Has anyone looked into this? Pulling a heavy load in stop and go traffic, I'd like the ability to override the computer and be able to turn on the fan whenever I want to. If it's hot out, and I'm sitting in traffic with a trailer, on my tow tune, I notice my temps start to slowly climb and I want to have a little bit more control of the temps.

A simple toggle switch is what I had in mind.

 

I would be interested in knowing this myself. Anyone??

 

Easy to rig up.

 

Switch 12v to the fan control wire? Any resistance suggested? diodes?

 

Well, you can switch 12 V to the fan direct, or be a bit more cute and see if you can just trip the existing relay.

 

I don't think it's that simple. The fan isn't just ON or OFF. It's a variable speed fan clutch. I can't find specifics in the service manual, but I'm guessing the signal to the fan is some sort of pulse width signal and wouldn't be simple to control manually.

 

I found this...

 

Can we just throw a square wave at it and pwm it?

 

As David pointed out the PCM uses multiple parameters to control the fan in order to optimize engine cooling. I think I would let the computer do it's job and not try to control it manually. Also remember this is not a standard fan clutch so if you do decide to try manual control I would really understand this circuit before I "rigged up" something. The fan is controlled by a visitronic drive which operates from a 12v PWM signal from the PCM. The PWM signal controls the on-off time of a valve (via a relay) which determines the fan speed. There is also a Hall Effect speed sensor which supplies feedback to the PCM. How does the PCM programming respond to the speed sensor feedback when the fan isn't supposed to be operating?

 

Good point.

 

Dcham etc. are right, think mine (E series) is old fashioned manual and not electronically controlled.

What would be needed is either reprogram PCM, or to spoof it to think it is hotter, or to do a PCM module add on.

Not simple...

Alternative might be to slap on a manual electric fan in front.

 

sorry but same fan cluth in both e and f

 

Durn... here it is I am hoping I get the antique crap that other people sneer at.

 

What's the latest on the fan clutch mod guys? Anybody figure out how to do it? Mine was running all the time so I just disconnected it for the time being. I would like to be able to manually turn it on before towing up a giant hill.

 

If you'll find out what's making it run all the time and fix it the PCM does quite well at running the fan correctly.