Quick! Looking for 20A or better Key on power source

[94Blue302GT]

I'm installing an electric fan and need a key on source. Any recommendations?
I have area underneath the steering column undone so i can see the ignition module, but i don't know which wire, and i don't know if there might be something better in the engine bay.
Gotta get it done today, thanks!
Lee

 

[94Blue302GT]

No good power sources on the vehicle eh?
Well, i'm not going to have a constant switch on the thing!

 

[Blee1099]

There are plenty of 20 amp fusable links under the hood, not sure if they are active only when the key is in the ON position or not. The number (3) Maxi fuse which controls the fuel system & anti-theft system, (7) Maxi fuse which is the Trailer park LP & trailer stop LP lights, (11) Maxi Fusethe PCM Memory & Horn or (4) Minifuse is the 4WD system and (11) maxi fuse is the HEGO system (heated exhsust gas oxygen) system.

 

[94Blue302GT]

ok, but wouldn't i need an open one that turned on with key, and then put in a new line for the fan? I have a relay they gave me, but it's only a relaty for the thermostat. So, i'm trying to run it out of that box, but only when the key is on, which is the tricky part.

 

[Blee1099]

Get a 12 volt probe or a multimeter and check all of those mentioned circuits. If you get power to one side of the circuit then its controlled by the ignition. If I wasn't so lazy I would go probe the circuits.

 

[DeRocha]

ok, but wouldn't i need an open one that turned on with key, and then put in a new line for the fan? I have a relay they gave me, but it's only a relaty for the thermostat. So, i'm trying to run it out of that box, but only when the key is on, which is the tricky part.

Do you have a wiring diagram? It seams confusing the way you're describing it... A relay is normaly used to switch high power (which the thermostat isn't). I would have expected the fan to be grounded and it's power wire connected to the load side of the relay with the other side connected to a fused source directly to the battery, fender solenod, or distribution box. The other 2 wires on the relay would be for ground and the trigger voltage from the thermostat... ie when the thermostat reached it set point it would send 12v to the relay which would connect the battery to the fan....

 

[IAmTodd]

I would use a relay and not pull it directly from some random wire you spliced off of.

 

[94Blue302GT]

Ok, i found a 5 prong relay (bosch) that i had leftover from pulling the ABS off of my stang.
Where was that site for the relays and such? This way I can splice off of anything, right?

The thermostat relay i was refering too just kicks the fan on at a certain temperature. BUT, That means if i wire it with just that thermostat (which only has power from the battery, no acc) then it could stay on after I shut the truck off.

 

[94Blue302GT]

Ok, i think i figured it out... Let me know if this sounds right:
My constant 12v to the 30 prong.
87a is capped off
87 is connected to my thermostat
85 recieves power from the ACC-ON
86 is grounded out.

I may have 85 and 86 reversed, check that for me. OH, and for the ACC-ON is it ok to splice into the ignition module, or will that just end up lessening the power for something else?

 

[94Blue302GT]

Oh, AND...
I should be able to splice into one of the wires turning on one of the other relays in the fuse box as well, correct? I don't have an owners manual, anyone tell me which one's to try out first?
None of the empty fuse spots turned on with the ignition.

 

[DeRocha]

...
The thermostat relay i was refering too just kicks the fan on at a certain temperature. BUT, That means if i wire it with just that thermostat (which only has power from the battery, no acc) then it could stay on after I shut the truck off.

Correct and that is how many vehicles work.. The fan will continue to cool the engine until the thermostat drops below its set point. At work during the summer I can hear the fans running on some vehicles for a few minutes after the engine is off.

Did you get any install instructions with the fan? What is the power rating of the thermo switch?

 

[94Blue302GT]

The thermo switch is rated at 20A supposedly. I'm hoping it's enough. Should be, it's a more basic fan really, otherwise i could use that to turn the relay on and get 30 amps.