My friend just purchased a 93 350 4x4 cummins and the truck just had the trans rebuilt in it, though the tranny cooler that is under the bed has been by passed, but my friend wants to hook it back up. From what i have gathered by searching on the site is that there is a water to oil cooler/heater canister under the exhaust manifold, another tranny cooler on the drivers side behind the radiator and the third one under the bed which seems to be a factory installed option and not all trucks came with these. The question that he has is that he is not sure where to plug in the wiring harness for the fan portion of the cooler, plumbing the cooler itself is pretty straight forward, but hes not sure about the wiring harness where to connect it to. My guess would be that there is some type of thermostat sensor which would tell the fan to turn on. If anyone could shed some light on this, it would be appreciated. Thans

 

the t stat sensor , if it is an OEM fan, should be mounted on the fan, probably on the intake end. This just needs to have power run to one leg then onto the powering up the fan. All other wires will go to ground. If there is no t stst sensor, just switch it.

 

Could you take a pic of it so that I can see where the factory mounted it? I am about to install a B&M one, and I was going to try to make it look factory.