Chick-N-Picker

1989 XJ 4.0 auto 91,xxx 4x4

This Jeep is starting to beat me down. Earlier today it was fine. Then I let it sit for an hour or two when I got home.

I went to leave again and I put in D and it acted like it didn't want to go (like it was in 3rd or D) but it did go after I gave it gave it good gas. Shouldn't have done that looking back.

So I went to A stop sign (still in D) this time it acted like it didn't want to go so I did not give heavy gas but instead pulled it into 1-2 and it started off just fine. At about 15-20mph I shifted into 3rd because it never shifted to 2nd.

Once in 3rd it goes fine and then I shift in into D at around 40-45mph. It still goes fine. If I go up a descent hill I will click it into 3rd.

Once I stop I do it all over again. It goes into Reverse just fine. An AW4 with only 91,xxx miles seems likes low miles to fail for these. I'm really worried about it. What does this sound like?

PS:
I did check brake light switch to make sure it wasn't stuck.

I also checked my trams fluid and it was a little below full so I added a half quart with no change.

I also want to say how much I appreciate you guys here helping me through my problems when I have them.

MayerMR

Did you check the level of the fluid?

Chick-N-Picker

yes, I just added that to the update.

Suprmn

I had the same problem. It was my transmission computer. Replaced with another unit and all was good.

Chick-N-Picker

I really pray mine is that simple. I can go to the junk yard and pull 3 or 4 of them.

I'm so worried that I'm actually a little sick. In July I spent $150 fixing VC gasket and a lifter/push rod problem. Then I spent $100+ last week changing brakes and rotors. Now I'm scared this is going to be $300-500 and I just don't have that.

Suprmn

Well, here is how I know it fixed mine. I didnt have time to work on my jeep when it started acting up and it eventually took out 2nd gear and overdrive. I got a replacement transmission, backed out of the garage after putting it in and it was acting the same as the old trans. Trying to start in 2nd gear. Plugged in another trans computer and fixed. Its worth a try.

MayerMR

Where are you located? I have an extra transmission computer from an 87 with the AW4. I'm happy to just send it to you man, I know how it feels when times are tight. I know it works because I took it out of my Jeep to replace it with a TCU from a 1989. Only think I'll say is that you'll prob notice a bit more sluggish shifts bc the 87 computer was...well, sluggish.

Speaking of that...did you check the TCU fuse? It's located under the passenger side dash.

Hit me up if you need the computer.

Basslicks

Try adjusting your TV cable first.

https://www.cherokeeforum.com/f2/free-quick-fix-41821/

After that, check both ends of the transmission shift cable to ensure they're not wallered out or not seated on the "ball joint". You can also adjust this cable as well.

I would check both of these before buying a new TCU.

cruiser54

It could be as simple as a corroded fuse......

Chick-N-Picker

I checked the fuse and it was not blowed or corroded in anyway. I went ahead and checked the lockdown cable and readjusted it. And I checked the cable on the transmission. It was still popped on the joint. It was broke or stretched looking. It was also still on the joint under the shifter.

I checked all the cables under the hood and the only thing that is broke is a piece of plastic that I broke last November that y'all said didn't matter. I believe DFflinstone said he broke it completely off before and no problems.

I drove it again and it starts in 1-2 fine but still doesn't shift into 2nd. I shift it into 3rd and it drives perfect. I shift it into D at 40-45mph. It's almost like when I drove this jeep and my other red one with the TCU unplugged before.

When the jeep is in 1-2 shouldn't it shift into 2nd?

I'm trying to stay calm since I technically can drive it

EZEARL

When in 1-2 and if everything is working as it should it'll shift into 2nd at ~4000rpm.

Chick-N-Picker

Ok. I thought so.

So it's apparently not getting the signal to start in 1 from a stop when in D. It's trying to start in 3rd. And it's apparently not getting the signal to shift to 2nd when in 1-2. So I'm having to shift into 3rd and then D.

Since the transmission is running so strong in R, 1, 3, D. I'm thinking it would run fine in 2nd if it was in 2nd.

Wouldn't this point to the transmission not getting a signal from the TCU? So maybe it's the TCU? I'm thinking out loud.

If it's the solenoids. They are $330 for 3 at O'reillys if I'm looking at the right part. 91,xxx seems low for the AW4 to give problems like this. I may be in trouble this time.

cruiser54

I bet your tCU is bad or has dirty connections.

Have you done Tip 10 on my website?

el diablo loco

This is just a general caveat, but when chasing a similar electrical problem, I had a fuse that "looked" like it was fine, but was really a 90 ohm resistor when I finally put a meter on it. With the voltage levels used in these computer gizmos being 5v or lately(newer stuff than Jeeps) 3.3v, a fuse that is not close to zero ohms can cause the dreaded "unpredictable results". Same as a corroded wire or connection. Probably a lot less likely, but now I meter all of the fuses when I buy them, and usually throw a couple away.

cruiser54

excellent idea.