Tranny Issues 97XJ, solenoids, need advice

Okay, here's the breakdown to help everyone out:

1. I have a 97XJ with AW4.
2. When the TCU is plugged in and I have it in automatic, it will go into first but then it does NOT go into second gear.
3. When I unplugged the TCU and run it in limp home mode, all the gears (1,3,4) work fine.
4. I backpinned ? tested the TPS and it is fine
5. I unplugged the harness from the TCU and left the ignition on and ohmed out the three pins that have to do with the solenoids, which on mine are 11 (Solenoid C), 12 (Solenoid A), & 13 (Solenoid B).
6. The results were that 13 & 12 showed 12.5 approx and #11 didn't even register.

Now before I go and order a solenoid for that location, does anyone have any ideas or advice or hints just in case I am missing something.

How can I test the TCU to make sure it is working correctly?

Thanks,

Chris

I´d check the wire and the tranny connector before buying anything. In general, I´ve had more trouble with wires, grounds and connectors than with components. I most always check the wiring first, before replacing anything.

Yep, now that you've found a problem by back pinning the TCU connector, try and measure the resistance downstream on the tranny connector.

Okay, how do I check the downstream connector? Also, how do I check the TCU to make sure it is working correctly?

Also, does the 97 have a inline fuse on the TCU harness? I tried looking for it but couldn't see a fuse or anything to see if it is blown.

Thanks,

Chris

I know you were going to try to avoid dropping the pan but if you want to find out if it's wiring that's open or the solenoid you're going to have to seeing as that's where the wiring ends. When you do that there will be one wire plugged into the solenoid, unplug the wire (it's probably brittle so be careful) then you put one lead of your meter on the tab it was plugged into then the other lead on the case of the solenoid you should read 12 ohms or so.

I don't think the 97's have a fuse but my 88 has one under the passenger side dash (it's a 10amp) I also noticed one in the fuse box labeled trans. So you might check those places.

I find it strange that you only have one gear not working. Usually if a solenoid is out it will effect more than one gear.

Example: the first two solenoids control shifting of 1-4 gears through different combinations of open and closed, the third solenoid controls the torque converter lockup. Like in my case mine would shift from first gear straight to 4th then the torque converter would lock.

On my '90 there's and 8pin connector near the the back of the engine that connects to the trans. Not sure about your '97. Maybe you can follow the cables coming from the drivers side of the trans and see where they go. Also might be good Idea to pick up a manual that has some wiring schematics in it.

I have a 96 cherokee with the 4.0 and aw4. Last year when i was on the highway for about 60 min it would kick out of 4th down to third and sometimes from 3rd down to 2nd. I took it to the steelership because I did not know what was going on. They said my soleniods were bad. Needless to say they wanted $800 for parts and 600 for labor. I bought the parts for $180 at a local tranmission shop and did it my self but it did not help. It still downshifted. A week later I saw a small leak of antifreeze from my waterpump. I changed the waterpump and it fixed the downshifting. My engine and tranny were running hot (I have a tranny cooler) due to the waterpump. The increase in temp caused a decrease in resistance of the soleniods and caused it to down shift (I think). This is just a thought. I am not sure if this is it but my soleniods were not reading the correct resistance according the the steelership but when I took them out and tested them they were fine but I still changed then since I had them out. I hope this helps. I am not the best mechanic so take it for what it is worth.

Wobbles,

It's not that it misses only one gear, it doesn't even shift into second, it just stays in first. This all started happending after I had someone do a transmission flush about a year ago. They used Mercon III like it says in the manual, but I'm still wondering if that had anything to do with it. When it first started happening, it would shift into second but then it would act like it didn't know what to do and shift back down and just rev high.

So basically what it does now is just stay in first and not even think about shifting into second. My engine light burnt out a few months ago but before it did it kept throwing code 45 I believe which was the overdrive solenoid code?

So does anyone know how to check and see if the TCU is blown or not?

Also, I am going to go through every fuse to make sure they are not blown, but how do I check the big fuses in the distributor/fuse engine box? to see if they are good or not?

So as far as I know I need to drop the pan and check the solenoids, but let's say that solenoid C is out, what the heck is that solenoid for? Is that for the torque convertor lock-up and if so, could that cause the Jeep not to kick into second gear, etc?

Thanks,

Chris

I wouldn't think that solenoid "C" would keep it from shifting into second, as far as I know it would just keep the torque converter from locking.


PS- if you do find out it's the solenoids check ebay, I got a set for $5 +shipping from a nice canadian.

Are you saying that in the D position it shifts 1, 3, 4, OD? If so does it skip 2 and 3OD?

That would be really strange becuse the solenoid for 3rd in D is the same one used for 2nd in the 1-2 position. And if 3OD did not happen, then why did 4 OD work, cause it is also the same solenoid?

No, what I am saying is that I plug in the TCU and put it in automatic. It will only stay in first and NOT switch into 2nd, 3rd, or 4th.

So that's where I am confused. From my basic knowledge, it is my understanding that the TCU tells the solenoids when to open or close. And it is my understanding that the TPS tells the TCU when to shift?

If so, I backpinned the TPS and it read what I think it is supposed to and only went up to about 4.5 volts when completely open.

I did NOT backpin the wiring coming from the TCU to the solenoids, all I did was ohm out the pin holes and by doing that found that #11 or solenoid C was not showing anything, but B & A where showing 12.5 each.

So here is where I am trying to reverse engineer this thing to figure what is wrong. First, what would cause it NOT to shift into first? Would it be the TPS (if possibly I read it wrong...can you install the TPS wrong?), the TCU was blown? or is there a fuse that could be blown somewhere that could be causing this.

Is there anything that could have been knocked or blown when they did the trans flush that could have caused this? Oil screen, solenoids blown, etc?

Again, this is a 97 XJ.

Thanks,

Chris

GEAR/ Solenoid 1/ solenoid 2/ solenoid3 TC lock
1 ON OFF
2 ON ON
3 OFF ON
4 OFF OFF

Sounds like S2 is not functioning or the wire running to S2 is open. Probably not shifting into 4 th because the road speed sensor in the tranny is telling the TCU, the vehicle isn´t going fast enough.

Wobbles,

Where did you find this guy on ebay? And what exactly was he selling the solenoids as so I can look it up?

Thanks,

Chris

Okay, last night I backpinned the wires coming off the TCU (plug in this time) with the key on and definitely found that my number 13 pin, which is the last one to the right on the top row (if you are looking at the pins unplugged) is giving me NO ohms at all. The two wires next to it, 11 & 12 are also for solenoids and gave me readings. The number 13 pins turns out to be solenoid "B". So what the heck does solenoid "B" do?

Also, I keep asking this question but no one seems to know how to answer it, but how do you check and see if the TCU (Transmission Computer) is bad?

Thanks,

Chris

I just went through the same thing with my 87 aw4. I swapped/adjusted tps, swapped tcu, swapped solenoids, and when that didn't work, I read my manual. There is a note that says if the speed sensor is not working, it will not shift out of first. Swapped that and now it shifts great!

IIRC it's pin C3. Test resistance to ground (ohms) while driving, you should see the numbers changing (a meter with a needle instead of digital would be better but I saw your other thread). When I tested mine before the swap, there was no change but I don't remember what it read.

The speed sensor (at least on my 87) is behind a bracket for the t-case linkage. Maybe others have found an easier way, but I had to remove that bracket which included removing 2 of the nuts that connect the t-case to the tranny. I dropped the front drive shaft for more space to work. Speed sensor is held on by a 10mm bolt with a little clip.

By the way I have a parts jeep thus all the swapping.

Seymouj,

Thanks for the advice, i will check into that. Meanwhile, check the latest post I just put up with new info and tell me if you are thinking the same thing.

Thanks,

Chris