I just joined the group in the hopes that someone (Thermo?) can help me with a retrofit of a 2000-2004 X type dual cooling fan and PWM fan control unit into my 1996 Dodge Dakota that has a supercharged V8. The dual fan shroud fits my radiator perfectly and I really like the idea of the PWM controller. I have tested it and it runs the fans even though it is one the older style units(2000-2003) that had issues. The fans cool my engine well even here in Florida USA.
I have the 80A power source Brown/Green fed to my factory engine compartment fuse buss panel and the black to a good ground. When I connect the White wire with Green tracer (FCM 15A) to the battery the fans come on, however when I just connect the White with Blue tracer (ECM signal 0-12V) to the battery by itself, nothing happens. If I remember correctly, when I pull the Green tracer the fans slow to a stop, but if I pull both wires (Blue and Green Tracer) together still connected, the fans continue to run….. Strange to me.
What I need help with is knowing what the FCM expects from the Jag engine controller and sensors so that I can make it work correctly on my application. I would like the fans to come to slow speed at a moderate temperature and high speed at a hotter temp, or to come on high speed when the AC system is working.
My PCM and Fuse bus has a relay for an engine cooling fan even though my V8 application didn’t have one originally, this was for the 2.5L option. My SCT programmer person said that he can activate that circuit in my programming and change its temp activation point and its output. The ECU pin is C2 (unused in my application) but I think it is a 5v output not 12v.
What is the best way to make these connections to my factory fan relay, AC system (pressure sensor or clutch), and ECU/PCM to make the Jag FCM work?
Thank you in advance for taking the time to read about my self-induced issue.

 

ctlikon, the fan controller is looking for a pulsed signal from the ECU to tell the fan controller how fast to move the fans. If there is no pulse, the fans are stopped. If there is a short pulse with a lot of off time, then the fans will move slowly. If there is lots of pulses with very little off time, then the fans will run at maximum speed. Unfortunately, there is no easy way to do this unless your Dodge ECU has this function also (most likely not based on its year as it came with a mechanical fan as I recall).

With this being said, you are not out of luck. You can get something like:
Flex-a-lite 30332 Electric Fan Variable Speed Control Module
This would do what you are after and allow you to use the Jaguar fans. This would also remove the weak link (fan controller). You would simply need to find a controller like this that would allow running of 2 fans or getting 2 controllers (which you could then offset slightly to provide even better cooling control, did this idea with my Ford Expedition that I converted over to e-fan, granted, used the factory radiator, just used dual e-fans on the truck).

If you have more questions, let me know.

 

Thanks for the great answer Thermo. What I don't understand is... why does the controller operate the fans when the white wires are connected to the positive terminal of the 12V battery(no pulses)?

 

ctlikon, I would need to look at the diagrams (I'm at work, so I don't have the diagrams in front of me). Odds are, the white wire is the controlling wire and because you are applying 12 VDC there, it is seeing it as many pulses with essentially no off time. This would force the fan to run at max speed.

 

I'll second the Flex-a-Lite controller as out-of-the-box easy.

The fan runs with the signal wires tied to +12 because they are seeing a 'full' signal; basically, you've bypassed the stun setting and gone right to kill...like the PWM sending out a solid "1" to turn on the motors. Since the controller is expecting to see a series of pulses, even on high speed, I'd probably not leave that tied to the +12 for to long. The pass transistor is on a decent heat sink, but it won't last forever.

I have the same basic ECU in my 2000 T&C, with the multi-speed fan...the signals are probably right, but the levels are different; the Chrysler controller (mitsu) is run by a +5v input. Theoretically, I suppose that you could use a level shifter circuit, +5v in, +12V out for the Jag controller, but the pre-built FAL module would be so much easier!

 

Thank you wa3ra, that makes sense and seems to be good advice. After Thermo (Chris) and your recommendations, I have looked at the many PWM controllers out there. Derale 16788 & 16795, Engineered Cooling Products (I like), Painless, Flex-a-lite 31149, and Jegs 52126. I have some time time to research a replacement as the factory unit is working for now but as you say, probably not for long. Thanks again