Integrated Control Relay Module: Description and Operation

PURPOSE
The Integrated Relay Control Module (IRCM) interfaces with the Electronic Control Assembly (ECA) to provide control of the cooling fan, A/C clutch, and fuel pump. The module includes the Electronic Engine Control (EEC) power relay to provide power to the ECA.
These relays are contained in one housing, resulting in longer service life and reduced wiring requirements for operation.

LOCATION
LH shock tower.

CONSTRUCTION
The IRCM has one 24-pin connector. Relays contained in the housing are independent of one another.

OPERATION
The relays contained within the IRCM are interdependent and work with each other. The following describes the different relay functions within the IRCM:

EEC Power Relay
For any other circuit in the IRCM to operate, this circuit must be powered up. This prevents actuators from being turned "ON" without the EEC system having control over them.

Fuel Pump Relay
The fuel pump relay circuit controls the fuel pump. The ECA provides the ground circuit for the primary side of the relay. The secondary side supplies Battery Voltage (B+) to the fuel pump itself.

Electro-Drive Fan Relay
The Electro-Drive Fan (EDF) relay controls the electric cooling fan. The primary control circuit of the EDF relay is normally high (B+). In this state the low speed cooling fan runs continuously. The ECA grounds this circuit, pulling it low near zero volts, to turn the fan "OFF". This "fail safe" is built into the EDF circuit to run the fan anytime the EEC power relay is activated if the ECA should fail open circuit.

High Speed Electro-Drive Fan Relay
The High Speed Electro-Drive Fan (HEDF) circuit operates the high speed electric cooling fan. If the Engine Coolant Temperature (ECT) sensor relays a high temperature or overheat condition to the ECA, it activates the HEDF. In order to turn the high speed cooling fan "ON", the ECA grounds the primary circuit of the HEDF relay. The secondary circuit applies B+ to the cooling fan motor.

Wide Open Throttle A/C Control Relay
This circuit controls the A/C compressor clutch during normal operation. This circuit also disengages the A/C clutch as commanded by the ECA during Wide Open Throttle (WOT) conditions. This solid state relay has two control circuits. One is used to engage the A/C clutch upon demand from the vehicle operator and the A/C cycling pressure switch. The other control is used to disengage the clutch upon command from the ECA.

Power Ground
This circuit provides the IRCM with a ground source for operating various controls. The circuit uses one pin that goes to the battery negative terminal.