Community Forums

gstone · 06-25-2013, 09:22 AM

I have a 2008 Alegro Fred powered with an ISB. I am having problems with the exhaust brake. With the exhaust brake switch on, when I back off the throttle the exhaust brake comes on as it should. However, when I accelerate, the exhaust brake stays on and will not allow acceleration, with the check engine light coming on. The only way to clear it is to turn the exhaust brake switch off, and after about 30 seconds the exhaust brake goes off and I am able to accelerate as normal. No problem if I leave the exhaust brake off. Any suggestions?

csrrsr · 06-25-2013, 10:12 AM

Sounds like your exhaust brake is sticking and needs to be cleaned. The tell all in your thread is when you turned it off and it took 30 seconds for the trap door to let loose and open up.

Skip426 · 06-25-2013, 10:33 AM

You have to know for certain if you have an external exhaust brake or if your braking is a function of the variable turbo vanes, this info should be in your engine owners manual . I'm not certain what year Cummins made the switch.

If you have the external exhaust brake , the control is an air solenoid, that has 2 functions, 1 allow air pressure to the actuator to close the flap in the exhaust pipe , and 2 vent the air pressure from the actuator, to allow the internal spring in the actuator to open the flap in the exhaust pipe to allow normal engine operation. If lubing the mechanism doesn't help the operation, check the ground wiring on the air solenoid if all ok then you may need a new solenoid.