Instruments

The ABS indicator illuminates when there is a malfunction in the vehicle antilock brake system (ABS).

The check engine warning indicator illuminates when certain faults are detected. If a critical engine condition exists (for example, low oil pressure or high coolant temperature), the check engine indicator will illuminate to alert the driver to correct the condition as soon as possible. If the condition gets worse, the stop engine indicator will illuminate.

The check transmission indicator notifies the driver of three things. Any of the following items could be the cause for activating the lamp:

When the check transmission indicator illuminates, refer to the Allison Operator's Manual or contact customer support at Allison Transmission to determine the specific cause activating the indicator.

The cruise control indicator illuminates when the cruise control is activated.

The DEF quality indicator activates when the DEF concentration is diluted or contaminated.

Solid illumination indicates a regeneration is required. Change to a more challenging duty cycle, such as highway driving, to raise exhaust temperatures for at least 20 minutes, or perform a stationary regeneration. See the engine operation manual for details.

Blinking indicates that a stationary regeneration is required immediately. An engine derate and shutdown will occur. See the instructions in the engine manufacturer's operator's manual to perform a stationary regeneration.

The emergency buzzer sounds during the ignition sequence and whenever one of the following conditions exists:

Illuminates when the engine brake is enabled.

The fasten seat belt warning indicator (seat belt icon) illuminates for 3 seconds after the ignition switch is turned on.

When the engine is operating, if the driver's seat belt is unfastened and the park brake is not set, the seat belt warning indicator illuminates and a warning chime activates. The warning chime will remain active for 10 seconds. The warning indicator remains illuminated until the driver's seat belt is fastened.

The high-beam indicator (sideways beam icon) illuminates when the headlight high beams are on.

The high coolant temperature warning lamp (thermometer icon) and emergency buzzer activate whenever the coolant temperature goes above a preset maximum specified by the engine manufacturer.

For more information, see the engine manufacturer's manual provided with the vehicle.

A slow (10-second) flash, indicates a regeneration is in progress, and the driver is not controlling the engine idle speed.

A solid illumination indicates potentially hazardous exhaust temperatures at the outlet of the tail pipe if speed is below 5 mph (8 km/h). It does not signify the need for service; it only alerts the vehicle operator of high exhaust temperatures. See the engine operation manual for details.

The hydraulic brake system warning illuminates if there is a hydraulic brake system failure, or if the vehicle is powered and the engine is not running.

The left-turn indicator flashes on and off when the left-turn signal lights are flashing.

Both turn signal indicators flash when the hazard warning flasher is turned on.

The low air brake pressure warning indicator and emergency buzzer activate when the engine is turned on if air pressure in the primary or secondary air reservoir is below 65 to 75 psi (448 to 517 kPa), and remain on until air pressure rises above that level in both reservoirs.

The low battery voltage warning indicator (battery icon) illuminates when the battery voltage drops below 12 volts.

The low oil pressure warning lamp (oil can icon) and emergency buzzer activate whenever the engine oil pressure goes below the preset minimum specified by the engine manufacturer. See the engine manufacturer's manual for further information.

When the maintenance warning lamp illuminates, the message display center will alert the driver as follows:

Indicates an engine emissions-related fault, including, but not limited to the aftertreatment system. See the engine operation manual for details.

The parking brake on indicator activates when the parking brake is engaged.

If the vehicle is moving at a speed of 2 mph (3 km/h) or more, the emergency buzzer will sound until the parking brake is released.

The range inhibit (ICU3S panel) or shift inhibit (Ametek panel) indicator illuminates whenever all conditions for safe transmission shifting have not been met.

The right-turn indicator flashes on and off when the right-turn signal lights are flashing.

Both turn signal indicators flash when the hazard warning flasher is turned on.

The service transmission indicator activates when the transmission requires service. For example the transmission oil or filter may need to be changed. When the service transmission indicator illuminates, refer to the Allison Operator's Manual or contact customer support at Allison Transmission to determine the specific cause activating the indicator.

The stop engine warning indicator illuminates when the protection system available for the engine has been activated. On some engines, the engine electronic control unit (ECU) will derate the engine, allowing it to run, but at lower rpm and slower vehicle speed. The vehicle may be driven to a safe location.

The engine ECU will derate the engine. The driver must safely bring the vehicle to a stop on the side of the road.

To restart the engine turn the ignition switch to OFF, leave it there a few seconds, and turn the switch to START.

The tire pressure monitoring system indicator illuminates when the system detects an issue with one or more tires such as under or over pressure or over temperature. A warning message also appears in the driver display screen. See Fig. 6.3 .

The traction control indicator illuminates when the wheels lose traction.

The transmission overheat warning (ICU3S panel) illuminates when the temperature of the transmission fluid goes above the preset level set by the transmission manufacturer.

For more information, see the transmission manufacturer's manual provided with the vehicle.

The water in fuel indicator illuminates when the system detects water in the fuel tank.

Drain any water collected in the fuel/water separator.

The wheel spin indicator illuminates during a wheel spin event and the automatic traction control (ATC) system activates.

The optional indicator lamps that are available include: intake heater on indicator, low brake fluid warning, low coolant warning, low fuel warning, automatic transmission range inhibit warning, pall filter indicator, differential lock warning, and wheel spin indicator.

Three kinds of speedometer faces are available. The U.S. version of the speedometer registers speed in both miles per hour (mph) and kilometers per hour (km/h), with mph in larger numbers. See Fig. 6.7 .

The NAFTA version (not shown) of the speedometer face reverses this arrangement, with km/h in larger numbers. The metric-only version (not shown) shows km/h exclusively.

The tachometer indicates engine speed in revolutions per minute (rpm) and serves as a guide for shifting the transmission and keeping the engine in the appropriate rpm range. See Fig. 6.7 .

If the engine oil pressure falls below preset levels set by the engine manufacturer, the check engine lamp will illuminate, and, if the condition does not improve, the stop engine lamp will also illuminate and the buzzer will sound. At this point, the engine will derate or shut down, depending on the type of engine protection system installed. See Fig. 6.8 for an example of the engine oil pressure gauge.

During normal engine operation, the coolant temperature gauge should read 175 to 195°F (79 to 91°C). See Fig. 6.9 . If the temperature remains below 160°F (71°C) or exceeds 225°F (107°C), inspect the cooling system to determine the cause. See the vehicle workshop manual for troubleshooting and repair procedures.

The coolant temperature gauge is mission-critical. See Fig. 6.9 . If the coolant temperature rises above 225°F (107°C), first, the check engine lamp will illuminate, and, if the condition does not improve, the stop engine lamp will also illuminate and the buzzer will sound. At this point, the engine will derate or shut down, depending on the type of engine protection system installed.

For engines that are EPA10-compliant or newer, the fuel and DEF levels are measured in a dual purpose fuel/DEF gauge. See Fig. 6.10 .

The diesel fuel level is indicated at the top of the gauge, with a low-level warning lamp that illuminates when the diesel fuel level registers 1/8th of capacity. One fuel gauge is standard. If equipped with a second (optional) fuel gauge, each fuel tank level is indicated on a separate gauge.

The DEF level is indicated in the lower portion of the gauge. There is a low DEF level warning lamp that illuminates when the DEF level reaches 10% of capacity. See Chapter 8 for details of the DEF gauge functions.

Air pressure gauges register the pressure in the primary and secondary air systems. Normal pressure with the engine running is 100 to 120 psi (690 to 827 kPa) in both systems. See Fig. 6.11 .

Air pressure gauges are required on all vehicles with air brakes. A low-air-pressure warning lamp and buzzer, connected to both the primary and secondary systems, activate when air pressure in either system drops below a minimum pressure of 65 to 75 psi (448 to 517 kPa).

When the engine is started, the warning lamp and buzzer remain on until air pressure in both systems exceeds minimum pressure.

The voltmeter is a digital readout located on the bottom line of the driver display screen whenever the ignition switch is turned on.

It indicates the vehicle charging system voltage when the engine is running and the battery voltage when the engine is stopped. By monitoring the voltmeter, the driver can be aware of potential charging system problems and have them fixed before the batteries discharge enough to create starting difficulties.

The voltmeter will normally show approximately 13.7 to 14.1 volts when the engine is running. The voltage of a fully charged battery is 12.7 to 12.8 volts when the engine is stopped. Battery voltage under 12.0 volts is considered a low battery, and a completely discharged battery will produce only about 11.0 volts. The voltmeter will indicate lower voltage as the vehicle is being started or when electrical devices in the vehicle are being used.

If the voltmeter shows an undercharged or overcharged condition for an extended period, have the charging system and batteries checked at a repair facility.

The air intake restriction gauge indicates the vacuum on the engine side of the air cleaner. On standard installations, it is mounted on the air intake duct in the engine compartment. See Fig. 6.12 . As an option for easier viewing, the intake-air restriction indicator can be mounted on the dash, usually on the right-hand control panel.

Air intake restriction vacuum is measured in inches of water (inH₂O). For vehicles equipped with a graduated indicator or a restriction gauge on the dash, check the gauge with the engine off. If the yellow signal stays locked in the red zone once the engine is shut down, or is at or above 25 inH₂O, the air cleaner element needs to be replaced.

An optional ammeter measures current flowing to and from the battery. See Fig. 6.13 . When the batteries are being charged, the meter needle moves to the plus side of the gauge; when the batteries are being discharged, the needle moves to the minus side. A consistent negative reading when the engine is running indicates a possible problem with the charging system.

During normal operation, the optional rear axle oil temperature gauge should read between 160 and 220°F (71 and 104°C) for Detroit™ and Meritor™ drive axles. See Fig. 6.14 .

Under heavy loads, such as when climbing steep grades, temperatures up to a maximum of 250°F (121°C) are not unusual.

The optional digital clock has black characters on a constantly backlighted green display, with a brightness that automatically adjusts for day or night. The clock has a 24-hour alarm, with a three-minute snooze feature. See Fig. 6.15 .

During normal operation, the optional engine oil temperature gauge should read between 180 to 225°F (82 to 107°C) for Cummins ISB engines.

An optional pyrometer can be installed on the exhaust pipe. A pyrometer registers the exhaust temperature near the turbocharger. See Fig. 6.17 . Maximum exhaust temperature for the Cummins ISB engine is 1290°F (700°C).

Variations in engine load can cause exhaust temperatures to vary. If the pyrometer reading shows that exhaust temperature exceeds normal, reduce fuel to the engine until the exhaust temperature is reduced. Shift to a lower gear if the engine is overloaded.

During normal operation, the transmission fluid temperature gauge reading should not exceed 250°F (121°C). See Fig. 6.18 .

A turbocharger boost pressure gauge measures the pressure in the intake manifold, in excess of atmospheric pressure, being created by the turbocharger. See Fig. 6.19 .