2004 chevy cavalier p0480
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go to the underhood fuse block and remove the fan relay. the relay could be bad. swap with another relay in the fuse panel if present.
-the relay should have four pins
-check the connector the relay plugs into....2 female connector pins should have battery power at all times the other 2-one goes to the fan motor, the final goes to the pcm.
-jumper 12 volts to the pin that goes to the fan motor. if the fan works...that wire is good.
so we have checked everything
-power to the relay, power to the fan operates it...checked the relay...if that all is good. the only thing left is bad wiring to the pcm or bad pcm
the pcm wire...the pcm grds the relay to close the relay contacts and operate the fan...so either the wire that the pcm grds is broken or the pcm driver can grd the circuit
-disconnect the pcm connector and ohm check the wire from the relay to the pcm
-shops would turn the relay on via the pcm with a scan tool and then check for grd on the wire...this would verify if the pcm can grd the circuit...without a scan tool you gotta work harder.
-the relay should have four pins
-check the connector the relay plugs into....2 female connector pins should have battery power at all times the other 2-one goes to the fan motor, the final goes to the pcm.
-jumper 12 volts to the pin that goes to the fan motor. if the fan works...that wire is good.
so we have checked everything
-power to the relay, power to the fan operates it...checked the relay...if that all is good. the only thing left is bad wiring to the pcm or bad pcm
the pcm wire...the pcm grds the relay to close the relay contacts and operate the fan...so either the wire that the pcm grds is broken or the pcm driver can grd the circuit
-disconnect the pcm connector and ohm check the wire from the relay to the pcm
-shops would turn the relay on via the pcm with a scan tool and then check for grd on the wire...this would verify if the pcm can grd the circuit...without a scan tool you gotta work harder.
Thread Starter
CF Beginner
Joined: Apr 2018
Posts: 2
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go to the underhood fuse block and remove the fan relay. the relay could be bad. swap with another relay in the fuse panel if present.
-the relay should have four pins
-check the connector the relay plugs into....2 female connector pins should have battery power at all times the other 2-one goes to the fan motor, the final goes to the pcm.
-jumper 12 volts to the pin that goes to the fan motor. if the fan works...that wire is good.
so we have checked everything
-power to the relay, power to the fan operates it...checked the relay...if that all is good. the only thing left is bad wiring to the pcm or bad pcm
the pcm wire...the pcm grds the relay to close the relay contacts and operate the fan...so either the wire that the pcm grds is broken or the pcm driver can grd the circuit
-disconnect the pcm connector and ohm check the wire from the relay to the pcm
-shops would turn the relay on via the pcm with a scan tool and then check for grd on the wire...this would verify if the pcm can grd the circuit...without a scan tool you gotta work harder.
-the relay should have four pins
-check the connector the relay plugs into....2 female connector pins should have battery power at all times the other 2-one goes to the fan motor, the final goes to the pcm.
-jumper 12 volts to the pin that goes to the fan motor. if the fan works...that wire is good.
so we have checked everything
-power to the relay, power to the fan operates it...checked the relay...if that all is good. the only thing left is bad wiring to the pcm or bad pcm
the pcm wire...the pcm grds the relay to close the relay contacts and operate the fan...so either the wire that the pcm grds is broken or the pcm driver can grd the circuit
-disconnect the pcm connector and ohm check the wire from the relay to the pcm
-shops would turn the relay on via the pcm with a scan tool and then check for grd on the wire...this would verify if the pcm can grd the circuit...without a scan tool you gotta work harder.
do you know what wire it is that goes from pcm to relay