Overview of Instruments
Before driving this vehicle, locate the instruments and controls, and become thoroughly familiar with their operation. After starting and when driving, ensure that the instrument readings are normal.
The instrument cluster provides system/component condition information to the driver. This information is available to assist the driver in determining any necessary actions. The instrument cluster consists of the following components: condition indicators (tell-tales), driver information display (DID), gauges, speedometer and tachometer, on board diagnostic (OBD) fault and warning indicators.
1. Condition Indicators (Tell-tale)
2. Driver Information Display (DID)
3. On Board Diagnostic (OBD) Fault and Warning Indicators
Coolant Temperature Gauge
The coolant temperature gauge indicates engine coolant temperature. The normal operating temperature for Mack engines is 80 to 105° C (170–215° F). If the temperature remains below or exceeds the normal temperature range, the cooling system should be checked for problems by an authorized Mack Vehicle dealer. When coolant temperature is excessive, the red STOP tell-tale illuminates and the buzzer will sound. The engine is at risk and the ECM may derate the engine power. Stop at the first safe place where the problem can be checked.
Engine Oil Pressure Gauge
Indicates engine oil pressure. When the engine oil pressure is too low, the red STOP tell-tale illuminates and the buzzer will sound. If the engine oil pressure becomes low, the engine is at risk. Bring the vehicle to a safe stop where the problem can be checked.
Secondary Brake Air Pressure Gauge
The secondary brake air pressure gauge is connected to the front circuit tank via sensors mounted on the passthrough wall. The front and rear air gauges should register equal air pressure. By observing the gauge pointers, the operator can detect a pressure drop if an air leak develops and can readily identify the circuit affected.
High Exhaust System Temperature (HEST) Indicator
The HEST Indicator illuminates 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 regeneration while the vehicle is moving, the HEST indicator will only illuminate 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.
A Power Take-Off (PTO) is a device that transfers power from the engine to another piece of equipment attached to the vehicle. Some examples include cement mixers and the compactor on a garbage vehicle.
A maximum of four PTOs can be operated in unison. One PTO is preset as a priority component. The remaining PTOs are preset as secondary, third or fourth in priority. The priority settings are dependent on the PTO preset arrangement and the number of PTOs available. There are three basic types of PTOs available: engine-mounted, transmission-mounted, and drive shaft-mounted. The engine-mounted PTO is direct-mounted to the engine and is engaged with a bypass valve operated by an internal switch.
The transmission-mounted PTO is clutch-dependent, which means that operation can be regulated by depressing or releasing the clutch pedal. For mDrive transmissions, this is controlled by the Transmission Electronic Control Unit (TECU). If the vehicle has an automatic transmission the PTO operation and speed adjustment is controlled via an interior switch. Depending on customer specification, some transmission-mounted PTOs are not operable when driving the vehicle. The drive shaft-mounted PTO consists of an additional gearbox that divides the drive shaft into two shafts. One shaft drives the vehicle’s axle. The other shaft drives the PTO.