2002 Special PCM vs. 2004 Special PCM - Page 11 - DodgeIntrepid.Net Forums - Dodge Intrepid, Concorde, 300m and Eagle Vision chat

**DrDodge** · 09-06-2012, 01:06 PM

Quote:

Originally Posted by paintballdude05

Personally I don't see why somebody would spend money on an RB1 while you can get something in the aftermarket that is much better in pretty much every respect for the same coin. With that said, I remember reading that the RB1 reads the vehicles VIN and knows if it's a Dodge, Chrysler or Jeep.

correct,,, when I put in my RB4 the first time on m it said Dodge,,, the next time , Chrysler,

**paintballdude05** · 09-06-2012, 06:23 PM

Quote:

Originally Posted by yman4949

I know its been a while but I didn't feel like making a new thread so I decided to just keep this one going! I read on here somewhere about how 2.7 cooling fans kick on at higher temps than the 3.2 and 3.5s. Well even since I swapped my 2.7 pcm for the 2002 special pcm I noticed that the fans will kick on after a while and never shut off. Is there anyway to change the special pcm's fan temp settings to the 2.7's? I just feel like im burning up the fans because when I kick the AC on I hear them kick to high speed and it sounds horrible!

I'm thinking that your problem lies in one of the little known differences in cars with 2.7 vs 3.5 engines. The 3.5l engines have dual speed fans controlled by the PCM depending on a few variables. The 2.7l cars on the other hand mostly came with single speed fans so they were either on or off. So the special PCM could be sending some "slow signals" to the fans yet they can only run one speed.

Quote:

Originally Posted by YesImLDS

Ah I see, so what exactly should my first steps be on getting a 2002 special pcm. I know that I don't specifically need the 3.89 gears but my speedo will be off a little without them and I will probably do that mod sometime later as well.

Find somebody selling a 300M Special PCM with a matching SKIM module and Key. Just so happens I have one for sale that comes with two, programmed but un-cut keys. PM me if your interested.

**peva** · 09-06-2012, 07:01 PM

Quote:

Originally Posted by paintballdude05

I'm thinking that your problem lies in one of the little known differences in cars with 2.7 vs 3.5 engines. The 3.5l engines have dual speed fans controlled by the PCM depending on a few variables. The 2.7l cars on the other hand mostly came with single speed fans so they were either on or off.

You sure about that Steph? That would have to be in the PCM programming if true, because the wiring, though different, gives both setups two speed capability - low speed with the lo-speed relay energized, hi speed with both energized.

There is one difference with the later year non-2.7 fan assemblies - the way they are wired would allow the passenger side fan to be run by itself at hi speed if lo-speed relay off and hi speed relay energized. I've never had it confirmed if the PCM takes advantage of that capability - again, the PCM firmware would determine that.

Quote:

So the special PCM could be sending some "slow signals" to the fans yet they can only run one speed...

If the FSM schematics are right (and I think they are), that isn't correct. The 2.7 fan motors (and also 3.2/3.5 fans on earlier years) each have two windings. Lo speed is one winding powered. Hi speed is both windings powered in parallel.

The other fans achieve lo and hi speed with one winding on each motor. Lo speed is both windings in series (essentially 1/2 system voltage to each motor), hi speed is both windings in parallel (made possible by the two additional relays in the fan assembly)..

yman4949 · 09-06-2012, 10:04 PM

So is there that big of a difference that would cause the fans to run all the time? Ive heard heard my high speed fans kick on with my 2.7 PCM before but they kick on a hell of a lot more with the 02 special PCM and the low speeds never kick off! Is there anything I can do? I just don't know if its good for the fans to be running so much.

**peva** · 09-07-2012, 07:38 AM

Quote:

Originally Posted by yman4949

So is there that big of a difference that would cause the fans to run all the time? Ive heard heard my high speed fans kick on with my 2.7 PCM before but they kick on a hell of a lot more with the 02 special PCM and the low speeds never kick off! Is there anything I can do? I just don't know if its good for the fans to be running so much.

See the fan run schedule on p. 7-31 of the '02 FSM. The lo and hi run speed trip temperatures and forced run times are a bit different (generally lower and longer).