Believe it or not, thats because your fan motor still has the inertia to make the motor act like a generator and power your car.

It needs a diode to bleed that voltage to ground, sorta like this:

 

I was thinking that the new fan control unit would take care of that. But I definitely need to consider that once I figure this problem out. Thanks.

 

Holy hermaphrodite Jeep PM!

Good luck with this one. Since the 86 CJ would only had a 2.5L or a 4.2L finding a quick fix for this is gonna be tuff. You may want to scrap the current butcher job, and start a new one. There's a couple of place I know of here in Pinellas that prob have some past experience with Jeep Hodgepodge.

 

Dude, isn't this the Jeep that was completely submerged in water at one point?

 

https://www.tamparacing.com/forums/g...ml#post4312507


In other words, yes. .

 

I think his Jeep is pissed because he called a tow truck when he could have drove it out.

 

Guys,

I think I have a short somewhere. I unplugged the ignition switch and tested the positive side of the coil and my test light still lights up. I still haven't bought that multimeter yet (I know, I know, I'm getting one) but I wanted to run this by you guys.

Is my thinking correct that I have a short somewhere? Why would I still be able to light up my test light on the coil wires otherwise?

 

Not that anyone cares but I like to update these when I ask for help.

I had no fire and no fuel. I searched out all the wires and found nothing unusual. So I replaced the ECM ($300 ouch) and it started right up. As far as the fan control unit, I just didn't trust hooking it back through the ignition system. I bought a new rheostat that was much simpler than the one I had before. I hooked one side of the rheostat to the battery (and inserted a 25 amp fuse between them) and the other side of the rheostat to the positive side of the fan. I hooked the negative side of the fan to the negative terminal of the battery. When I turn the Jeep off the fan runs for about 15 seconds before shutting off. I just did not trust connectinig it back through any of the existing circuits. I think this should work out ok.

Now that the All-terrain Politicalmobile is running strong again.... all is right with the world.


PS: Good instincts there Sneakin Deacon. You got me moving in the right direction. Thanks.

 

glad ya got it worked out, just curious though why you used a potentiometer for the fan? i could see you using it if you wanted to control the fan speed, but other then that i dont know...did you like mount it inside your cabin so you could start/stop the fan manually?

if you want something that will be easier on you and not run your fan the entire time, search "Fan Switch" on Summitracing.com. they are pretty cheap, 25-50 dollars for a decent setup and setup within an hour or so for an electrically inclined person. or you could also wire a relay inline with the fan, and pull the 12V signal from something that is hot when the key is on, but itll still run the fan all the time while you drive. just some suggestions though.

 

I used a rheostat that has a probe into the radiator and I can adjust the temperature at which the fan turns on. It was a unit built for just that thing. The other option was to connect it into a circuit tied to the ignition. So it turns on at the temperature desired but it shuts off after the ignition is off. The way I have it now is based solely on the temperature. The fan keeps running until the tempature of the radiator is below the desired setting. Even if the ignition is off the fan keeps running until it cools the radiator below that temperature.

The other unit I had used the ignition as a control source. It was suppose to detect when the ignition was off and turn the fan off when the ignition was off regardless of the temperature. But it was suppose to be powered by a second connection to the battery. Obviously I had some feedback amperage back into that "control" line which blew out my ECM.

I'm not saying the other way wouldn't work and that it wouldn't be ok with a fuse in between but I feel better the way it is now knowing I've had problems with that in the past.