INSTALLATION AR-TRUCK 1493009 - Caterpillar

ECM Pull Down Voltage
In order to aid in diagnostics of electrical circuits that are controlled by the ECM, an internal "pull down voltage" is connected to ECM switch to battery type input circuits. During normal operation, the switch contacts that are allowing the connection to a voltage source will hold the circuit high. When circuit conditions such as a loss of power to the switch supply voltage, a disconnection in the switch circuit or an open circuit will allow the circuit to be pulled low by the ECM pull down voltage. This condition will result in a below normal voltage condition at the ECM contact. As a result, the ECM will activate an FMI 04 (voltage below normal) diagnostic code for the affected circuit. Pin Locations
Table 1
Implement ECM Contact Description J1 Contact Descriptions(1)
No.(2) Type Function
10 CAN C Data Link - CAN C Data Link -
13 Battery Return Battery -
20 CAN C Data Link + CAN C Data Link +
22 Analog Input Hydraulic Oil Temperature Sensor
23 Battery Return Battery -
31 Battery Power Input Battery +
38 Battery Power Input Battery +
39 Battery Power Input Battery +
47 Battery Power Input Battery +
57 Battery Return Battery -
70 Battery Return Battery -
(1) Contacts that are not listed are not used.
(2) The connector contacts that are not listed are not used.
Table 2
Implement ECM Contact Description J2(1)
No.(2) Type Function
22 Return Sensor / Driver Return
64 CAN Data Link + CAN B Data Link +
65 CAN Data Link - CAN B Data Link -
67 CAN Data Link + CAN A Data Link +
68 CAN Data Link - CAN A Data Link -
(1) The ECM responds to an active input only when all of the necessary conditions are satisfied.
(2) The connector contacts that are not listed are not used.Inputs
The machine has several different types of input devices. The ECM receives machine status information from the input devices and determines the correct output action that is needed in order to control machine operations based on memory and software parameters. The machine utilizes the following types of inputs: switch type and sensor type. Switches provide signals to the switch inputs of the ECM. The possible outputs of a switch are listed: an open signal, a grounded signal and + battery signal. Sensors provide an electrical signal to the ECM that constantly changes. The sensor input to the ECM can be one of several different types of electrical signals such as: pulse width modulated (PWM) signals, voltage signals and frequency input signals. Each possible input to the ECM is listed in the tables for the 70-pin connectors.Inputs provide information to the ECM in the form of sensors or switches.Sensors
Sensors provide information to the ECM about the intent of the operator or changing conditions. The sensor signal changes proportionally to the changing of operator input or changing conditions. The following types of sensor signals are used by the ECM.Frequency - The sensor produces a signal and the frequency (Hz) varies as the condition changes.Pulse width modulated - The sensor produces a signal. The duty cycle of