I need a good "run" power source for my fan relay. I'm looking at the schematic in the FSM, but having trouble coming up with a resonable source. Should I just use my fuel cutoff solenoid wire?

 

Anyone? Class? Anyone?

 

"Buehler"?

 

Exactly! Ben Stein.

 

Anyone out there running electric cooling fans?

 

I don't think I would use the shut off solenoid wire, pretty small. I think I'd run a wire straight from the battery and put a fuse in it.

 

I need a low power switched source for the fan relay. The power for the fan is already wired to the battery (on the contact side of the relay).

 

Yes I am running 2 electric fans,

I see no reason you could not use the fuel solenoid feed for your relay trigger (I used it to control various circuits) but I would insert a 3 amp fuse in-line to protect the circuit in-case the wiring or the relay short out, this way it would not disable your engine if there was a problem and you could still get home.

I would also isolate the feed with a diode and run an additional wire into the cab to an auxiliary powered switch so you could activate the fan with the engine off and ventilate the engine compartment to help combat heat soak.

My 2 fans are connected to my A/C compressor circuit in addition to an override switch.

Jim

 

Thanks Jim. The diode is to control some sort of backflow? Trying to work out in my mind what conditions would call for the diode. Glad to put one on, have used them for other things.

 

I run my rad fan with a switch/relay system and grabbed a switched 12v source (from my home made ignition switch) so when I switch off the motor I won't leave the fan running

 

I wouldn't use the fuel shut off solenoid wire. That wire is used to pull a plunger up with an electro-magnetic solenoid and if you don't keep sufficient amperage and voltage to it your plunger will not pull as far as it should. I would fing an ignition hot on the back of the fuse box and run it off that.

 

The relay's winding will only draw around 75 milliamps. It won't harm the shutoff solenoid's operation at all.

 

Sorry, I misunderstood. Thought you were looking for a place to pull power off.

 

Any dark blue wire under the hood is switched 12 volts. For Mark's purposes there is plenty of capacity.

 

Yes,
You would have the diode between the connection to the fuel shutoff solenoid and the Term. #86 of the fan relay where the axillary fan switch would also be connected.

If you did not have this diode and you had the auxiliary fan switch turned on, it would also feed 12+ back into the circuit (dark blue wire) and supply its own power to energize the Fuel Solenoid and KSB and you would not be able to turn your truck off.

I connect diodes into circuits by insulating the bare leads of a 4-amp axial lead diode with short lengths of colored insulation from wire and then install a male and female insulated spade terminal directly to the leads of the diode followed by clear heat shrink over the entire piece from end to end, now it can be easily added to my circuits by simply plugging them in, I also carry spares already made up, If you do not understand I think I have a picture.

Jim