Radiator cooling fan...
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Joined: May 2016
Posts: 90
Likes: 3
From: Albany Oregon
Radiator cooling fan...
I've only had the 87 for a few weeks and it's never been above 227 degrees. When I picked it up in Idaho I had to get a new radiator installed before my 500 mile trip back to oregon. Radiator had a large hole in it. Anyways the mechanic said my fan wasn't working and created a switch for me to manually turn the fan on to get me home with the idea I'd fix it when I made it home. I still haven't fixed it and just turn the fan on before I drive and flip it off when done. I have a feeling I don't even need the switch because how would that mechanic in Idaho know that it doesn't come on at 227 degrees????
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
The main radiator cooling fan is controlled by the ECM.
If you look at the back side of the driver side black plastic wheel well housing you should see the coolant fan relay.
The relay socket should have a Dark Green/White wire. The ECM grounds that wire to energize the relay which then provides 12 volts to the fan.
The mechanic probably spliced a wire to the Dark Green/White wire to a switch which goes to ground when the switch is turned on.
If you want to see if the ECM can control the fan all you need to do is take a piece of wire and connect Pin A to Pin B on the diagnostic connector located above the drivers right knee.
Turn the ignition on and the fan should run.
The ECM uses the ECT sensor to determine when to turn the fan on and off. It's screwed into the front edge of the intake manifold.
The dash cluster temperature sender is screwed into the head so the two temperatures are close but not the same.
If your AC works it should also turn on the fan when the hi pressure reaches a certain pressure.
Here's a picture of the pin out for the OBD 1 connector.
If you look at the back side of the driver side black plastic wheel well housing you should see the coolant fan relay.
The relay socket should have a Dark Green/White wire. The ECM grounds that wire to energize the relay which then provides 12 volts to the fan.
The mechanic probably spliced a wire to the Dark Green/White wire to a switch which goes to ground when the switch is turned on.
If you want to see if the ECM can control the fan all you need to do is take a piece of wire and connect Pin A to Pin B on the diagnostic connector located above the drivers right knee.
Turn the ignition on and the fan should run.
The ECM uses the ECT sensor to determine when to turn the fan on and off. It's screwed into the front edge of the intake manifold.
The dash cluster temperature sender is screwed into the head so the two temperatures are close but not the same.
If your AC works it should also turn on the fan when the hi pressure reaches a certain pressure.
Here's a picture of the pin out for the OBD 1 connector.
Last edited by Hooked on Vettes; Jul 15, 2016 at 11:38 PM.
