EBS Tester for Truck & Trailers
aide automotive can report on a Rear Truck Brake Fault Solution!
DAF & Scania trucks fitted with Electronic Braking Systems (EBS) could have the same fault but for different reasons. The fault occurs after the vehicle has been driven for a few miles, when the rear brakes slowly start to apply by themselves and in some cases the brakes are on so much that the vehicle is un-drivable.
There are two reasons this fault can appear, the first one is quite simple. On the rear of the vehicle there is a EBS modulator valve which controls the brake pressure to the rear brakes, one of these pipes connected to this valve is from the redundancy valve. This is a saftey back up for the brakes, if in event the EBS fails the truck is left with some brakes to stop the vehicle.
If the redundancy valve starts to leak the air pressure can build up in the pipe connected to the rear modulator valve and start to apply the rear brakes, at the same time the EBS system which constantly monitors the brake pressure when you press the brake pedal sees that there is pressure in the modulator but knows the driver dosnt have his/her fott on the brake so assumes the rear modulator is faulty and puts the EBS warning light on in the cab.
This means there is two faults being caused by the one leaking valve, the EBS causedlight on and the rear brakes applying. The easiest way to identify this fault is by removing the pipe which comes from the redunacy valve when the brakes are on, you will hear the aire pressure being released from the pipe and hear the brake come off.
The Second reason this same fault can appear is a faulty foot brake valve. On a EB System when you press the foot brake on, the foot brake valve not only supplies air pressure to the rear modulator and applies the brakes, it also sends a CAN signal to the rear modulator to apply the brakes. The CAN signal is basically an electronic signal telling the rear modulator to apply the brakes. Inside the foot brake valveare switches which knowhow far you have pressed the pedal down, if these switch’s work incorrectly they can think you have pressed the pedal down when you havent and tell the rear modulator to apply the brakes.
The easiest way to see if the fott brake valve is causing the fault is by removing the electrical connection from the foot brake when the fault appearsand you will hear the brakes release. In both cases the rear brakes usually only apply a small amount but in both cases the EBS light will come on.
aide automotive offer products to test ABS or EBS Sensors or offer brake testers for inspection sheet brake testing.
Trailer testers are available in portable format of wrokshop / van monuted testers.