The Manitou MLT 840 telehandler's instrument cluster provides critical real-time feedback for safe operation. Warning lights are color-coded to indicate urgency, with red demanding immediate stop, amber requiring attention, and green/blue indicating active systems or information.
Manitou MLT 840 Warning Light Symbols
| Symbol | Name | Color | What it means | What to do |
|---|---|---|---|---|
| Master Warning (Stop) | RED | Indicates a critical system failure requiring immediate engine shutdown on the Manitou MLT 840. | Stop the telehandler safely and consult the manual. | |
| Engine Oil Pressure | RED | Engine oil pressure has dropped below safe operating level for the MLT 840's Perkins engine. | Shut off engine immediately and check oil level and system. | |
| Battery / Charging | RED | Alternator is not charging the battery, or voltage is out of range for the MLT 840 electrical system. | Check battery connections and alternator belt; if persistent, service electrical system. | |
| Coolant Temperature | RED | Engine coolant temperature has exceeded safe limit for the MLT 840's diesel engine. | Stop engine and allow to cool; check coolant level and radiator for blockages. | |
| Brake System | RED | Brake system fault detected, potentially low brake fluid or worn pads on the telehandler. | Stop immediately and inspect brake fluid level and system integrity. | |
| Parking Brake | AMBER | Parking brake is engaged or a malfunction is detected in the MLT 840's brake mechanism. | If driving, disengage parking brake; if light stays on, service brake system. | |
| Glow Plug / Preheat | AMBER | Glow plugs are active during cold start of the MLT 840; light off indicates preheating complete. | Wait for light to turn off before cranking the engine. | |
| Water in Fuel | AMBER | Water has been detected in the fuel/water separator on the Manitou MLT 840 diesel system. | Drain water from the separator bowl; if persistent, service fuel system. | |
| Hydraulic Oil | AMBER | Hydraulic oil level is low or filter is clogged, affecting boom and attachment operation on the MLT 840. | Check hydraulic oil level and filter; top off or replace as needed. | |
| Air Filter | AMBER | Engine air filter restriction detected, reducing performance of the MLT 840's engine. | Check and clean or replace the air filter element. | |
| Service / Hour Meter | AMBER | Scheduled maintenance interval approaching or due for the MLT 840; light may flash based on hours. | Perform required service as per Manitou maintenance schedule. | |
| Work Lights | GREEN | Work lights on the MLT 840 mast or chassis are currently illuminated. | No action needed; indicates lights are active. | |
| Beacon / Rotating Light | GREEN | The amber rotating beacon is activated, indicating the MLT 840 is in operation or moving. | No action needed; ensures visibility for safety. | |
| Overload / Capacity | RED | Load on the telehandler exceeds rated capacity; stability is compromised on the MLT 840. | Immediately lower load and reduce outreach; never operate while overloaded. | |
| Seat Belt | RED | Operator seat belt is not fastened; telehandler will not operate until buckled on the MLT 840. | Fasten seat belt before starting or moving the machine. | |
| Reduced Power (Limp Mode) | AMBER | Engine control system has reduced power to protect components on the MLT 840. | Reduce load, drive slowly to a service area; have system diagnosed. | |
| Fuel Filter / Water Separator | AMBER | Water in fuel filter or restriction detected, affecting fuel delivery to the MLT 840 engine. | Drain water or replace fuel filter element. |
17 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 stop the MLT 840 engine. Check oil level and top off if low; if light persists, inspect oil pump and filter or contact Manitou service.
Engine Overheat
Common causes
- Low coolant level
- Radiator blockage
- Faulty thermostat
What to do
Stop the telehandler and let engine cool. Check coolant reservoir and fill if needed; clean radiator fins from debris on the MLT 840.
Brake System Failure
Common causes
- Brake fluid leak
- Worn brake pads
- Air in hydraulic brake lines
What to do
Do not operate the MLT 840. Check brake fluid level and inspect lines; if needed, bleed brakes or replace pads per Manitou guidelines.
Hydraulic System Malfunction
Common causes
- Low hydraulic oil
- Clogged filter
- Pump failure
What to do
Stop all boom and fork operations. Check hydraulic oil level and add approved fluid; if light remains, replace filter or have pump inspected for the MLT 840.
Overload Warning Active
Common causes
- Lifting beyond rated capacity
- Load shift
- Incorrect stability setup
What to do
Immediately lower the load and retract boom to reduce leverage. Never exceed the MLT 840's rated load chart; reposition load if needed.
Frequently Asked Questions
What does the red master warning light mean on the Manitou MLT 840?
It indicates a critical system fault that requires immediate engine shutdown. Safely stop the telehandler and consult the operator's manual for troubleshooting.
Why is the amber water in fuel light on?
Water has accumulated in the fuel/water separator. Drain the separator bowl by turning the drain valve located under the fuel filter housing on the MLT 840.
How do I reset the service hour meter light?
After performing required maintenance, the light can be reset by a dealer using Manitou diagnostic software or by following the procedure in the MLT 840 service manual.
Can I continue operating if the reduced power light comes on?
The MLT 840 has entered limp mode to prevent damage. Reduce load and travel slowly to a safe area; have the engine and emission systems checked.
What should I do if the hydraulic oil light illuminates while lifting?
Stop lifting immediately and lower the forks. Check hydraulic oil level with the telehandler on level ground and engine off. Add oil if low; if light stays on, contact service.
My MLT 840 won't start and the glow plug light is flashing. What's wrong?
Flashing glow plug light may indicate a preheat system fault. Check the fuse and relay for glow plugs; if issue persists, have the system diagnosed by a Manitou technician.