It depends on which emissions package the truck has. 2002 should have been 100% production with 50 state emissions, which would be a cat on each downpipe and a third cat next to the transmission, after the Y pipe.

I don't know where the O2 connectors are on the 4.7. But on the pushrod engines, driver side upstream is attached to the distributor harness along the top of the engine/firewall, driver side downstream is on it's own harness near the transmission sensor harness, passenger upstream and passenger downstream are on the same harness which runs down the spine of the transmission.

 

That makes sense. This is the part I bought - which is not CA compliant (which is why it doesn't have the two extra cats), and apparently compatible for 2000 and 2002 (which is why I bought it). So, I only need the two O2 sensors. The question is, what is the wiring harness and computer expecting? You had me send you a picture of the computer - could you tell if that was a 2000 or 2002 computer? When doing an engine and tranny swap like this, is the wiring harness and computer swapped as well?

Thanks for your help

 

Carid is expensive wow rockauto way lower in price check them out next time.

 

For that part, Carid was among the cheapest, plus they offer military discount of 10%. Rock Auto was cheaper, but shipping was $100. I actually bought the part from Amazon 'used' (open box) with 'minor cosmetic damage' for $158 with free shipping. Can't beat that (assuming it's not beat to hell).

 

I don't like Amazon cant place why I get a low feeling from them Amazon just creeps me out. I think its they mash on any company that sells through them very dictatorial and harsh a number of companies have told me this.

 

you're not screwed at all. just way overprice. like WAYYYYYYYYY overpriced for its shape and condition.
i bought my 99 dak v6 for 1200$ CAD very clean apart from driver side rocker panel ( 3/4 inch rust hole ) a tranny problem and rusted to death manifolds.
others in similar shape were 3000$+ and needed many fix.
for the exhaust , i bet thats where the leak come from. go with ebay headers. way better and cheaper than stock manifold. not worth paying almost double for the oem crappy manifolds. you could go with brand headers that are better than ebay one , but for like 600$+.
they make CA legal headers ( egr or something similar not sure as i live in canada ) for around 300 shipped
if you work on it yourself , fixing your whole truck wont even cost 1000$.

 

Here's an update: BLUF: did bunch of stuff, but now transmission is not shifting past 1st gear and I get a TRANS TEMP light, and new codes thrown!

I took it into the shop where I rented a bay for a couple days. It looks even worse rust-wise from underneath. Here's what I got done:

* Replaced exhaust with Warner bolt-on (SO MUCH QUIETER, and no exhaust smell in the cab)
* Added Denso O2 sensors (Not CA, so just 1 upstream and 1 downstream) (The upstream [F] plug was half melted from resting against the exhaust pipe, but I cleaned it up with a razor blade and it plugs fine)
* Drained and filled rear and front differentials (75W90 Synthetic Gear Oil)
* Drained and filled transfer case (ATF +4)
* Replaced input and output speed sensors (the input speed sensor bolt head was mangled, so I couldn't get it very tight when putting it back on)
* Replaced steering shaft (steering is tighter, but still a little loose)
**** FUN TIME ****
* Drained and filled transmission, replaced filters (here's where the story gets interesting)
-- I dropped the tranny pan, pulled out the old filters, added new ones. The filter grommet was hard to get out, and the new one was even harder to get in. Cleaned the pan, put everything back together.
-- Shop was closing, and this was the last thing I needed to do, so I tried to move the truck out of the shop so I could put the fluid in in the parking lot - so I started the truck, put it in reverse, and nothing, no gear change. I thought, well, probably because there's no fluid in it. Maybe this was a boner move, but I didn't (and don't) know any better.
-- Next day they were open, I go back in and put the fluid in - 4 quarts. I try to shift gears, going through them like my manual says, but no shifting happens. I google, and people say the grommet not being seated properly can cause that problem SO -- I drop the pan again, drain it, and redo the grommet. I decided to use the OLD grommet, since it seemed to fit better than the new one did. When I pulled the filter off, the grommet came with it rather easily, so it probably wasn't seated right. I put everything back together, same filters and same pan gasket, torqued it all up, added fluid (4 quarts), started her up, and she shifted!
-- Now she shifts into reverse and into first, but NO SHIFTING TO SECOND when in drive. I can shift it into 2nd manually, but a few seconds of this and the TRANS TEMP light comes on. I don't really believe it, because the tranny hasn't had time to heat up yet. But, I google it, and people say to check the fluid level - nothing, no mark at all. So I add 2 quarts. Still too low for it being hot. I drive to AAP, add 3 more quarts until it's at the hot level. 9 quarts total, that seems like a lot, but the level is correct now, having checked several times while hot and after driving. But the TRANS TEMP light still comes on, and it doesn't automatically shift into second gear.
-- I pulled codes (I cleared them after I got the shifting working above), thinking they may show something, and there's a whole bunch, some new faces, and some old friends gone. Here they are:
Thanks for any help.

 

P0715: Input/Turbine Speed Sensor Circuit
P0720: Output Speed Sensor Circuit

It doesn't seem to know what speed the transmission is turning. If you changed them, make sure the wiring harnesses are clean.

P1734: [BMW] Pressure Control Solenoid "B" Electrical

This would be the pressure solenoid in the transmission, it's also a transducer that reads the temp. If it's not reading pressure (i.e. clogged) it won't shift until pure pressure forces a shift. Double check ALL your electrical connections, clean them, and since you had the pan off it would have been a good idea to go ahead and put in a pressure solenoid and sensor. Borg Warner is a good brand for this and with the pan dropped, is an easy job so I've read.

P1784: [Ford] Transmission system problems
[Mitsubishi] Gear R incorrect ratio
[Seat/Audi/Volkswagen] Shift up/down Wire Open/Short to Ground

These also point toward bad connections at the harness and/or broken ground wire.

Between the codes for the speed and pressure, that would be why the transmission isn't shifting. I hope you didn't harm the pump by trying to move it (thus engaging the pump) with it being dry. If the pump is leaking, it's not building enough pressure to shift. Although, you said manually shifting into 2nd works so it may be fine.

The number of sensor faults really bugs me, I'm beginning to wonder if you need a new PCM. During some testing when I was putting in cruise control, I put in a PCM from a 1998 Dodge Ram 1500 with a 3.9L into my 1998 Dakota 3.9L. It ran fine, but wouldn't shift out of first, reverse was fine. Transmission controls are a bit more complex than the engine controls.

I'm sorry I'm not much more help than some random ideas, since I have an older model with the magnum series and not the powertech, I have no experience with the 3.7/4.7s, even less with the inner workings of the transmission.

 

Thank you for your thoughts, I will check out the wiring to see anything obvious. I might just have to dump this on CL and eat the cost as an expensive lesson learned.

 

I would never buy any car or truck thats been modified. Way to many demons hiding inside.

My Dakota is modified by me I know it all works and I have kept a list of every change I made to it a diary of mods made.