87 Without B4P Option Fan Control
Thread Starter
Burning Brakes
Joined: Sep 2009
Posts: 1,180
Likes: 2
From: Yes it's hot! Arizona
87 Without B4P Option Fan Control
I have a 1987 without the B4P option and want to lower the temp my fan turns on. I found the wire on the fan relay that will turn the fan on when grounded. Can I install a coolant temp sensor in the head and make a harness to tap into this wire on the relay? Or will this cause problems with the ECM? Mid America Motorworks sells a kit part #611-171 that appears to do just this.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
I have a 1987 without the B4P option and want to lower the temp my fan turns on. I found the wire on the fan relay that will turn the fan on when grounded. Can I install a coolant temp sensor in the head and make a harness to tap into this wire on the relay? Or will this cause problems with the ECM? Mid America Motorworks sells a kit part #611-171 that appears to do just this.
RACE ON!!!
cut&paste below.
Therefore your car does not have the fan switch, which in 1987 would have been in the left head. That hole should have a plug in it. There should be no ground at the relay. The ECM should provide the ground for the primary circuit of the relay to activate the fan.
"CTS", Coolant Temperature Switch? As in (aux) fan switch? If so, I can't see how a secondary ground at the terminal on the relay the ECM grounds to run the fan could harm the ECM. Why a "KIT"??? What happened to good old Yankee engineering? Is there anything to the "kit" other than the switch and a length of wire?
I have a wire connected to terminal "B" of the relay (dark green wire on my '84) that runs through a toggle switch to ground, so I can manually run the fan when I flip the switch. It is great to help cooling between rounds at the track.
RACE ON!!!
