2009 Mack Granite Series (GU) Operator's Manual
About This Handbook
This handbook is referred to as the Mack GraniteTM GU Series Operator’s Handbook. It covers all Mack GraniteTM GU models. Its identification number is TS920. Keep this handbook with the vehicle at all times to ensure that each owner and/or operator will have access to all pertinent information relating to the operation and handling of this vehicle.
INSTRUMENT PANEL
Tell-Tales
A tell-tale is a display that indicates the actuation of a device, a correct or defective condition, or a failure to function. The operator should become familiar with these symbols in order to recognize and react (if necessary) to the indicated condition. Tell-tale symbols are shown in the instrument panel illustrations on the following pages.
Colors
To promote visual recognition internationally, specific colors for tell-tales have been established. Unless governmental regulations (in the area where the vehicle is to be used) or engineering directives specify otherwise, the standard colors are:
- Blue – high-beam headlights/engine maintenance
- Flashing Green – turn signals
- Flashing Red – hazard condition involving the safety of personnel
- Steady Green – system in operation
- Steady Red – warning, immediate action required
- Amber – early warning, such as low fuel or Anti-Lock Brake System (ABS) malfunction
BASIC DISPLAY
The Basic Display is an in-dash computer that allows the vehicle operator to monitor a minimum amount of information supplied by the V-MAC IV electronic control system. The operator presses a push button located directly below the driver information display to retrieve information.
Trailer Anti-Lock Brake System (ABS) Indicator (Amber) – Indicates an ABS malfunction. If the light turns on and stays on, a malfunction is indicated. For additional information on operating an ABS-equipped vehicle, refer to “Anti-Lock Brake System (ABS)” page 157, of the OPERATION section.

HEST Indicator (Amber) (If Equipped) The High Exhaust Temperature (HEST) indicator is displayed when the exhaust temperature reaches 300 C (572 F) and the regeneration process begins. When the regeneration process is completed, the engine should be allowed to run until the HEST indicator shuts off.
During an automatic regeneration while the vehicle is moving, the HEST indicator will only illuminate during regeneration when vehicle speed is less than 8 kph (5 mph). During a parked regeneration, the HEST indicator will turn off when regeneration is complete and the exhaust temperature has returned to a normal temperature.
Secondary Air Pressure Gauge Indicates the air pressure
in the air brake system(s). The normal operating air pressure is between 759 kPa (110 psi) and 897 kPa (130 psi) in both air brake systems. If pressure drops below 75 psi (± 5 psi) in either system, the warning buzzer and warning light will go on. Determine the cause of failure before proceeding. Primary air pressure is supplied to the rear brakes and is indicated by the green pointer on the gauge. Secondary air pressure is supplied to the steering axle brakes and indicated by the orange pointer.
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