Exhaust Restrictor - Chevrolet T-Series Owner's Manual

Exhaust Restrictor

If your vehicle is equipped with this feature, there
is an exhaust restrictor valve located in the
exhaust stream. The valve closes to provide back
pressure to the engine for the purpose of
warming the engine quickly.
The exhaust restrictor operates:
•
while the engine is running.
•
while the vehicle is not moving.
•
while the accelerator, brake and clutch pedals
are not pressed on a manual transmission
vehicle.
•
while idling or driving in cold temperatures.
•
when the shift lever is in NEUTRAL (N)
or PARK (P) on an automatic transmission
vehicle.
On vehicles equipped with a diesel engine
exhaust brake, the exhaust brake switch must be
on. See Diesel Engine Exhaust Brake on
page 60 for more information. The indicator in the
exhaust brake switch will be lit when the exhaust
restrictor is active. The exhaust brake indicator
light in the center of the instrument panel will also
be lit whenever the exhaust restrictor is active.
See Exhaust Brake Indicator Light on page 114 for
more information.
When the engine coolant temperature is below
149°F (65°C) and the outside temperature is below
50°F (10°C), the exhaust restrictor will come on
within 45 seconds of starting the engine. After
running the engine for an additional 45 seconds,
the engine idle will increase.
The exhaust restrictor will shut off and engine idle
will return to normal once the engine is warmed
up, or the transmission is shifted into a drive gear.
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