Yale GDP100 Warning Light Symbols and What They Mean

The Yale GDP100 is a heavy-duty diesel forklift designed for demanding industrial applications, featuring robust systems to ensure operator safety and machine longevity. Its instrument cluster provides key operational feedback and alerts to maximize uptime and prevent costly damage. Understanding these indicator lights is essential for safe and efficient forklift operation.

How to read the colors: Red lights indicate immediate hazards or failures that require the forklift to be stopped right away. Amber lights warn of issues that need prompt attention but may not require an immediate stop, while green and blue lights typically show normal system status or active features.

Yale GDP100 Warning Light Symbols

SymbolNameColorWhat it meansWhat to do
Master Warning (Stop)REDSignals a critical malfunction or unsafe condition detected by the GDP100’s systems, often accompanied by an audible alarm.Safely stop the forklift and check the display for detailed information.
Master CautionAMBERIndicates a non-critical system fault or warning that should be addressed soon to avoid further issues.Review the operator display for specific cautions and plan corrective action.
Check Engine (MIL)AMBERThe engine management system has detected a fault affecting performance or emissions in the GDP100.Schedule service and avoid heavy loads until the problem is diagnosed.
Engine Oil PressureREDEngine oil pressure has dropped below safe operating levels, risking severe engine damage.Shut down the engine immediately and inspect oil level and leaks.
Battery / ChargingREDThe alternator is not charging the battery, or battery voltage is critically low on the GDP100.Turn off non-essential electrical loads and have the charging system checked.
Coolant TemperatureREDEngine coolant temperature has exceeded the safe limit, which can quickly lead to engine overheating.Stop the forklift, allow the engine to cool, and check coolant level.
ATTransmission TempREDTransmission fluid temperature is dangerously high, threatening gearbox integrity.Cease operation and let the transmission cool before continuing.
Brake SystemREDA major brake fault is present, such as low fluid or hydraulic failure, compromising stopping ability.Do not operate the forklift until brakes are inspected and repaired.
PParking BrakeREDThe parking brake is engaged, or there is a malfunction in the parking brake circuit.Release the parking brake before driving or check for system faults.
Seat BeltAMBERThe operator seat belt is not fastened, or the seat switch detects absence.Ensure the seat belt is securely fastened before use.
DPF / RegenerationAMBERThe Diesel Particulate Filter is full and the GDP100 requires a regeneration cycle.Initiate or complete the regeneration process as instructed in the operator manual.
DEF / AdBlueAMBERThe DEF (AdBlue) level is low, which will soon limit engine power or prevent starting.Refill the DEF tank with the correct fluid promptly.
Water in FuelAMBERWater has accumulated in the fuel separator, risking injector or pump damage.Drain the water separator before further operation.
Low FuelAMBERDiesel fuel level is nearing empty, risking engine shutdown.Refuel the GDP100 at the next opportunity.
Hydraulic SystemAMBERA hydraulic system fault or low fluid condition has been detected.Check hydraulic fluid level and inspect for leaks.
Reduced Power (Limp Mode)AMBERThe GDP100's engine control has limited power output due to a detected fault.Reduce load and seek service to restore full performance.
Hydraulic OilAMBERHydraulic oil temperature is elevated or oil level is low.Allow the system to cool and check fluid levels.
Engine Oil TemperatureREDEngine oil temperature is excessively high, risking engine lubrication failure.Stop the engine and allow it to cool before investigating.
Air FilterAMBERThe air filter is clogged, restricting airflow to the engine and reducing performance.Inspect and clean or replace the air filter.
Fuel Filter / Water SeparatorAMBERThe fuel filter is clogged or water separator needs draining, risking fuel starvation.Replace the filter or drain water as needed.
Service / Hour MeterAMBERScheduled maintenance interval has been reached based on engine hours.Schedule and perform required service tasks.
Work LightsBLUEIndicates the GDP100’s work lights are switched on for improved visibility.No action needed unless lights are not functioning.
Beacon / Rotating LightAMBERThe safety beacon is active to alert nearby personnel of forklift movement.No action required unless beacon is not operating.
Overload / CapacityREDThe load being lifted exceeds the rated capacity of the GDP100, risking tip-over.Lower the load immediately and verify weight before retrying.
Brake Fluid LevelREDThe brake fluid reservoir is low, which can compromise braking performance.Top up brake fluid and inspect for leaks.

25 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.

Most Important Warning Lights

Engine Oil Pressure Warning

Common causes

  • Low engine oil level
  • Oil pump failure
  • Blocked oil filter

What to do

Immediately stop the GDP100, check and top up engine oil if needed, and inspect for leaks or mechanical faults before restarting.

Coolant Temperature Warning

Common causes

  • Low coolant level
  • Radiator blockage
  • Failed thermostat or water pump

What to do

Shut down the engine, allow it to cool, check coolant level, and inspect the radiator and hoses for blockages or leaks.

Transmission Overtemperature

Common causes

  • Low transmission fluid
  • Heavy or prolonged load
  • Cooling system fault

What to do

Let the transmission cool down, check fluid level, and reduce load; consult service if the warning persists.

Brake System Fault

Common causes

  • Hydraulic leak
  • Worn brake pads
  • Brake fluid loss

What to do

Do not operate the forklift further; inspect the brake system for leaks, worn components, and fluid level before use.

Overload / Capacity Exceeded

Common causes

  • Attempting to lift excessive weight
  • Incorrect load distribution
  • Malfunctioning load sensor

What to do

Lower the load immediately, verify weight against the GDP100’s data plate, and ensure the load is balanced before proceeding.

Frequently Asked Questions

What should I do if the DPF regeneration light stays on in my GDP100?

Follow the on-display prompts to complete a parked regeneration cycle; if the light remains, contact service to avoid engine derating.

Why does my GDP100 show a DEF/AdBlue warning even after refilling?

The system may require a short drive or ignition cycle to reset; if the warning persists, there may be a sensor or quality issue.

Is it safe to keep operating with the hydraulic warning light on?

No, operating with a hydraulic fault can lead to loss of lifting or steering, so check fluid levels and inspect for leaks immediately.

What causes the air filter warning to appear on my GDP100?

A clogged air filter from dust or debris triggers the warning; inspect and clean or replace the filter as needed for optimal performance.

How often should I service the GDP100 when the hour meter light comes on?

Service intervals are based on engine hours; refer to the Yale GDP100 maintenance schedule and complete all recommended checks when prompted.