The logic module uses this relay to disengage the air conditioning compressor clutch when the throttle position is at wide-open (WOT). This provides maximum engine output when it is required. The clutch is allowed to engage again when the throttle is not at WOT. It is also used to keep the A/C clutch disengaged for 10 seconds after engine startup, allowing the logic module to determine what the target AIS motor setting should be for idle. Lastly, it is used to disengage the clutch if the engine speed drops below 500 rpm, to try and keep the engine from stalling.
When the logic module is turning on or off the relay, it momentarily checks the output of the relay/solenoid driver to see if it is responding the way it should. If it does not see about 0V when on (open circuit) or 12V when off (short circuit), a fault code 33 is stored. Any vehicle not equipped with air conditioning may receive this code, in which case it should be ignored.
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Copyright © 1996-2003 Russ W. Knize.