'86 Vette Cooling Fan

I'm helping a friend get his car on the road and hit a road block. Here's what I tested with him tonight and what I know.

Power probed the fan while disconnected and it turns on.

The replay works. I can bypass the relay and turn the fans on.

I'm getting power in all the right places.

The odd part is that Mitchell says the coolant temp switch turns the fan on at 238* but I can't find the switch in any diagrams. I only see ect sensors.

From looking at parts pics, we found the switch on the block. One wire pull down. When I bypass to ground the fans don't come on.

I'm not sure what this is missing to work?

He is planning on running a toggle switch at the relay for now but would like it working properly.

What would you test next?



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what happens if you ground the green and white wire at the ecm? they should turn on...

www.corvetteforum.com/forums/c4-tech-per...auge-inaccurate.html

from the sound of it there is 2 sensors

Yes, they did when I tried that. Im wondering if the part that I thought was the temp switch isn't. It had 5v on it unplugged and the fans didn't turn on when I grounded it.

cheryl hartkorn wrote: what happens if you ground the green and white wire at the ecm? they should turn on...

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I takes to the owner this morning and he said that the sensor in the picture Cheryl sent is not in his car and has a plug in it's place with the wire just sitting there.

The sensor we were messing with the other night was a knock sensor.

I believe he said he grounded the wire that was just sitting there and the fan didn't turn on. I'd have to look at it again to see if it's a negative coefficient sensor or not.

He ended up running a switch in the cabin for now.

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If you can't find the switch you can buy switch adaptors that fit in either the top radiator hose or the heater (by-pass) hose.