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Old 05-18-2005, 07:07 PM
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Need electrical help

I need a little electrical help. The electric fan will not kick on or off even with a new relay. I tried 2 or 3. Anyway, the hot wire is hot, the ground wire works, and the other hot line out of the relay is hot all the way to the fan. The green wire when grounded will turn on the fan but it wont turn off becuase it is always grounded.

Now, Im guessing that the coolant switch grounds that green wire to the relay when it reaches a certain temperature to kick on the fan. So, do you think I need a new coolant temp sensor or what? Thats what I'm thinking, what do you all think?

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Old 05-18-2005, 08:05 PM
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Doc here,

The right way to wire the relay should be...
  • Relay Coil power to any 12 ignition fused source (1/2 to 3 amp depending on coil draw)
  • The ground side of the COIL :To the thermal sender
  • The Normally open contact of the relay : to a 12 volt properly fused or linked source direct.
  • The center wiper of the relay to the power of the fan motor.
  • The Ground side of the motor to a direct ground source.

That'll get 'er done!

If it's wired that way, and it still won't function, suspect a bad ground OR a faulty sender...If it was a stock system that ran fine before, I'd suspect the sender..

With it dead cold measure with an ohm meter to ground from the sender wire , it should be infinite..or open...then start the car, as it warms up to temp the reading should drop to 000 if it's working. If it dosn't get a new sender...If it does, look for a bad motor ground.

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Last edited by docvette; 05-18-2005 at 08:11 PM. Reason: afterthought
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Old 05-19-2005, 07:48 PM
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Ok, thanks for the help. I just needed reassurance that I was thinking right, lol.
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