Sassystang87

Maybe it's the engine maybe it's the trans. .

Okay so here's exactly what we did.
Replaced the trans in my 1999 mustang with one from an 02. Both 3.8l.

The only difference was the speed sensor.

Swapped plugged it in. And proceeded.

Thought all in all was good.

But nope.

Here's the issues. Sometimes it does great. Does awesome if I shift it out 1-2-D. But sometimes it does like 3-4. Doesn't like you stopping the gas revs to 4g bounces.

If you try to accelerate quickly. Same them acts like it's gonna try to kick down a gear. But instead hits four grand bounces. You let of speed up slowly but then it doesn't go into 4 th or od.

When driving at 40 mph I'm running at almost 2g instead of my old 1,200 rpm(or around that range).

No

I am taking it to trans shop tommorow. But I'm looking for solutions else where too.

I know there's a possibility I have to get a different trans. But I figured someone might have some help.

08'MustangDude

It's not the motor...

The 02 (01-03) TRANS is not exactly the same as the 99s.

The one you need 1999 and 2000, PKE AJ1; 9J on the tag.

The 2002 is good for 2001 to 2003, they're PKE BC1, BC2; 1C

They all seem to have the same gear ratio from 1996 to 2004.

In 2003, they put a stronger ring gear in it.

They are electronically controlled, you may need to reset the PCM. I did not see
anywhere where they are adaptive, so that should not be needed. If they index
fluid pressures and clutches, then it needs reset. As the trans age, and the
clutches wear, pressures are adjusted; then it needs reset, as it would be applying
values from the old one.

Sassystang87

Took it to the trans shop. The range sensor is out of wack and the speed sensor isn't reading correctly.

I asked them about setting the pcm. They said it's not an option?

So how do we set the pcm to take this trans and work correctly.

Derf00

Sounds like you have two issues that are not related.
Transmission:
Sometimes the range sensor itself is bad and needs to be replaced. The problem in the video is more severe but you can see how to troubleshoot it.

Speedo:
Your speedo may also be reading incorrectly. This is not directly relevant to the transmission problem but can be deceptive if your think you're going at the speed stated on the Speedo but are actually going slower/faster because the differential gear is different from your car and the donor car.

https://lmr.com/products/94-04-Musta...ter-Correction

Sassystang87

Not the case. My speed sensor is reading correctly. I've always been about 4 mph off. So the speed part isn't off. The sensor it's self isn't corresponding correctly as a whole because we put the 99 sensor to the 02 trans.

Sassystang87

We are swapping stuff out tommorow. Though.

I really would like to keep the newer trans. That's the thing. Mine just quit. No drive gears. Had reverse but no drive.

The main question is.. Is there a way to make this trans work.

The main concern everyone dings around is the location of the speed sensor. The were located in the same spots.

My concern is the neutral safety switch. I can pull up one for a 02 but not a 99.

​​​​

Sassystang87

And yeah I've watched that particular video. Someone didn't double check the range sensor on seeing if it was lined up correctly.

So we gotta check that too.

Sassystang87

No codes are being thrown for this either.

Sassystang87

Put my neutral safety on it from the 99 and the speed sensor for the 02 spliced in and we are running like a champ!