88 Iroc with twin fans, I am trying to test the secondary fan with no luck. I remove the wire from the switch and ground it, the relay clicks, but the fan does not come on. I have wired the fans direct and they both run fine. I have tryed 3 different relays, [although none of them new] and they all click but no fan. I have checked the ground to the fan and it is good [both fans are spliced to a common ground, I assume this is factory wiring]. I have even put 12 volts to the plug where the relay plugs in to make sure the wire going to the fan is not cut or damaged, and the fan ran fine. I am out of ideas, any help would be greatly appreciated.

 

On the relay, it clicks, so you are getting ground to it. And you tested the power out to the fan, and that worked. But did you check for the voltage in to the relay?

 

I have four wires to the relay, black with red stripe, green with white stripe, orange, and tan. With the key on, the tan wire has 12.3 volts to it. Thanks.

 

Orange should have 12v+ as well.

green/white is ground that activates the relay - connects to relay coil
tan has 12v with key on - connects to other side of relay coil

Those two "activate" the relay coil.

Orange should have 12v+ always, this comes from fusible link - this is the 12v+ that "feeds" the fan when relay coil activated.

Black/red is the power out to fan. When relay is activated, the power in from orange wire is 'connected' to the black/red wire out to fan.

 

have both fans wired to a separate switch by the battery....so when one fan comes on the other comes on also...used the positive on the battery to the switch with a wire and the power to each fan joined at the switch with a wire (2)....worked great for running fans at the track and cooling while driving

 

I think Newbie's got the right idea. Check for loss of power from the fusible link from the junction area near the battery through the orange wire to the relay

 

Newbie did have the right idea, although I had checked the fusible link already, I failed to check for voltage on the other side of the connector. What I found was a poor connection at that connector, cleaned it up, put it back together, all is well. Tomorrow I will run the car and see if the primary fan comes on, Although I'm not sure what temp it comes on at. Again, thanks for the help.