The JLG G6-42A telehandler's instrument cluster uses a combination of warning lights and gauges to keep you informed. Understanding these indicators is crucial for safe operation and preventing damage to the machine's Deutz diesel engine and hydraulic systems.
JLG G6-42A Warning Light Symbols
| Symbol | Name | Color | What it means | What to do |
|---|---|---|---|---|
| Master Warning (Stop) | RED | This light illuminates in red to indicate a critical fault that requires immediate engine shutdown on the G6-42A. | Stop the engine safely and consult the fault code display. | |
| Master Caution | AMBER | An amber caution alerts you to a non-critical system issue that needs attention on this telehandler. | Check the instrument panel for additional warning indicators and address the underlying condition. | |
| Check Engine (MIL) | AMBER | This light signals a malfunction in the G6-42A's Deutz engine management system, often related to emissions or fuel delivery. | Have the engine diagnostics scanned by a JLG dealer as soon as possible. | |
| Engine Oil Pressure | RED | Low engine oil pressure is indicated by this red lamp; continued operation can cause severe engine damage on the G6-42A. | Stop the engine immediately and check oil level and pressure sender. | |
| Battery / Charging | RED | This red light shows that the alternator is not charging the battery, which can lead to electrical failure on your telehandler. | Inspect alternator belt, connections, and battery condition. | |
| Coolant Temperature | RED | A red coolant temperature warning indicates the engine is overheating, risking severe engine damage on the G6-42A. | Stop the engine, let it cool, and check coolant level and radiator for blockages. | |
| Transmission Temp | RED | This light warns of excessive transmission oil temperature, which can degrade performance on the G6-42A's drivetrain. | Reduce load and allow transmission to cool; check fluid level. | |
| Brake System | RED | A red brake system warning indicates a potential fault in the service brakes or hydraulic brake circuit on the G6-42A. | Stop operation and inspect brake fluid level and lines for leaks. | |
| Parking Brake | AMBER | This amber light reminds you that the parking brake is engaged on your JLG telehandler. | Release the parking brake before moving the machine. | |
| Seat Belt | RED | This red indicator warns that the operator's seat belt is not fastened on the G6-42A, a critical safety requirement. | Fasten your seat belt immediately before operating. | |
| Glow Plug / Preheat | AMBER | This amber light illuminates during engine preheat on cold starts; wait for it to turn off before cranking on the G6-42A. | Wait for the light to extinguish, then start the engine. | |
| DPF / Regeneration | AMBER | This amber indicator shows that the diesel particulate filter is actively regenerating or requires a parked regeneration on the G6-42A. | If flashing, perform a stationary regeneration as per the operator’s manual. | |
| DEF / AdBlue | AMBER | This amber light warns of low Diesel Exhaust Fluid level or a system fault on the G6-42A's SCR emissions system. | Refill DEF tank or have the system serviced if the light stays on. | |
| Water in Fuel | AMBER | This amber light indicates that water has accumulated in the fuel filter/water separator on your telehandler. | Drain the water separator or replace the fuel filter element. | |
| Low Fuel | AMBER | This amber light reminds you that the fuel level is low and refueling is needed for the G6-42A's operation. | Refuel the machine as soon as possible. | |
| High Beam | BLUE | This blue light indicates that the high-beam headlights are on, improving visibility on the G6-42A. | Dim the high beams when approaching other vehicles or personnel. | |
| Hydraulic System | RED | This red warning signals a hydraulic system fault, such as low pressure or high temperature, on the G6-42A. | Stop the machine and check hydraulic oil level and for leaks. | |
| Reduced Power (Limp Mode) | AMBER | This amber light indicates the engine control system has reduced power to protect the G6-42A's drivetrain. | Operate at reduced speed and have the cause diagnosed promptly. | |
| Hydraulic Oil | AMBER | This amber light warns of low hydraulic oil level or high temperature in the G6-42A's hydraulic system. | Check hydraulic oil level and temperature; allow cooling if overheated. | |
| Air Filter | AMBER | This amber light indicates a clogged engine air filter, restricting airflow to the G6-42A's engine. | Inspect and replace the air filter element. | |
| Fuel Filter / Water Separator | AMBER | This amber light alerts you to water in the fuel or a clogged fuel filter on the G6-42A. | Drain the water separator and replace the fuel filter if needed. | |
| Service / Hour Meter | AMBER | This amber indicator reminds you that scheduled maintenance is due based on engine hours on the G6-42A. | Perform the required service as outlined in the maintenance schedule. | |
| Work Lights | GREEN | This green light shows that the work lights are turned on for improved visibility on the G6-42A. | Turn off work lights when not needed to conserve battery. | |
| Beacon / Rotating Light | GREEN | This green indicator confirms that the beacon light is active to warn others of the G6-42A's operation. | Ensure the beacon is on when operating in low-visibility areas. | |
| Swing / Slew Lock | AMBER | This amber light indicates that the swing lock is engaged, preventing the upper structure from rotating on the G6-42A. | Release the swing lock before attempting to swing the boom. | |
| Differential Lock | GREEN | This green light shows that the differential lock is engaged for maximum traction on the G6-42A. | Disengage the diff lock on hard surfaces to prevent driveline damage. | |
| Overload / Capacity | RED | This red light and alarm warn that the G6-42A is overloaded beyond its rated capacity, risking instability. | Immediately reduce load or retract boom to a safe position. | |
| Mast / Lift Limit | AMBER | This amber light indicates that the mast or boom has reached its maximum height or angle limit on the G6-42A. | Do not attempt to override; reduce height or angle slightly. | |
| Low Oil Level | AMBER | This amber light warns of low engine oil level in the G6-42A's crankcase. | Check and top up engine oil to the correct level. | |
| Brake Fluid Level | RED | This red light indicates low brake fluid level in the G6-42A's hydraulic brake system. | Check brake fluid reservoir and inspect for leaks. |
30 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
- Radiator blockage
- Failed cooling fan
What to do
Stop the G6-42A immediately, allow the engine to cool, then check coolant level and clean the radiator fins. If the fan is not operating, contact your JLG dealer.
Loss of Hydraulic Power
Common causes
- Low hydraulic oil
- Pump failure
- Hydraulic hose burst
What to do
Stop operation and check hydraulic oil level; inspect for visible leaks. If the level is low, top up with recommended oil. If the problem persists, have the system serviced by a JLG technician.
Engine Will Not Start (Cold Weather)
Common causes
- Glow plug malfunction
- Low battery voltage
- Fuel gelling
What to do
Ensure the glow plug light goes off before cranking. Use a battery booster if voltage is low. In extreme cold, use winter-grade fuel and consider adding anti-gel additive.
Machine Overloaded
Common causes
- Exceeding rated capacity
- Improper load distribution
- Boom extended too far
What to do
Immediately reduce load or reposition the telehandler. Refer to the load chart on the G6-42A and ensure the load is within limits for the current boom angle and extension.
DPF Regeneration Required
Common causes
- Ash buildup
- Frequent short trips
- Engine operating at low load
What to do
Perform a parked regeneration as described in the operator’s manual. If the warning continues, contact a JLG dealer to service the DPF system.
Frequently Asked Questions
What does the master warning light mean on my JLG G6-42A?
The red master warning light indicates a critical fault that requires immediate engine shutdown. Check the instrument panel for the specific warning symbol that will also be lit, such as oil pressure or engine temperature.
My check engine light is on. Can I still operate the telehandler?
You may continue operation if performance is unaffected, but you should have the engine diagnostics checked as soon as possible. The light could indicate an emissions or fuel system issue that might lead to reduced power or damage.
How do I perform a DPF regeneration on the G6-42A?
When the DPF regeneration light is flashing, park the machine on a hard surface away from combustibles, engage the parking brake, and depress the regeneration button (if equipped) or follow the prompts on the display. The engine will run at high idle until the process completes.
What should I do if the overload light comes on?
Stop any lift or extend functions immediately. Slowly retract the boom and lower the load. The overload warning on the G6-42A means the machine is unstable; continuing could cause tipping.
The seat belt light stays on even when I fasten the belt. What's wrong?
Check that the seat belt latch is fully engaged. If the light persists, there may be a faulty sensor in the buckle or wiring issue. Contact a JLG dealer for repair, as this light is critical for safety.
Why does my G6-42A show a master caution light with no other indicators?
The master caution is a general warning. It may be accompanied by a fault code on the display. Check the diagnostic menu or refer to the operator's manual to identify the underlying issue, such as a service interval reminder or a minor system fault.