The JLG 1850SJ is a heavy-duty telescopic boom lift designed for demanding aerial work. Its instrument cluster provides critical machine status and warnings to ensure safe operation. Understanding these indicators is essential for operators to prevent damage and accidents.
JLG 1850SJ Warning Light Symbols
| Symbol | Name | Color | What it means | What to do |
|---|---|---|---|---|
| Master Warning (Stop) | RED | A critical fault has occurred in the JLG 1850SJ's engine, hydraulics, or safety systems requiring immediate stop. | Stop the machine safely, engage parking brake, and check the display for the specific fault code. | |
| Master Caution | AMBER | A non-critical issue exists on the JLG 1850SJ that needs attention but does not require immediate shutdown. | Check the display for the condition and address at the next service opportunity. | |
| Check Engine (MIL) | AMBER | The JLG 1850SJ's engine control unit has detected a fault in the engine or emissions system. | Check the engine compartment for obvious issues and contact service to read fault codes. | |
| Engine Oil Pressure | RED | Engine oil pressure is below safe operating range on the JLG 1850SJ, risking severe engine damage. | Immediately shut down the engine and check oil level and for leaks before restarting. | |
| Battery / Charging | RED | The JLG 1850SJ's charging system is not supplying proper voltage to the battery. | Check alternator belt and battery connections; if light persists, service charging system. | |
| Coolant Temperature | RED | Engine coolant temperature has exceeded the safe limit on the JLG 1850SJ. | Stop engine and allow to cool; check coolant level and for leaks or blocked radiator. | |
| Brake System | RED | A fault has been detected in the JLG 1850SJ's braking system, reducing braking performance. | Stop the machine and do not operate until the brake system has been inspected and repaired. | |
| Parking Brake | RED | The parking brake on the JLG 1850SJ is engaged or has a malfunction indicating it may not hold. | Ensure parking brake is fully released; if light stays on, service parking brake system. | |
| Seat Belt | RED | The operator's seat belt on the JLG 1850SJ is not fastened or the buckle sensor is activated. | Fasten seat belt securely before moving the machine. | |
| Glow Plug / Preheat | AMBER | The glow plugs are active on the JLG 1850SJ's diesel engine for cold start preheating. | Wait for the light to turn off before attempting to start the engine. | |
| Low Fuel | AMBER | Fuel level in the JLG 1850SJ's tank is low and needs refueling soon. | Refuel the machine with the appropriate diesel grade to avoid running out. | |
| High Beam | BLUE | The high beam headlights are activated on the JLG 1850SJ. | Dim headlights when approaching other vehicles or personnel. | |
| Hydraulic System | RED | A critical hydraulic system fault is detected on the JLG 1850SJ, such as low pressure or contamination. | Stop all operations and inspect hydraulic fluid level and for leaks; call for service. | |
| Fasten Seat Belt | RED | The operator seat belt is not buckled on the JLG 1850SJ; machine may be immobilized. | Fasten the seat belt to resume operation. | |
| Reduced Power (Limp Mode) | AMBER | The JLG 1850SJ has entered reduced power mode to protect the engine or transmission due to a fault. | Reduce load and travel at low speed; contact service to diagnose the cause. | |
| Hydraulic Oil | AMBER | Hydraulic oil level is low or temperature is high on the JLG 1850SJ. | Check hydraulic oil reservoir and top up if needed; allow system to cool if hot. | |
| Engine Oil Temperature | RED | Engine oil temperature is too high on the JLG 1850SJ, risking lubrication failure. | Reduce engine load and idle to cool; check oil level and cooling system. | |
| Air Filter | AMBER | The engine air filter on the JLG 1850SJ is restricted and needs cleaning or replacement. | Clean or replace the air filter element as per maintenance schedule. | |
| Service / Hour Meter | AMBER | The JLG 1850SJ is due for scheduled maintenance based on engine hours. | Perform the required service as indicated in the operator's manual. | |
| Work Lights | GREEN | The work lights are turned on on the JLG 1850SJ. | Turn off when not needed to conserve battery power. | |
| Beacon / Rotating Light | GREEN | The rotating beacon is active on the JLG 1850SJ, indicating the machine is in operation. | Ensure beacon is on when operating in low-light or high-traffic areas. | |
| Swing / Slew Lock | AMBER | The turntable swing lock is engaged on the JLG 1850SJ, preventing rotation. | Release the swing lock before attempting to rotate the upper structure. | |
| Differential Lock | AMBER | The differential lock is engaged on the JLG 1850SJ for improved traction. | Disengage diff lock when operating on firm surfaces to avoid driveline damage. | |
| PTO Engaged | AMBER | The power take-off is engaged on the JLG 1850SJ, powering auxiliary equipment. | Disengage PTO when not in use to reduce load on the engine. | |
| Overload / Capacity | RED | The JLG 1850SJ's load capacity has been exceeded or the load moment indicator is active. | Remove load immediately and reposition to bring within safe limits. | |
| Low Oil Level | AMBER | Engine oil level is low on the JLG 1850SJ. | Check and add oil to the correct level as specified. | |
| Brake Fluid Level | RED | Brake fluid level is critically low on the JLG 1850SJ, affecting brake function. | Do not operate; top up brake fluid and inspect for leaks. | |
| Door Open | RED | The cab door or enclosure door is open on the JLG 1850SJ. | Close and latch the door securely before operating the machine. |
28 symbols shown. Icons follow ISO 2575 dashboard standards; exact graphics vary by model year.
Most Important Warning Lights
Low Engine Oil Pressure
Common causes
- Low oil level
- Oil pump failure
- Clogged oil filter
What to do
Immediately shut down the JLG 1850SJ. Check oil level with dipstick; if full, have oil pump and filter inspected by a technician before restarting.
Hydraulic System Overheat
Common causes
- Low hydraulic fluid
- Blocked cooler
- Continuous heavy use
What to do
Stop all boom functions and let the system cool. Check hydraulic oil level and clean the cooler fins. Avoid sustained high-demand operations.
Overload Condition
Common causes
- Exceeding rated capacity
- Unbalanced load
- Sensor malfunction
What to do
Immediately lower and remove the overload. Check the load chart and reposition. If light persists with no overload, call service to calibrate the load moment system.
Engine Coolant Overheat
Common causes
- Low coolant level
- Radiator blockage
- Faulty thermostat
What to do
Stop engine and let it cool. Check coolant reservoir and add if needed. Clean radiator debris and inspect for leaks. Do not operate until temperature is normal.
Brake System Failure
Common causes
- Brake fluid leak
- Worn brake pads
- Air in hydraulic lines
What to do
Stop the JLG 1850SJ immediately and do not move it. Check brake fluid level and inspect for leaks. Have the brake system bled and serviced before further use.
Frequently Asked Questions
What should I do if the Master Warning light comes on while operating the JLG 1850SJ?
Stop all operations immediately, lower the boom to a safe position, and engage the parking brake. Check the display for a fault code and refer to the operator's manual or call service.
Can I continue operating with the Master Caution light on?
Yes, but you should investigate the cause as soon as possible. The JLG 1850SJ will allow limited operation, but ignoring it may lead to a more serious issue. Check the display for the specific warning.
Why does the JLG 1850SJ have both a red and amber hydraulic system light?
The red light indicates a critical hydraulic fault (e.g., pressure loss) requiring immediate shutdown. The amber light indicates a less urgent issue like low oil level or high temperature, which should be addressed at the next opportunity.
How do I reset the service hour meter light on the JLG 1850SJ?
The service light resets automatically after a certain number of hours or can be reset by a technician using the diagnostic tool after performing the scheduled maintenance. Refer to the maintenance manual for details.
Is it normal for the glow plug light to stay on for a few seconds in cold weather?
Yes, the glow plug preheat cycle on the JLG 1850SJ's diesel engine can last several seconds in cold temperatures. Wait for the light to turn off before starting to ensure proper ignition.
What does the swing lock light indicate and can I drive with it on?
The swing lock light indicates that the turntable rotation is locked. You can drive the machine, but you will not be able to rotate the boom. Release the lock before attempting to swing.