Engine Control System 1A-5 grounding system or power circuit via transistor or either of the devices listed below. Output driver module (ODM) Quad drive module (QDM) engine fault to the user. In a service factory, 4 pins and 6 pins of DLC (data link connector) can be short to check the DTC while the CHECK ENGINE Lamp (MIL) is flashing. ECM and Components The ECM is designed to offer excellent drivability and fuel economy while achieving exhaust gas emission control requirements. The ECM monitors engine and vehicle functions via various electronic sensors such as CKP (crank position) and VS (vehicle speed) sensors.
Voltages from ECM The ECM supplies reference voltages to various switches and sensors. Resistances of the ECM are very high and this allows the ECM to supply voltages to these devices, and voltages actually applied to circuits are low and even connecting Test Light to individual circuits may fail turn-on. Since the voltmeter normally used in service factories has low input impedance, correct readings may not be obtained. To get accurate readings, a digital voltmeter whose input impedance is 10 M Ω (for example, 5-8840-0366-0) should be used. Input/output devices of the ECM include analog-to- digital converter, signal buffer, counter, and special driver.
By using electronic switches, the ECM controls most system components and turning off a switch closes the ground circuit. These switches are divided into four-switch or seven-switch groups, and the former group is called quad driver module (QDM) and controls up to four output pins respectively while the latter group is called output driver module (ODM) and controls up to seven outputs respectively. Note that all the outputs are necessarily not used in the control. Electrically Erasable Programmable ROM (EEPROM) EEPROM is a permanent memory chip and soldered to the board in the ECM. EEPROM stores program and calibration data, both of which are necessary for the ECM to control the powertrain.
Different from conventional ROMs, EEPROM cannot be replaced with new component. If EEPROM fails, the complete ECM assembly must be replaced with new one. Precautions on ECM Service The ECM is designed to withstand ordinary currents used in operations of a vehicle. Be careful that the circuits must not be overloaded. To test the ECM to check open wiring or short, ECM circuits must be connected to the ground or voltages must not be applied to the ECM. To test ECM circuits, the digital voltmeter 5-8840-0366-0 should always be used. CHECK ENGINE Lamp (MIL) Used as a means of communication between ECM and user usually in the user mode, by light on and off.
If this lamp illuminates during operation, it warns some LNW21ASH000201 1 2 3 4 5 6 7 8 910111213141516 LNW21ASH000301 8 516 1 2 3 4 5 6 7 910111213141