[lilshawn]

Related...

I did some work to the front end this summer fixing the ac after a grenaded compressor.... and had removed the front bumper/ac condenser to replace itm... Long story short, keep track of your bolts cause some are long and others, short.... I had to replace the radiator due to a puncture.

I had removed the fan and rad and replaced everything... Came back the next day to a 100% dead battery.

Upon powering up the battery with a charger the fan began running. Stuck relay?

No. Apparently in my reassembly, I splashed coolant on the fan connector... And there was enough conduction from the always hot 12v power lead that powers the fan, to the PWM wire, causing the fan control module to turn on the fan.

Now, the control module is attached to the fan, and if your fan is inop, and at a temp where the fan should turn on, there is somewhere between 6 and 12v on the purple PWM wire, suspect the fan control module.

 

[lilshawn]

New fan and new module combo still inop is concerning. You are going to have to consult the schematic and start following your purple PWM line back... The 12v relay and fan enable line turns on when you turn the AC on so there is always a fallback so that the fan runs 100% when the AC is on. The pwm signal runs the fan at low speeds which is I think where your issue actually lies. If you back probe the pwm while the engine is running and at operating temperature in the fan should be running it should have anywhere between 6 and 12 volts as measured on a standard vom.

 

[lilshawn]

That's typical of FCA parts. If they do a minor revision, they just change the last letter to the next one (AA to AB etc.) If they do a major revision (for instance to have extra holes or shaved down to clear another part on another vehicle... But still works for all the other cars) they'll put out a whole new part number. This is so old stock will still get used up on cars it will still work on, but don't get mixed up with the newer cars where electrically they are the same, but it might not physically fit.

It's possible the controller got modded for higher current and increased MOSFET cooling ... something dumb like that... that it needs for a different vehicle, while still being compatible with the 200. Without disassembling both modules to see the difference it's hard to say. Typically if all the connectors are there and keys properly, and the existing plugs insert... It's usually just fine.

 

[lilshawn]

An Arduino Nano and a high current MOSFET driver and about 10 lines of code could easily replace the module for a grand total of about 10 bucks... It's a matter of 100% stability in the super noisy electrical environment of the car power system that you end up paying for.

That said, Doorman has been making tons of replacement (way improved) parts for Pentastar engines, if it's a common failure issue, they would certainly be making them.