I have a 1998 Dakota 3.9 auto 2wd and I want to swap in a 5.9 during this quarantine. Easy, right?

If there's a definitive swap thread by all means just yell at me and point me in the right direction. Bolded my questions below.


I know I can use the V6 motor mounts (by trimming one on the block-side) and V6 radiator with V8 hoses. Just going to cut the shroud.

Rocking the 42RE till it goes unless I get a 44/46 with the engine as I plan to swap to a 5 speed later on down the road.

I have read that I have to find a same-year ECU. A 1998 5.9 Dakota ECU... might hard to find. Some forum posts show I can use a 98 5.9 Ram ECU which was much more common... thoughts?

What year range 5.9 harness will be plug and play to the truck, 98-02? Does it have to be from a Dakota or will one from a Ram / Van / Durango work?

Does the V6 harness just unplug and the V8 harness just plug in? Or is there more wiring to it?

 

I'm not sure if a wholesome thread exists or not; I plan to make one while doing mine.

All electronics changed in 2000 to 2001. There is a range there because of how leftovers got used.

All 97-99 used CCM communications buss over 2 wires.
All 01-03 used PCI communications buss over 1 wire.

Yes for 98, a 5.9 Ram PCM will get you very close for a Dakota. You may get an engine or other lights for VIN mismatch to the ABS and CTM units. Unfortunately, most dealers don't have technicians who know how to use the JTEC PCM's, and thus don't know how to flash a new VIN in them. You can also order a Reman PCM from a place like SoloPCM and have them program you a 5.9 PCM using the V6 VIN. [ My V6 already has a reman PCM, we're going to see if it will accept a V8 flash...the ones that started life as a V8 PCM and got flashed to be a V6 PCM will let you switch back since the 7 & 8 fuel injector drivers are already there ]

Yes the wiring harness must be from a Dakota. Durango, Ram, Van, ect will not work. A harness for a 5.2 or 5.9 are the same. [ I went the route of manually adding the wires for 7 & 8 injectors to the V6 harness, but it's not for the faint of heart..you run the risk of de-pinning the whole connector if you aren't quick about it. ]

Replacing the harness is supposed to be very straight forward, but I wouldn't know the truth to that.

Beyond that, there were changes in some inputs through the years. Power steering pressure sensors came and went, HVAC sensor locations have moved around. Some things only existed for 1 year. So you might have to find an exact year-match harness, but i dont know if 98 is one of those years or not (I know my 01 is, that's why i elected to manually add the injector wires). Oxygen sensors are a big one!!! Make sure that matches your truck - either 2 oxygen sensors and 1 cat (49 state) or 4 oxygen sensors and 3 cats (California). For a 98, 49-state was more common. If you have a Cali truck, you can use a 49-state PCM and harness, but you'll need to also get the exhaust system from the same truck. * If you use a RAM PCM, you have to make sure it's ALSO the same config! *

Things you didn't ask but need to know:

The 5.9 is an external balance engine. You will find a chunk of the front balancer missing, and lead slugs welded to the flexplate. The torque converter will bolt up the same.

The radiator and fan shroud are the same, just remove the fan shroud extension thats used for the V6.

Watch the power steering hoses, they may be different lengths. You definitely will need new A/C hoses. You can try to stretch the V6 ones to see if they reach. My 01 is a one-off year, so I'll have no choice.

Technically, you should change front springs, but many people don't and it's fine. The extra 50 pounds or so doesn't seem like much static, but it's amplified over bumps so you may have issues with tires getting into the fender. Worn out front shocks won't help that any, either.

 

Wow, thank you so much for the informational reply! Hope you don't find my questions repetitive!

Just trying to find the most plug and play swap so I can reduce downtime. Dakota parts trucks are pretty plentiful so I was planning on dragging home the best matched donor.

So, realistically I need to find a 97-99 Dakota 2wd with either the 5.2 or 5.9 so the harness is correct. Going with another year or model V8 might lead to other complications with connections and I couldn't use the harness anyways.

I shot SoloPCM a message about reprogramming my V6 ECU for the new motor, I'll see what they say.

With the externally balanced 5.9, that doesn't effect the swap long as I have the 5.9 balancer and flexplate correct?

Thanks again for the help! Thinking this might actually happen. I've done other swaps before but... nothing with a computer. Wires scare me haha

 

That's about where you will be at, yes. 97-99 will get you a usable PCM, but I don't know if any sensor input changed along those years. Note that 97 was also the first year for OBDii, so I'd consider it lowest on desirability for "it was an experimental year" reasons.

They remanufacture PCMs, so likely they'd ship you one and then you send yours back, plus/minus core charge

Right, you need the FP and balancer on the engine. Note that the balancers are known to come apart, so inspect right under the timing pointer on the driver side of the timing cover. When the balancer comes apart, it knocks a hole in the timing cover on the BOTTOM side where you can't see it, and presents as a weird "secret" oil leak. You almost need a dentist mirror. Fortunately, replacement timing covers are available and it doesn't impact anything else. All 3 engines (3.9, 5.2, 5.9) have this problem but it's more prevalent on the 5.9 because of the whole external balance harmonics.

Yea, adding the pins manually is definitely not for you haha. It was a capital female dog, and I deal with electronics for a living.

It's honestly not that bad, since the trucks came with the engine in the first place and thus everything is available and everything fits like it should. This is wayyy different than putting a small block in an S-10, LOL.

The biggest issue is the whole VIN matching thing. And in relative terms, that is an "easy" fix. Ha!

 

so if i have an 2000 dakota v6 manual.
ill be able to swap the 5.2 engine with 1999 dakota v8 4x4 manual ecu in to my 2000 dak v6?