Freightliner chassis exhaust brake 2003

[islandvagabonds]

Hello all, my exhaust brake on my 2003 Discovery has been operating intermittently for the past year. Technicians have been challenged to remedy the problem. The exhaust valve is new 12 months ago and worked well for a while. Indicator lights on the dash show the brake is operational but the tranny does not down shift nor does the valve close on the exhaust. Does anyone know how to test the valve operation while parked?

thanks for all comments

bob

[mchero]

If the tranny is not downshifting its not the valve. Check the switch on the throttle assembly.

[Sierra_Valley_M]

I had a similar issue on a 1992 Monaco Dynasty. It was resolved by sending the ECU to Transmission Instruments in Texas. The power supply was rebuilt. Works perfectly now.

[wolfe10]

Get a wiring diagram from your chassis maker. The problem is likely in the dash area with the signal not getting to the Allison ECM. There are some relays involved-- one may be going out.