Can you guys tell me where I can connect a switch to manually turn the engine cooling fans on when the truck isn't running? I did a test the other day & found the truck has a fail-safe, I pulled the #70 relay & ran the truck--with relay out fans run on high speed. Connect at sensor--wherever that is?

 

I'm new to the truck world. Why do you want to manually run you rad fans?

 

You would need to look at the wiring diagram or the case of the relay, find out which wire the PCM grounds to activate the relay and connect a switch from that to ground. But the PCM may not like that, it may think its a short and set a code or you may get a fan rationality code. Both would give you a CEL on.

 

Probably to cool the engine for drag racing.

 

Yes, I wondered about that, (pcm/short), maybe with just key on-engine off if wouldn't. Have to do some checking with the multimeter I guess, just kinda scared I'll mess something up. That's why I thought I'd ask you guys.