
2. Check the vacuum lines: Inspect the vacuum lines for any cracks, kinks, or disconnections. Replace any damaged or leaking vacuum lines.
3. Check the exhaust brake actuator: To check the exhaust brake actuator, remove the vacuum line from the actuator and apply vacuum directly to the actuator. If the actuator does not open and close properly, it is faulty and will need to be replaced.
4. Check the electrical switch: To check the exhaust brake switch, disconnect the electrical connector from the switch and use a multimeter to test for continuity between the terminals. If there is no continuity, the switch is faulty and will need to be replaced.
If you are not comfortable performing these checks, you should have the vehicle inspected by a qualified mechanic.
