Exhaust Braking Systems
Exhaust Brake Switch
The optional exhaust brake is controlled by a dash-
mounted rocker switch to help slow the vehicle when
the accelerator is released.
To turn the exhaust brake on, press on the upper
part of the rocker (at the light inside the switch). The
exhaust brake turns off automatically. See
or
When the exhaust brake switch is on, an amber LED
illuminates inside the switch. When the panel lights
are on, the EXHST BRK legend is backlit in green.
Mercedes-Benz Exhaust Brake
An exhaust brake is an optional auxiliary braking sys-
tem that assists but does not replace the service
brake system. The exhaust brake can be used alone
or together with the constant-throttle valves for steep
or long grades. The exhaust brake switch located on
the control panel, in combination with the accelerator
and clutch pedals, allows the driver to make maxi-
mum use of the exhaust brake in off-highway and
mountain driving as well as in traffic or high-speed
highway driving.
When only the exhaust brake is installed, a two-
position switch on the dash controls the engine brak-
ing system. The exhaust brake is only active when
the engine speed is between 1100 and 2700 rpm.
Depressing the accelerator or clutch pedal deacti-
vates the exhaust brake. The ABS system, when ac-
tive, also deactivates the exhaust brake.
The exhaust brake is a butterfly valve mounted in the
exhaust pipe. When the driver’s foot is not on the
accelerator pedal and the upper half of the exhaust
brake switch is pressed in, with the amber light on
the switch illuminated, an air cylinder shuts the but-
terfly valve, which restricts the flow of exhaust gases
and retards the engine. This retarding action is car-
ried through the engine and drivetrain, slowing the
vehicle and reducing the need for frequent service
brake applications.
Exhaust brakes are not intended for use as the pri-
mary braking system during vehicle operation.
Operating Characteristics
WARNING
Do not use the exhaust brake when driving on
slippery or low-traction road surfaces. Failure to
follow this precaution could result in a loss of
vehicle control and possible personal injury or
property damage.
Before starting the engine, make sure that the lower
half of the exhaust brake switch is pressed in and
the amber light is not illuminated. Do not turn the ex-
haust brake on until the engine has reached normal
operating temperatures.
When you remove your feet from both the accelera-
tor and clutch pedals and the upper half of the ex-
haust brake switch is pressed in with the amber light
illuminated, the exhaust brake is applied. The follow-
ing conditions should exist if the brake is operating
properly:
•
A slight change in the sound of the engine may
be noticed when the exhaust brake is applied.
•
Exhaust smoke should appear normal.
•
Engine temperature should remain in the nor-
mal operating range.
f610589
11/28/2001
Fig. 7.19, Exhaust Brake Switch
f610589a
03/31/2009
Fig. 7.20, Exhaust Brake Switch
Engines
7.15
