quick electric fan question

[novaderrik]

i have swapped an 87 ecm into my 84 T Type, and want to wire up my hayden 16" electric cooling fan to be controlled by the ecm. right now, it's always running when the key is on.
i've got a dark green wire i took out of a Chevy TBI harness with the proper terminal for the ecm that i will be using, i just need to put it into the plug and run the wire out to the relay.
i assume that the ecm controls the grounding of the relay, correct? this makes the most sense to me, because the stock 86/87 has a backup switch in the intake manifold that grounds the relay out (i don't have this, but may add it down the road).

 

[RmvBfrFlght]

Yes, the ECM output grounds the relay coil to enable the fan. It is pin D2 on the ECM. On the stock 86/87 fan this only enabled the low speed. The temperature switch on the engine turned on the high speed of the fan.

There is also a delay relay involved with the high speed fan circuit. But are unreliable and shouldn't be used.

RemoveBeforeFlight

 

[novaderrik]

thank you.
i don't have a low speed/high speed deal- just an aftermarket electric fan that i want to switch with the ecm since i don't have any more holes in the intake for a temp switch.