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JAKE BRAKES
If your engine is equipped with both cruise
control and Jake Brake® retarders, the
Jakes can operate automatically while you
are in cruise control. If the cruise control/
engine brake function is turned on in the
ECM programming, the Jakes will come on
“low” when your set road speed increases a
few MPH or KPH above your set cruise speed.
If your speed continues to increase, the
ECM will increase the Jakes’ braking power
progressively. When the vehicle returns to
the set cruise speed, the Jakes will “turn off”
until the next time you need them. For safety
reasons, don’t use cruise control when it’s
not possible to keep the vehicle at constant
speed due to winding roads, heavy trafc,
slippery roads, or when descending grades
that call for Jake Brake® assistance.
SHIFTING
Depending on your transmission model, the
gear split may vary from 500 to 300 RPM.
The electronic governor provides almost no
overrun capability, and if the transmission
is downshifted too early, you will experience
a temporary loss of pulling power until the
engine speed falls below rated speed. This
is true even on steep grades with heavy
loads. When using an 18, 15 or 13 speed
transmission, you will need to downshift at an
RPM that allows “less than rated” RPM before
throttle application in the next gear down. You
may want to limit engine speed to 1900 RPM
in all gears. The Series 60 provides constant
horsepower from 1800 RPM through 2100
RPM, but fuel economy is not as efcient
above 1800 RPM and may cause premature
engine issues and/or failures.
If you decide to drive at lower RPM’s for
improved fuel economy, don’t let different
engine noises throw you off guard. The
Series 60 sounds quiet at 1400 RPM,
almost as if it had quit pulling. Don’t believe
it! if you had a boost gauge to look at while
driving, you would notice the turbocharger
maintaining steady intake manifold
pressure, even as RPM’s fall. Depending on
the air intake arrangement, you may also
experience a “chufng” sound as the engine
starts to pull hard at the lower RPM’s. This is
caused by the velocity changes of the airow
within the air intake plumbing. Electronic
engines can actually deliver more fuel at
lower engine speeds than rated speed.
IDLE REQUIREMENTS
If you have to idle your engine for any reason,
it is suggested that RPM’s be set at 900 to
1000 RPM. Try to minimize idle times as
much as possible for the rst 10,000 miles
on the engine. Lower idle RPM’s will cause
oil slubber, and can inhibit the cylinder
rings’ ability to seat properly.
IDLE SHUTDOWN
The DDEC engine may also have an
optional idle shutdown system. The
purpose of this system is to conserve fuel by
eliminating excessive idling and to allow for
a turbocharger cool down period. To activate
the shutdown, the transmission must be in
neutral with the vehicle parking brakes set and
with the engine in idle or fast idle mode. The
cruise control system may also be programmed
to permit fast idle using the cruise control
switches. With the engine at normal idle, the
transmission in neutral, and the service brake
on, turn on the cruise control “on/off” switch,
and use the “Resume” switch. The engine RPM
should increase to a predened RPM. The RPM
can be raised or lowered from this point using
the “set” and “resume” switches.
S-60 ENGINE DRIVING TIPS
