D50/Power Ram 50 L4-2350cc 2.4L SOHC (1992)
Main Relay (Computer/Fuel System): Description and Operation
Control Relay Location
PURPOSE
The control relay supplies positive current to the EGR and purge solenoids, air flow sensor, ECU, and injectors. The operation of the fuel pump is
controlled by the ECU through the Control Relay.
NOTE: Failure of the control relay may interrupt power supply to the fuel pump, injectors and/or the ECU, resulting in start failure.
LOCATION
The control relay is located in the right kick panel.
OPERATION
While cranking, positive current (supplied by the ignition switch "START" position) flows through coil L2 to close switch S1. As a result, the fuel
pump is energized. Additionally, positive current (supplied by the ignition switch "ON" position) flows through coil L3 to close switch S2. As a
result, positive current is supplied to the ECU, Air Flow Sensor (AFS), injectors, EGR solenoid, Purge Control solenoid and the L1 coil of the S1
switch.
After the engine starts and the key is returned to the "ON" position, the ECU provides the ground to the L1 coil, thus allowing the battery current
to close switch S1. As a result the fuel pump continues to be supplied power, but is now under the full control of the ECU.
In the event of engine stall or other abnormal conditions, the ECU interrupts the ground, opening the L1 coil and interrupting the fuel pump power
circuit.
