Tranny Swap Year Range Question?

Recently picked up a '98 sport 4.0/aw4/2wd in non running condition (engine issues) and the PO told me they swapped in a '00 or '01 AW4 into it when the original trans went out, they did a horrible job "re wiring" it because it obviously had different connectors for both the NSS and TCC to main harness back by the firewall but for the price I wasn't going to pass on it. I've got the Jeep running now and took it for a spin, it shifts fine up to 3rd but will not go into overdrive, checked the fluid and its good no slips or odd noises. Reverse is fine lights even work. Hooked up my scanner because it of course throws the CEL and it read TCC solenoid shorted to voltage. Other thing I noticed is the TCC connector from the later trans has 2 less wires than the body side, but that was comparing it to my '98 4WD's trans so I'm thinking those 2 could possibly be 4wd related. So my question is will this trans ever work in this Jeep and I just have a wiring issue or should I look for another '98 trans? Any wiring schematics out there I could check out? I did a search but came up empty. Thanks for any info.

That should have just plugged in, so either they were total idiots or it's actually a 97/earlier transmission.

20jeep00 awesome info I'm digging into that now thanks for posting. As far as the PO being an idiot thats most likely true he killed the engine because he drove it with the radiator cap off, not the brightest bulb. So who knows what year it really is and I'll add this after taking another look at the trans, it doesn't have the blue input speed sensor on the drivers side of the case right behind the bell housing like my '98 4wd has, so what year would that make it I'm wondering?

So its looking like its a '97 down tranny, if I was to get a TCM from a '97 (said to solve the CEL issue) would that also solve the not going into overdrive issue as well?

That makes it a 97 and earlier.

Check the part number on the transmission computer, it's bolted to a sheetmetal bracket up between the steering column and the center section o the dash over the gas pedal. It should start with P5604 and have another 4 digits then maybe two letters.

You should be able to stuff a 97 (MUST be a 97, earlier won't work and later is what you already have, I can look the part number up in a bit) TCU into the jeep to make it work right, if his wiring was all up to snuff.

The not going into OD issue is probably because of the stuck solenoid, OD is both solenoids off. If you can track that down and put a 97 TCU in it I think you should be all set.

edit: errr, the torque converter solenoid is stuck, not one of teh shift solenoids, so that may or may not be related, but still needs fixing.

The p/n I got off the TCU is AL158857 there's also a number in the purple sticker area that reads 56041386AA. The unit also has a 98E in the purple area so I'm guessing thats year model most likely. I'll do some calling around tomorrow to locate a '97 TCU and if not I'll just swap a later trans in. Just in case I find one will a '97 TCU from a 4wd will work for the 2wd as well?

The 56041386AA number is the part number - not sure what the other one is, probably a lot code or something. That TCU is definitely the 1998-2001 part number - the one you want is 5602 7951 followed by any two letters or no letters. It'll be in a 1997, but I've seen some 1997s (probably very late builds) that got 1998 TCUs, so verify the part number before buying. In fact I bought a TCU out of a 1997 once hoping to verify that one would fix the no-ISS issue swapping an older trans into a later XJ only to get home and find out I had yet another 1998+ TCU.

edit: and 2wd vs 4wd donors don't matter - the TCU doesn't do anything with the transfer case and fits either package.

Found the correct part number '97 TCM went to plug it in under the dash of the '98 and turns out the plug is just a tad different, all the pins are in the same position it just won't allow you to plug it in. I'm thinking I should just swap the correct trans in now rather than start splicing the '97 connector in also since the trans in it still has an overdrive issue. Did you experience the same issue with the plug when you did yours?

I haven't actually done that test yet - another user reported that it worked, and I and others had been speculating that it would for years, so I took it at face value. Why won't it plug in? AFAIK it's the same connector shells in both units...

I don't know if the overdrive issue is the tranny or the TCU or the wiring at this point in your case... actually, unplug the TCU completely and take it for a drive. See if you have overdrive functionality, you should get 1st in 1-2, 3rd in 3, OD in D. Your torque converter won't lock up at all (since it's 100% electronic hydro system control for that) - actually maybe you're not experiencing torque converter lockup and thinking that you don't have OD because the RPMs aren't dropping enough? Just realized that might be the issue.

kastein said:

I haven't actually done that test yet - another user reported that it worked, and I and others had been speculating that it would for years, so I took it at face value. Why won't it plug in? AFAIK it's the same connector shells in both units...

Click to expand...

The shells are the same in overall size, but the keys are in a different place. I know because I have both a 1997 and a 2001 and had to deal with this issue when I was building new transmission controllers.