HOSE AS 2751367 - Caterpillar

Electronic Control Module (ECM)
Illustration 1 g03796252
(1) Connector view from ECM side
(2) Connector view from harness side The Engine ECM bases decisions on input information and memory information. After the Engine receives the input information, the ECM sends a corresponding response to the outputs. The inputs and outputs of the ECM are connected to the machine harness by two 86 contact connectors (J1 and J2). The inputs and outputs to the ECM can be viewed through the Caterpillar Electronic Technician (Cat ET).In most instances when a diagnostic code or an event code is activated, the ECM is the least likely cause of the problem. When an ECM is suspected of failure, always ensure that the latest software is flashed on the ECM. Verify that the ECM connections are secure. Then, verify that the problem is still active before replacing an ECMNote: Only the complete ECM is serviced (no lower levels components). The ECM must be replaced if the ECM is damaged. Replace the ECM if a failure is diagnosed.Pin Locations
Table 1
Engine ECM Connector J1 Contact Descriptions
No. Type Function
4 PWM Output Fan Solenoid (+)
7 2A ON/OFF Fan Block Solenoid (Cold Start)
12 Sourcing Driver Return Fan Solenoid (-)
17 CAN (C) Data Link (+) Emissions
18 CAN (C) Data Link (-) Emissions
20 Cat Data Link (+) Data Link
25 CAN (A) Data Link (+) Machine CAN A HIGH
26 CAN (A) Data Link (-) Machine CAN A LOW
28 Cat Data Link (-) Data Link
49 Sourcing Driver Return Fan Bypass Driver Return
54 Sourcing Driver Return Reversing Fan Driver Return
69 Key Switch Input Key Switch
73 PWM Output Reversing Fan Solenoid Driver
81 Battery Return Battery Negative
83 Battery Return Battery Negative
84 Battery Power Input Battery Positive
86 Battery Power Input Battery Positive Outputs
The ECMs respond to decisions by sending electrical signals to the outputs. The outputs can create an action or the outputs can provide information to the operator or the service technician.Solenoids
Illustration 2 g02747758
Typical example of a solenoid valve
(1) Pin 1
(2) Pin 2 Demand Fan Proportional Solenoid Valve
The demand fan proportional solenoid valve is located on the bottom side of the fan motor housing. The demand fan proportional solenoid valve receives a variable PWM signal from the Engine ECM based on the machine temperature sensor inputs.Demand Fan Reversing Solenoid Valve
The demand fan reversing solenoid valve is located on the top side of the fan motor housing. The demand fan reversing solenoid can be operated manually or automatically. In manual mode, the operator chooses when to reverse the fan by pressing the reversing fan button on the keypad in the cab. In automatic mode the ECM will reverse the fan for 10 seconds every 30 minutes.High Altitude Cold Start Solenoid Valve
The high altitude cold start valve enables the unloading of the brake, fan, charge pump during cold/high altitude engine start conditions to facilitate easier starting due to reduced engine load.Data Link
Cat Data Link
The Cat Data Link is an input/output of the ECM. The data link uses the connector for the service port in order to communicate with the Caterpillar Electronic Technician. A