MD6250 Rotary Drill Systems Caterpillar

Electronic Control (Cooling System)

Usage:

In the demand fan system, fan speed and hydraulic fan pump output is directly controlled by the machine ECM. The ECM then sends a proportional signal to the solenoid valve.

As the sensors read temperature higher than targeted, the ECM will send a signal to the solenoid valve to move towards the de-energized position.

Note: If any of the sensors are faulted, or the ECM is not receiving implement oil temperature, the fan may run at max speed. The fan may also run at max speed if the Compressor Discharge Temperature Sensor is disconnected.

Electronic Control Module (ECM)

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Illustration 1	g06411309
(1) J1 Connector (2) J2 Connector

The ECM bases decisions on input information and memory information. After the ECM receives the input and outputs of the ECM are connected to the machine harness by two 70-pin connectors (1) and (2). The inputs and outputs to the ECM can be viewed through the Caterpillar Electronic Technician (Cat ET).

Note: Only the complete ECM is serviceable (no lower-level components). The ECM must be replaced if the ECM is damaged. Replace the ECM if a failure is diagnosed.

Pin Locations

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Table 1
Engine ECM Contact Descriptions
No.	Type	Function
83	Sourcing Driver Return	Engine Left Return
84	Sourcing Driver Supply	Coolant Temp Sensor

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Table 2
Auxiliary Machine Module 2 J2 Contact Descriptions
No.	Type	Function
22	Sourcing Driver Return	Hydraulic Oil Temp.
49	Sourcing Driver Supply	Hydraulic Oil Temp.

Hydraulic Oil Temperature Sensor

The Hydraulic Oil temperature Sensor is located on the hydraulic oil tank. The Hydraulic Oil Temperature Sensor sends a signal to the Auxiliary Machine ECM 2 to give a temperature reading in the cab.