There is no possible way that any system using anything currently manufactured by derale works. I tried all of the derale solutions and none of them were strong enough to cool the truck off when towing. I made a custom shroud also. They probably just copied my design...which doesn't work. To end any argument about whether or not to install an electric fan, just find the CFM of the fan system and compare it to the 10,000CFM MINIMUM of the v8 stock fan and then decide if you still want to do that mod. I still have my dual 70A main fan relays, dual 40A front fan relays and fan controller(s) installed in my truck with the two temp senders. They just sit there to remind me of the hell I went through trying to get electric fans to work as well as the stock fan.
For anyone interested in this mod, you will need the most powerful electric 15" fans out there- each one pulls 65A, then you will additionally need the most powerful 12" fans out there. Each one pulls 35A. When both fans on both banks are on, you are pulling 200A constant from the electrical system. The alternator can't handle that and will burn out in 1 month (guess how I know), so now you need a new alternator with better current capacity. But wait! how do you get an accurate read on the engine coolant temp at the radiator? Omron makes several 24V 1/32 DIN PID controllers that can mount in the pocket underneath an aftermarket deck with a 12-24V boost converter to power it. Just get the appropriate K-type probe and drill a hole in your radiator top to mount it. Then, figure out how to program the PID to turn on the fan banks in sequence to have low, med, high and tow modes and also a river crossing mode where both banks are off. "But I have an air conditioner" you say- well fine, just make and inductive pickup using a TIP transistor which indicates when the AC circuit is powered on and sends that signal to the PID to engage low-constant mode. That is, unless you are towing... In which case you will need to intercept values on the CANBUS by creating a network node out of an arduino to indicate the calculated load on the engine and feed that data in hexadecimal to the PID using a network bridge to allow the PID to alter its progressive values for the fan boost converter. "What fan boost converter?" You say. Well... since the low, med and high modes are not powerful enough to cool the engine, you came up with a solution that you also designed specifically for "towing mode" which is wired in parallel to the existing fan circuit using high current diodes to OR both the existing current from the 75A relays and the current from the boost converter to create an even more powerful fan which operates in what I like to call the "overload" or "emergency" mode. This mode engages everything possible to attempt to cool the engine when it is still overheating.
I did all that. None of the solutions worked as well as the Toyota-designed belt driven fan in all cases.
