SY365 Excavator T4 Emission – Engine Torque Limitation

Item	Details
Fault Type	Electrical Fault
Equipment Code	SY036MBK00508
Model	SY365
Business Unit	Heavy Machinery Business Unit
Product Group	28/Excavator/Excavator
Operating Hours	2336 H
Shutdown Fault	No
Location	United States of America
Public Status	Display
Service Order	—

Fault Description

Learn to use Cummins service software for troubleshooting.

Fault Phenomenon

Engine torque limited, machine operation slow. Red and yellow engine fault lights on display. DEF level shows 100%.

Fault Cause

Defective 3-in-1 sensor/module on the urea tank.

Troubleshooting Process

1. Parked the machine on level ground upon arrival.
2. Checked engine oil, coolant and hydraulic oil; all at normal levels.
3. Test run showed red and yellow engine alarms on display, no acceleration, and DEF level reading 100%.
4. Found actual DEF level was not 100%, preliminarily judging abnormal feedback from the urea tank 3-in-1 unit.
5. Measured voltage of the 3-in-1 module on urea line as 23.5V, within normal range.
6. Performed urea pump test, DPF load check and SCR test via Cummins software; all normal. Read ECM fault codes: 3868 / 4677 / 4572 / 3714 / 3712, all pointing to the urea tank 3-in-1 unit. Since voltage was normal and machine had been idle for a long time, concluded the 3-in-1 unit was faulty.
7. No spare part on site. Swapped the 3-in-1 unit from another machine (same connectors, cooling pipes and DEF fittings) for testing; fault eliminated.
8. Replaced with a new 3-in-1 assembly the next day; fault permanently resolved.

Troubleshooting Experience

1. Qualified DEF urea solution must be used at customer site.
2. Pay attention to the shelf life of urea during long-term storage.