I'm working on an 07 Town and Country, 3.8, Limited I believe the sub model is.

The engine cooling fans are not working. I assumed it might be the relay (given it's a fairly common failure) but first, of course, I had to verify the circuitry was good.

There are four wires to the cooling fan relay. (The relay isn't in the power box, it's mounted with a rivet to the radiator support).
There are two heavier wires, 12 gauge I believe, that are both hot and are the feed side of the circuit, the other two, the control side, are 18 gauge I believe.
1. The orange w/red stripe is full time hot.
2. The dark blue w/ green stripe is hot w/key on and goes to the fans.
3. The black w/dark green stripe is a full time ground.
4. The dark blue w/violet stripe is the "pulse modulation" (I think that's the correct description) ground from the PCM.

I've got power to both hots, ground to the full time ground but the worst possible one to NOT have signal from is the one from the PCM, and, of course, I don't have signal to that one.

So I broke down and borrowed a Hanes manual from the parts store I usually do much of my business with.

The manual does not give an actual "pin out". The only schematic that was of any use at all was the "AC and cooling systems" diagram. The wire colors were correct at the relay but it shows the wire from the relay to the PCM goes first through the power distribution block, according to the diagram anyway, but it shows the dark blue w/violet stripe going into the block and coming back out as a dark brown w/violet stripe and goes directly to the PCM. It doesn't show that wire being fused or anything so I'm not quite sure why it went through at all, much less why it changed color. But...after tearing everything off that was in the way of a clear view and thoroughly searching every plug on the PCM I could NOT find a dark brown w/violet striped wire. I kept thinking "it HAS to be there, I must be missing it. So after pulling every plug and carefully searching for that wire, a total of 5 times, I found there wasn't a dark brown w/violet stripe anywhere on the PCM. Zip, ziltch...nadda.

So if anyone has a "known to be accurate/correct" diagram, would you please check that for me? I don't know if it's a misprint or if they put in the wrong diagram or what the hell's going on. But there isn't a dark brown w/violet striped wire ANYWHERE going into the PCM. It's just not there. Just to be clear, I'm saying "dark brown" because there are many light browns that are identified as such.

I'm not familiar with system. I don't know if it reads off the coolant temp sensor or if there's more than one or where it's/they're at. But, at this point I can't even verify continuity of the control wire from the PCM to the relay. A friend suggested using a multi-meter, probing every wire at the PCM and set the meter to beep when it reads continuity. It seems like a reasonable option as a last resort but I somehow lost all three of my multi-meters and it would be a whole lot faster if I just knew what color that control wire actually was at the PCM. I'm hoping this diagram is just a misprint and someone can tell me what color it is at the PCM.

By the way, I also searched for a dark blue w/violet wire at the PCM, when I couldn't find a brown w/violet, almost as thoroughly as the search for the one shown on the diagram. After already having HOURS into what I've done so far, it may be there and I just missed it.

So, the guy will be bringing the van back in two days (this coming Tuesday), and I have to have my ducks in a row by then.

If anyone has (or has access to) an actual shop manual, I DESPERATELY need to verify the wire color at the PCM.

Also, if anyone is familiar with this vehicle and engine and where temp sensors are and how the system works to make the fans come on and go off, I would be eternally grateful.

I live near Flint, Michigan. It's a major GM town but there are a gob of Mopar minivans and trucks on the road around here. For a bowtie town I'm kind of surprised how many of the the Mopar mini-vans and trucks there are around here. Personally, I'm a Mopar guy but doing repair, I see mostly GM products, some Ford, a few imports and a pretty good amount of Mopars. Most of the Mopars are full size vans, minivans trucks. I actually owned one of the early Mopar minivans, a Plymouth Voyager. But I can't recall the year now.

Thanks in advance,

Wayne

 

My diagram (EBSCO/ARRC) is showing the same brown violet and drk blue violet wires on your 07.

Brown violet at PCM connector C3 pin 6 goes on to the IPM at connector C3 pin 18.

Drk blue violet wire comes out of the IPM (just loops through it) at connector C3 pin 1 goes on to the relay at pin 4.

I also looked at the BBB industries diagrams and they agree with the exception of the dk blue wire from the IPM comes out pin 1 of connector C2 instead of C3.

With time these colors can appear almost black. The PCM needs correct inputs from the AC pressure sensor and the engine coolant temp sensor to turn the fans on. The fans should spin if you disconnect the ECT or within several seconds of turning on the A/C as the pressure sensor detects the correct refrigerant pressure.

BTW-For a long post you've explained everything clearly. Nice work.

 

Raptor, thank you so much for the reply. EXCELLENT info. The funny thing is, I have an account on that too. I never would have guessed that it would have a detailed diagram. It doesn't even give a labor time number for replacing the fan relay. For that reason I never even thought to look in the diagram section. I thought, "why would it be there, they didn't even list a labor time to change the stupid relay!" LOL

Help me out here, which connector is "c3"? Does that mean connector 3? As in third from the top?

Also, I guess I didn't look close enough because I didn't see any numbers on the connector or PCM as to what connector was what. Are there numbers there or do you count from the top working from left to right till you get down to 18? Please forgive my ignorance on this, commonly you can find a "pcm pinout" which clearly identifies what plug and what wire does what. After two hours of searching for a pinout, I just gave up.

Again, thank you so much for your help...and to think I had all that info right here the whole time....LOL For a fairly smart guy I sure can be dumb sometimes!

Wayne

 

The factory shop manual will have the temperatures at which the PCM will send a signal to turn the fans on. They do not operate all the time, only at certain coolant temperatures, which are pretty high (like in excess of 205°). In February, in Flint, Mi, they won't come on much at all. The temperatures also depend on whether the A/C is being used. Your A/C compressor probably won't come on at all this time of year.

The system may be working properly. You didn't say anything about overheating. If it's not overheating, there may be nothing wrong.

 

dcotter, I left the relay unplugged and set a salamander in front of the van while it ran inside the building. I cracked the door so we wouldn't get asphyxiated and watched the temp gauge climb to over three quarters to redline. The computer should have sent signal to that pulse modulated ground wire before it even got hat high. They usually come on just above half in my experience. No signal, plugged it back in, no fans. Shut it off. One good warm day like we're supposed to get next this coming weekend and it'll melt it down. Knowing now that the temp gauge runs off a different sensor than the coolant temp sensor that tells the computer when to turn the fans on, I'm suspecting the latter sensor.

Does anyone know how or IF there's a way to test that with a test light or meter? If it was a GM I'd have a bucket full of them on the shelf, but it's not.

Wayne

 

Whenever the fan doesn't run on past cars I test the in radiator temp switch by bridging over the two contacts, if fan then runs switch gets replaced.
I take it this has been done from the very start.