Warning and Indicator Lights
High-Beam Indicator (blue) Indicates the headlights are on high beam.
Low Air Pressure Warning Lamp
(red)
Activates with a buzzer when air pressure in the primary or
secondary air reservoir falls below 64 to 76 psi (440 to 525
kPa).
High Coolant Temperature Warning
Lamp (red)
Activates with a buzzer when the coolant temperature goes
above a maximum level specified by the engine
manufacturer (see the engine manual).
Low Engine Oil Pressure Warning
Lamp (red)
Activates with a buzzer when engine oil pressure goes below
a minimum level specified by the engine manufacturer (see
the engine manual).
BRAKE
Parking/Emergency Brake Lamp
(BRAKE!) (red)
Indicates the parking brake is engaged, or hydraulic brake
fluid pressure is low. A buzzer activates when the vehicle is
moving over 2 mph (3 km/h) with the parking brake set.
Fasten Seat Belt Warning Lamp
(red)
Illuminates for 15 seconds when the ignition key is turned to
the ON position.
Intake Heater Warning Lamp
(amber)
Indicates the intake air heater is active.
Water in Fuel Warning Lamp
(amber)
Indicates that the fuel could contain water.
Low Battery Voltage Warning Lamp
(red)
Indicates battery voltage is 11.9 volts or less.
NO
CHARGE
No Charge Warning Lamp (amber) Indicates an alternator charge output failure.
Instrumentation Control Unit 4
(ICU4 and ICU4-2)
The ICU4 and ICU4-2 instrument clusters are
individual-gauge clusters, with intelligent lightbars
(ILB) and integrated warning and indicator lights. See
Fig. 2.2 for a typical layout of the gauges. The ICU4
is on vehicles with engines that were manufactured
up until December 31, 2006, and the ICU4-2 is on
vehicles with engines that were manufactured Janu-
ary 1, 2007 or later, that are EPA07 compliant. They
can be differentiated by the ISO icons on the ICU4-2.
See Fig. 2.3 and Fig. 2.4. Also, on the ICU4, the
message display shows voltmeter readings.
Standard gauges are:
•
speedometer
•
engine coolant temperature
•
engine oil pressure
•
battery voltmeter
•
fuel level
Gauges with a warning light on the gauge are listed
below, with an indication of how the warning light is
activated:
•
engine coolant temperature (high)
•
engine oil pressure (low)
Instruments and Controls Identification
2.3
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