Electrical Question..
Thread Starter
Racer
Joined: Jul 2004
Posts: 389
Likes: 2
From: Howard Beach, NY
Electrical Question..
Today I was rewiring my fan setup.. the car came with an after market temp controller and probe. It was running off the 12v switched power under the dash... but the wires didn't like that very much
...so today I used that 12v as the trigger for a relay, and tapped into the 12v from the battery and used a radio shack 30amp relay, with a 20 amp fuse for the fan/o2 sensor.
Is it better to use the relay on the 12v side of the fan? Or have 12v going to the fan all the time and use the relay on the ground side?
...so today I used that 12v as the trigger for a relay, and tapped into the 12v from the battery and used a radio shack 30amp relay, with a 20 amp fuse for the fan/o2 sensor.
Is it better to use the relay on the 12v side of the fan? Or have 12v going to the fan all the time and use the relay on the ground side?
Pro
Joined: May 2002
Posts: 541
Likes: 2
From: Kalama WA
I'm not sure what your question is -but will try to help. If you are setting up a slave relay- run one fused power lead (large enough) to power relay and fan. Use power lead to power one side of the relay coil and one side of the rated contact through the relay. Run other side of contact to the fan power lead. Other side of relay (12v) goes to manual switch (to gnd). Do not try to power the load through the relay coil. It will go up in smoke. Hope this helps or answers your question.
Thread Starter
Racer
Joined: Jul 2004
Posts: 389
Likes: 2
From: Howard Beach, NY
I'm not sure what your question is -but will try to help. If you are setting up a slave relay- run one fused power lead (large enough) to power relay and fan. Use power lead to power one side of the relay coil and one side of the rated contact through the relay. Run other side of contact to the fan power lead. Other side of relay (12v) goes to manual switch (to gnd). Do not try to power the load through the relay coil. It will go up in smoke. Hope this helps or answers your question.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The OEM fan relay switches +12v power from the battery to the fan motor. The other fan motor wire goes to ground. The OEM fan relay has one relay coil wire go to switched 12v and the other coil wire goes to the ECM which grounds the relay coil to turn on the fan motor. The fan motor draws 14 amps, so your 30 amp relay will work fine. I recommend you wire your fan relay the same way the factory wires it.
