Cherokee 2WD L6-242 4.0L VIN M FI (1987)
EGR Control Solenoid: Description and Operation
Fuel Pump Relay
This relay is located on the right hand inner fender panel. Relay is supplied battery voltage from the ignition switch and is energized by a ground
provided by the ECU. When the fuel pump relay is energized, voltage is supplied to the fuel pump.
EGR Valve Solenoid
This solenoid is energized by the ECU and controls vacuum to the EGR valve. During engine warm-up, closed or wide open throttle operation or rapid
acceleration or deceleration, the solenoid will be energized, cutting off the vacuum supply to the EGR valve.
Up-Shift Indicator Lamp
This lamp will be illuminated during engine operation according to engine speed and load. The ECU will turn off the the up-shift indicator lamp after
3 to 5 seconds if a gear shift is not performed. A switch located on the transmission will prevent the lamp from being illuminated when transmission is in
high gear. The will be illuminated when the ignition switch is is placed in the on position, but the lamp should turn off as the engine is started.
Ignition Control Module
Depending inputs received, the ECU will trigger the ignition coil by means of the ignition control module.
Injectors
Depending on engine operating conditions provided by the input sensors, the ECU will electronically control the injection duration time. The fuel
injectors are located in the intake manifold.
Latch Relay
This relay is located on the right hand inner fender panel. The ECU will initially energize the latch relay during engine start-up. The relay will remain
energized until 3 to 5 seconds after the engine has been stopped. This allows the ECU to extend the stepper motor for the next engine start-up.
Idle Speed Stepper Motor
The stepper motor is located on the throttle plate assembly. The ECU control idle speed by providing the appropriate voltage signal to extend or
retract the stepper motor plunger to maintain the proper engine idle speed.