What are the causes of exhaust brake control circuit failure?
2 Answers
The causes of exhaust brake control circuit failure are damage to the exhaust pipe hardware, low air pressure in the vehicle, or jamming of the butterfly valve and faults in the exhaust pipe. Damage to the exhaust pipe hardware: For example, fracture of the bracket plate, breakage of the cylinder push rod, detachment of the bracket plate connecting bolts, or fracture of the bracket shaft. Vehicle air pressure below 0.8MPa: Air leakage at the cylinder intake joint or pipeline, or a faulty air source preventing the cylinder from receiving air supply. Butterfly valve jamming fault: The butterfly valve is stuck and cannot close properly. Exhaust pipe failure: Air leakage from the exhaust pipe cylinder or wobbling of the exhaust pipe butterfly valve. Inspection method: Before replacing the exhaust pipe, use a simple testing tool to connect the vehicle's air source to the exhaust butterfly valve. Test by turning the air on and off to confirm whether the exhaust butterfly valve can open and close normally. If it functions normally, the issue is not with the exhaust pipe; otherwise, replace the exhaust pipe.
There are quite a few reasons for exhaust brake control circuit failures. I've been driving trucks for over a decade, and the most common issue I've encountered is aging and cracked wiring, especially in the high-temperature environment of the engine compartment where the insulation tends to become brittle and split, leading to short circuits or open circuits. Another frequent problem is loose connectors—after driving on bumpy roads for a long time, the connectors can come loose, causing poor contact and functional failure. Relay failures are also common; if the contacts get burnt out, the signal won't transmit. When modifying audio systems or installing additional equipment, if the main wiring harness is tampered with, the circuit load might become too high and blow a fuse. Once, I had an issue where the solenoid valve connector got corroded due to water ingress, and when I opened it up, the pins were covered in green patina. These failures can be dangerous—exhaust brakes are crucial for slowing down on long descents, so getting it repaired ASAP is a must.
