The Mack Granite instrument cluster is engineered for demanding construction and heavy-duty hauling applications. It relays vital alerts from the MP-series engine and the Mack-specific chassis systems, helping operators avoid downtime on the job site.
Mack Granite Warning Light Symbols
| Symbol | Name | Color | What it means | What to do |
|---|---|---|---|---|
| Master Warning (Stop) | RED | This red stop sign indicates a critical fault that demands the engine be shut down immediately to prevent damage. | Stop the truck safely, shut off the engine, and contact Mack service. | |
| Master Caution | AMBER | An amber triangle alerts you to a non-critical system issue that still requires attention soon. | Check the message center and address the fault at the next scheduled stop. | |
| Check Engine (MIL) | AMBER | Illuminates when the MACK engine's emissions-control system detects a malfunction that could affect performance or compliance. | Have the fault code read by a Mack dealer; avoid operating if flashing. | |
| Engine Oil Pressure | RED | Indicates dangerously low oil pressure in the MP-series engine, risking severe engine wear or seizure. | Shut down the engine immediately and check oil level and for leaks. | |
| Battery / Charging | RED | The Mack Granite’s charging system is not maintaining proper voltage, possibly due to alternator or battery failure. | Reduce electrical loads and head to a service bay; if red, shut down. | |
| Coolant Temperature | RED | Engine coolant temperature has exceeded the safe limit for the Mack MP7/MP8, risking overheating damage. | Pull over, idle engine to cool, and check coolant level and fan operation. | |
| Transmission Temp | AMBER | The Mack mDRIVE or Allison transmission fluid is running hotter than normal, reducing lubricity. | Downshift or reduce load; if light stays on, service transmission. | |
| Brake System | RED | A critical fault in the air brake system, such as low air pressure or a leak, compromising stopping ability. | Stop immediately and do not drive until brake air pressure is restored and system is checked. | |
| ABS | AMBER | The anti-lock braking system on your Mack Granite has a fault; normal braking remains but ABS is disabled. | Drive to a Mack service center to diagnose wheel-speed sensors or modulator valves. | |
| Parking Brake | RED | Indicates the parking brake is engaged; if flashing, a system fault may exist in the spring brake chambers. | Release the parking brake; if light stays on, have the brake valve inspected. | |
| Tire Pressure (TPMS) | AMBER | At least one tire on the Granite is significantly underinflated, affecting fuel economy and tire life. | Check tire pressures at the next stop and inflate to recommended psi. | |
| Airbag (SRS) | AMBER | The supplemental restraint system has a fault; airbags may not deploy in an accident. | Schedule a Mack dealer inspection to diagnose the SRS module or wiring. | |
| Seat Belt | RED | The driver’s seat belt is not fastened while the ignition is on, or the buckle sensor is faulty. | Fasten your seat belt; if light persists, check the buckle connection. | |
| Glow Plug / Preheat | AMBER | The intake heater or glow plugs are active to aid cold starts; light turns off when preheat is complete. | Wait for the light to go out before cranking the engine. | |
| DPF / Regeneration | AMBER | The diesel particulate filter is actively regenerating to burn off soot; exhaust temperature will be high. | Continue driving; if light flashes, park and initiate stationary regen via the dash button. | |
| DEF / AdBlue | AMBER | Diesel exhaust fluid level is low; the Mack Granite’s SCR system will eventually limit engine power. | Add DEF at the next opportunity; use only DEF meeting ISO 22241. | |
| Water in Fuel | AMBER | Water has accumulated in the fuel/water separator, which can cause injector damage on the MP engine. | Drain the water separator immediately; if light stays on, replace the filter. | |
| Low Fuel | AMBER | Fuel level is below 1/8 tank; the Mack Granite’s range is limited and running out can air-lock the fuel system. | Refuel as soon as possible, especially when hauling heavy loads. | |
| High Beam | BLUE | The high-beam headlights are turned on, providing maximum forward lighting. | Dim to low beams when approaching oncoming traffic to avoid glare. | |
| Power Steering (EPS) | RED | Electric power steering assist is lost; steering will be heavy and difficult, especially at low speeds. | Reduce speed and steer carefully; have the EPS module checked at a Mack dealer. | |
| Reduced Power (Limp Mode) | AMBER | The engine control system has limited power to prevent damage or emissions violations. | Drive to a safe location and contact Mack service; heavy loads may require towing. | |
| Air Brake Pressure (Low) | RED | Air brake system pressure has dropped below 60 psi, making brakes unreliable. | Stop immediately and build air pressure; do not move until pressure is normal. | |
| Engine / Exhaust Brake | GREEN | The Mack engine brake or exhaust brake is activated, providing auxiliary braking. | Use on downgrades to save service brakes; disable on slippery surfaces. | |
| Trailer | AMBER | A fault exists in the trailer’s electrical or braking system, such as a broken ABS wire. | Check trailer connections and lights; service trailer at next stop. | |
| High Exhaust Temp (HEST) | AMBER | Exhaust temperature is elevated, often during regen; the truck will tell you when it’s safe to park. | Avoid parking over flammable materials until the light goes out. |
25 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.
Most Important Warning Lights
Engine Overheating
Common causes
- Low coolant level
- Failed fan clutch
- Thermostat stuck closed
What to do
On your Mack Granite, immediately reduce engine load and idle to cool. Check the coolant reservoir; if low, add approved coolant only after the engine cools. If the fan does not engage, the fan clutch may need replacement.
Low Oil Pressure
Common causes
- Insufficient oil level
- Oil pump failure
- Worn engine bearings
What to do
Shut off the MP-series engine the moment this light appears. Verify oil level on the dipstick; if low, add 15W-40. If level is fine, do not restart—tow to a Mack service center to avoid catastrophic failure.
DEF System Fault
Common causes
- Low DEF quality
- DEF pump failure
- NOx sensor malfunction
What to do
The SCR system on the Mack Granite will derate power if untreated. Top off with fresh DEF; if the light persists, a dealer must diagnose the pump or sensors to avoid 5 mph speed limitation.
Brake System Air Leak
Common causes
- Damaged air line
- Faulty brake valve
- Loose fitting
What to do
If the brake system warning is red, stop safely and build air pressure. Listen for hissing near the treadle valve or gladhands on the Granite. Tighten fittings or replace damaged hoses before continuing.
DPF Regeneration Required
Common causes
- Soot buildup from excessive idling
- Faulty exhaust temperature sensor
- Malfunctioning regen valve
What to do
The Mack Granite’s DPF needs active regen; drive at highway speeds for 20 minutes. If the light flashes, park in a safe area and press the regen button on the dash—ensure no flammable materials underneath.
Frequently Asked Questions
What does the Check Engine light mean on a Mack Granite?
It signals an emissions-related fault in the Mack MP engine. It could be a loose fuel cap, a failing EGR valve, or a DPF issue. Have the codes read by a Mack dealer promptly to avoid derates.
How do I start a manual DPF regeneration on my Mack Granite?
Park the truck away from flammables, engage the parking brake, and press and hold the regen switch on the dash for 2 seconds. The engine will idle higher for about 20 minutes; ensure exhaust stays clear.
What do I do if the DEF low light comes on?
The Granite will count down miles until power is limited. Add DEF immediately—the fill cap is located behind the cab on the driver’s side. Use only DEF that meets ISO 22241 standards.
Why is my ABS light on while driving?
A wheel-speed sensor may be dirty or damaged, common on construction sites. Normal braking works, but without ABS. Clean sensor tips or schedule a visit to a Mack dealer for diagnosis.
What does the transmission temperature warning mean?
The Mack mDRIVE or Allison transmission is overheating. Reduce load, downshift, or stop and idle in neutral to cool the fluid. Check for low fluid level if the light stays on.
Why is the battery light flickering?
A loose alternator belt or failing voltage regulator on the Granite’s charging system. Check belt tension and inspect battery terminals for corrosion. If light stays on, the alternator may need replacement.