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| Illustration 1 | g02176567 |
Typical ADEM 4 ECM (1) J1 Connector (2) J2 Connector (3) Grounding strap | |
The ECM secures the wiring through the J1 connector (1) and the J2 connector (2) .The connectors are keyed to prevent unintentional swapping of the connectors. The ECM is provided with a grounding strap (3) that must be connected to the vehicle frame. The performance of the ECM is decreased greatly because of noise in the system if the grounding strap is not connected.
Decisions are made by the circuits in the electronic control module. Software in the electronic control module activates the electronic circuits in the appropriate way to operate the machine. Connectors join the harness wiring to the inputs and outputs of the electronic control module through two connectors with 70 contacts. Complete diagnostic codes are available with the Cat ET. The electronic control module uses the data links to communicate and receive machine information.
The electronic control module monitors the condition of the machine for proper system operation. Components sense the condition of the machine. Components then send electrical signals to the inputs of the electronic control module. The electronic control module compares the information from the inputs to the stored information. The electronic control module then decides if outputs should be activated. The activation is performed by sending electrical signals through the electronic circuits to an output.
The inputs and the outputs are protected against internal shorts to the +battery and -battery terminals. However, the inputs and outputs do not function during a short.
Voltage requirements
Steady state
The normal voltage is the system battery voltage that allows the ECM to function properly. The system voltage is the voltage measurement between the +battery and -battery pins on the ECM connector.
Reverse range
The ECM is protected against a reverse system voltage condition. The ECM does not function while a reverse battery voltage is applied.
ECM pull up voltage
An internal pull up voltage is connected to switch and sensor signal input contacts in order to aid in diagnostics. An above normal voltage is internally connected to the ECM signal input circuit through a resistor.
During normal operation, the switch or sensor signal will hold the circuit low or at a certain amplitude. Conditions such as a loss of power to the component, disconnection, or open circuit will allow the voltage to be pulled high by the ECM. The result is an above normal voltage condition at the ECM contact.
ECM pull down voltage
An internal pull down voltage is connected to switch to battery circuits in order to aid in diagnostics.
During normal operation, the switch or sensor signal will hold the circuit high. Conditions such as a loss of power, disconnection, or open circuit will allow the voltage to be pulled down by the ECM. The result is a below normal voltage condition at the ECM contact.
Serial number
The serial number is engraved on the outside of the ECM. The first four numbers are the days and years of the build date. For example, the numbers 1861 would indicate that the ECM was built on day 186 of year 2001.