Hello, thanks in advance for any assistance.

Okay so I have a 99 3.9 l Dodge Dakota two-wheel drive, with a broken transmission no reverse and some pretty big chunks of metal I pulled out. I also have a 2000 3.9 l Dodge Dakota two wheel drive, with a blown head gasket and a good transmission..

So choosing the lesser of two evils, I pulled the transmission from the 2000 and put it in the 99. Everything bolted up fine. Wire connections all compatible. Test drive no overdrive switching no fourth gear and trans temp light comes on after one mile. So to remedy this I also swapped the PCM from the 2000 and put it in the 99. And bam! Overdrive working, over drive switch works, shifts into fourth gear, no problem hooking up and unlocking as it should, everything with the trans seems to be working normal.

Except for one problem, p1491 radiator fan relay code. I can't check the circuit because there isn't one. The 99 has never had an electric radiator fan. No pigtail from the wire bundle going across the front of the truck like the 2000..
So I have three questions...

Can I bypass the circuit and trick the PCM into thinking it's all good?

Will the p1491 code cause a limp mode of any kind?

If I were to install the radiator from the 2000 into the 99 how and where would I form the circuit?

Thanks again....

 

The easiest way would be to reprogram the PCM to no longer recognize the fan. Go to the HP Tuners website and see if it can talk to your truck. If it can, you can either buy a copy or see if anyone in your area programs with it. It should be able to turn the fan off in the PCM for you. The alternative would be to get into the manual for the 2000 model and see where the fan plugs into the PCM, and buy a pigtail to install. Third alternative, you could move that wire pair from the PCM to the fan on the 2000 to the 1999 model, but at some point you'd need to put it back if you plan to do anything with the 2000 model. Repinning a PCM harness connector is not difficult to do, but it does require that you be comfortable with the idea of messing with the wiring harness which will be akin to untangling the lines from several fishing reels as pulling a cable pair out of a wiring harness means pulling the harness apart from one end to the other, retrieving a cable pair never meant to be separated again, and taping it all back together again. This would also be the cheapest way to go, since you already have the fan and cabling on the 2000 model. You could probably just move the entire engine harness, but doing this might open a new can of worms that just retrieving the cable pair would not open. Really though, I'd suggest getting the fan and cable pair from a junkyard truck since you wouldn't have to worry about the harness's condition afterwards, nor would you have to be careful about removing it to get the cable pair. You'd also be able to figure out how to get the screwdriver into the PCM plug to remove the cable pair without risking damage to the ones you have at home.

 

Or, you could take the electronics out of the 99 trans, install them in the current trans, and put the correct PCM back in your truck.......

 

Thanx for the response!
Are you talking external electronics or internal electronics, Hey You?
I think I'd be more comfortable scabbing in a simple circuit, as the '99 has the relay in the power dist center (i think that's what it's called... Engine comp fuse block) than i would dropping the pan to access internal electronics. External electronics heck ya! Although, I'm not sure why but i have to say the '99 with '00 trans and pcm is running exceptionally well considering the 330,515 miles the motor has on it!

 

Oh and what about the check engine light and code.... Does it set pcm to limp mode or something similar?

 

Oh and what about the check engine light and code.... Does it set pcm to limp mode or something similar?

 

Internal trans electronics. Governor pressure sensor and solenoid, and the TCC and O/D solenoid set. (solenoids are the same, connector for them is different between the years)

Trans temp light being on will disable O/D.....

 

Agree with HeyYou. The trans solenoids are EASY to replace. Will cost you some trans fluid, the trans filter, a valvebody gasket, and I think that's it. You don't have to unplug anything - it's all one harness. Just remove the solenoid pack, pull the connector out of the case (it's O-ringed), put the 99 connector in the case (make sure O-ring seats), bolt the solenoids in.

The shift shaft I think has to be undone, not sure if the TV cable has to be unhooked.

 

Thanks again guys! That doesn't sound all that bad.

So the solo p1491 code shouldn't effect the drivability? The trans temp code was from mismatched pcm and trans.
Not noticing any ill effects from the current config...

 

So, these are the chunks i fished out of the '99 trans that didn't have reverse! Kinda looks like it was a one piece ring at one point .... Any ideas where it's from?? A few pieces were in the pan, the others i took my magnet on a stick and poked around up and towards the back to fish these out. Might still be one more in there ....