TRANSDUCER 8T5184 - Caterpillar

(5ZL, 7TJ),
5230 (7LL) Excavators;
784B (5RK) Tractors;
785B (6HK),
789B (7EK),
793B (1HL),
793C (4AR) Trucks;
994 (9YF) Wheel LoadersDescription of Change: VIMS can report exhaust system temperatures that differ from the actual exhaust system temperature. Two improvements reduce the causes of temperature errors.
1. A design change to the internal electronics of the buffer makes it easier for the supplier to make a quality sensor. The buffer converts the temperature sensor (thermocouple) output into a PWM (Pulse Width Modulated) signal.2. An improved design in the exhaust riser couplings reduces exhaust leaks that can cause the sensor electronics to fail. The PWM temperature sensor has electronic components that are affected by heat from various sources. As the temperature of the buffer exceeds 250 degrees F., the signal can fault into an FMI 03, 04 or 06. Temperatures in excess of 250 degrees F. can cause a temporary and sometimes permanent sensor failure. A temporary failure will allow the sensor to again work properly as it cools down.Adaptable To: An improvement to the buffer design on the 3E-7826 Exhaust Temperature Sensor will be available in mid-January. This improvement will show as Change - 04 on the sensor.
For engines in 793 trucks (3SJ1-56) and 793B trucks (1HL1-380), install the repair kit for exhaust riser leaks. The parts, installation instructions, warranty claim and parts disposition are described in Caterpillar Service Letter SEBE5869.