Fan running

[MaxwellSpy]

I have an 87 gt v6. When I turn the key on the fan comes on. I have replaced the fan relay, fan switch, and the temp sensor. I have also checked to make sure someone along the way hadn't hot wired it. Any suggestions as to what might be the issue. Much appreciated

[Slyp]

Check to see if the air conditioner switch is on.  I think the fan turns on when the air is on.

[MaxwellSpy]

It is not. And to make doubly sure I disconnected that whole panel

[Slyp]

If you disconnected the fan switch on the heater panel.  I think the only other way is the temp sensor on the engine.  And you disconnect the heater panel. Try taking the wire off the sensor on the engine block. If it still works there probably is a short some where.

[Slyp]

just in case I misunderstanded you are talking about the radiator fan???/

[MaxwellSpy]

Yes, the rad fan

[GTRS Fiero]

Make sure you unplug the right sensor.  There are 2, I believe.

[MaxwellSpy]

Correct. One for the interior gauge is housed by the coil, the other is by the thermostat housing.

[Slyp]

Have you pulled the coolant fan relay fuse. I would expect it to stop.  Also may try the heater/ac fuse

[MaxwellSpy]

Unplugging the sensor has no effect. Unplugging the fan switch also has no effect. Pulling the fan relay fuse DOES stop the fan.

[Slyp]

Is the relay plugable??

[MaxwellSpy]

It is

[Slyp]

When did this all start to happen.  Have you had the problem from day one.  Was anything done then you started to have the problem.  Just want to make sure we havent overlooked the obvious.  Need someone with a full manual of the car that can make sure there is no other things that could cause this

[fiero4.3L]

Assuming you have no test meter:

Key on, unplug each sensor one at a time. If one stops the fan, the relay input has a short to ground or that sensor/switch is bad/shorted.

Unplug the fan and relay. Key on, lightly touch the socket to the relay to hear/feel the relay click. If there is no click, the relay is likely stuck with the contacts closed.

[Fierofool]

Unplugging the sensor on the corner of the head near the coil only affects the gauge and the temperature light.  It has no input to anything else.

There are two sensors on the right front corner of the lower intake manifold.  One of those is the cold start injector.  It's the one closer to the front of the engine.  The one closer to the thermostat housing and having a mushroom shaped head, is the one for the fan switch. 

Courtesy of Pennocks member fierosound