The Mack GU713 is a versatile vocational truck designed for demanding applications like dump, mixer, and refuse. Its instrument cluster provides critical alerts to ensure safety and efficiency on job sites and highways.
Mack GU713 Warning Light Symbols
| Symbol | Name | Color | What it means | What to do |
|---|---|---|---|---|
| Master Warning (Stop) | RED | A serious fault in the GU713, such as low oil pressure or brake failure, demands immediate shutdown to prevent engine damage. | Safely pull over, stop the engine, and check the primary fault indicator. | |
| Master Caution | AMBER | A non-critical issue in the GU713 (e.g., low DEF or DPF regen needed) requires attention soon to avoid escalation. | Review other warning lights and address the related system at the next stop. | |
| Check Engine (MIL) | AMBER | The Mack MP engine control module has detected an emission or performance fault, common on GU713 with MP7/MP8 engines. | Schedule a diagnostic scan at a Mack dealer; if flashing, reduce load and drive to service. | |
| Engine Oil Pressure | RED | Low oil pressure in the GU713's MP engine can cause catastrophic failure if ignored. | Stop engine immediately and check oil level; do not restart until resolved. | |
| Battery / Charging | RED | The alternator is not charging the battery, leaving the GU713's electrical systems at risk of failure. | Check battery connections and alternator belts; seek service if light stays on. | |
| Coolant Temperature | RED | Engine coolant temperature is too high, risking overheating in the GU713's MP engine under heavy loads. | Reduce load, idle engine, and check coolant level; do not operate until cool. | |
| Transmission Temp | AMBER | Transmission fluid temperature is elevated, which can degrade the Allison or mDrive unit in the GU713. | Shift to a lower gear or stop and idle to cool transmission. | |
| Brake System | RED | The GU713's air brake system has low pressure or an imbalance, compromising stopping ability. | Park immediately, engage parking brake, and inspect air system for leaks. | |
| ABS | AMBER | The anti-lock brake system on the GU713 is malfunctioning, reducing traction control on slick surfaces. | Drive cautiously to a service center; braking remains functional but without ABS. | |
| Parking Brake | RED | The parking brake is engaged on the GU713, or the system has a fault preventing release. | Release parking brake before moving; if light stays on, check brake valve. | |
| Tire Pressure (TPMS) | AMBER | One or more tires on the GU713 have low pressure, which can cause blowouts under heavy loads. | Check tire pressures and inflate to spec; inspect for damage. | |
| Seat Belt | RED | The driver's seat belt is not fastened in the GU713, a violation that also disables some safety systems. | Fasten seat belt immediately. | |
| Glow Plug / Preheat | AMBER | The glow plugs are heating for cold start on the GU713's MP engine; light turns off when ready. | Wait for light to go out before cranking engine. | |
| DPF / Regeneration | AMBER | The diesel particulate filter in the GU713's exhaust needs regeneration to clear soot buildup. | Drive at highway speed to initiate passive regen or perform parked regen per manual. | |
| DEF / AdBlue | AMBER | Diesel exhaust fluid level is low in the GU713, which will eventually derate engine speed. | Add DEF at next fuel stop; do not let tank run empty. | |
| Water in Fuel | AMBER | Water has been detected in the fuel water separator of the GU713, risking injection damage. | Drain the water separator immediately. | |
| Low Fuel | AMBER | Fuel level in the GU713's tanks is low; plan refueling soon to avoid running out. | Refuel as soon as possible. | |
| High Beam | BLUE | High beam headlights are activated on the GU713, increasing forward visibility. | Dim when approaching oncoming traffic. | |
| Power Steering (EPS) | AMBER | The electric power steering system in the GU713 has a fault, making steering heavy at low speeds. | Proceed carefully to a service center; avoid low-speed maneuvers if possible. | |
| Hydraulic System | AMBER | Hydraulic system on GU713 (if equipped with dump or mixer) has low fluid or pressure. | Check hydraulic fluid level and inspect for leaks before operating equipment. | |
| Reduced Power (Limp Mode) | AMBER | The GU713's engine has entered limp mode to protect against damage, limiting speed and power. | Drive to nearest service facility at reduced speed; have fault codes read. | |
| Air Brake Pressure (Low) | RED | Air brake reservoir pressure is below safe operating level in the GU713, risking brake lockup. | Stop immediately and wait for compressor to build pressure; check for leaks. | |
| Engine / Exhaust Brake | AMBER | The engine brake or exhaust brake is engaged on the GU713, helping slow the truck. | Disengage if not needed to save fuel. | |
| Trailer | AMBER | The trailer ABS or connection on the GU713 has a fault, reducing trailer braking performance. | Check trailer electrical connector and ABS fuse. | |
| High Exhaust Temp (HEST) | AMBER | Exhaust temperature is elevated during DPF regeneration on the GU713; avoid parking over combustibles. | Ensure area is clear of flammable materials; regeneration will complete automatically. | |
| Fasten Seat Belt | RED | Seat belt reminder for driver or passenger in GU713; unbuckled belt triggers this alert. | Fasten seat belt before moving the truck. |
26 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.
Most Important Warning Lights
Engine Overheat
Common causes
- Low coolant level
- Failed water pump
- Clogged radiator or charge air cooler
What to do
On a GU713, safely pull over and let the MP engine idle with the hood open to cool. Check coolant reservoir and look for leaks; do not open hot cap. If water pump failed, tow to dealer.
Air Brake Failure
Common causes
- Compressor failure
- Leaking air line
- Faulty brake valve
What to do
Park the GU713 immediately and apply parking brake. Inspect air lines for audible leaks; if compressor is faulty, the truck must be towed. Do not drive without air pressure.
Low Oil Pressure
Common causes
- Low oil level
- Oil pump failure
- Blocked oil filter or pick-up
What to do
Stop the GU713's engine right away. Check dipstick; if low, add oil. If light persists, do not restart; tow to Mack service for pump or filter issue.
Transmission Overheat
Common causes
- Low fluid level
- Excessive load or torque converter slip
- Cooler blockage
What to do
In the GU713, shift to neutral and idle to cool the Allison or mDrive. Check fluid level (hot, running). If recurring, inspect transmission cooler for debris.
DEF System Malfunction
Common causes
- Empty DEF tank
- Faulty DEF injector
- Contaminated or crystallized fluid
What to do
If DEF warning appears on GU713, fill tank with certified fluid. If light stays on, a dealer must clear the fault and may need to clean or replace the injector.
Frequently Asked Questions
Why does my GU713's check engine light flash on and off?
A flashing check engine light on a Mack GU713 indicates a severe misfire or catalyst damage risk. Reduce load immediately and head to a dealer for diagnosis.
Can I drive the GU713 with the DPF regen light on?
Yes, but you should drive at highway speeds to promote passive regeneration. If the light stays on, perform a parked regen in a safe, well-ventilated area.
What does the master caution light mean on my GU713?
The master caution light alerts you to a non-critical issue, such as low DEF or a fault in a secondary system. Check other warning lights for specifics.
How often should the water separator be drained on a GU713?
Mack recommends draining the water separator at every oil change or when the water-in-fuel light illuminates. On the GU713, the separator is typically mounted on the frame rail.
Why is my GU713's transmission temperature light on after heavy hauling?
The GU713's transmission temp light may come on if you've been hauling at maximum GCWR in hot weather. Stop, idle in neutral, and check fluid level. Use a lower gear to reduce heat.
Is it safe to drive with the ABS light on in a GU713?
You still have normal braking, but ABS is disabled. Drive cautiously, especially on slippery roads, and have the system inspected soon at a Mack shop.