New to owning a Jeep and need some help!

[mwheeler84]

Ok so I just picked up a 1993 Jeep Grand Cherokee Laredo, straight 6, 4.0l. When we bought it I believe it had been sitting a while. We've cleaned it up vacuumed it out and what not. So here's my problem:

Putting it in drive and going to accelerate the rpm's jump up to between 1600-2000 rpm before it will start to move even if I punch it. If we drop it down to 1st gear it seems to do the same thing. It's really slow at acceleration but to me it seems to get a little better after driving it for a bit. It does have an exhaust leak at the exhaust/intake manifold gasket which has not been fixed yet. We have replaced the transmission filter and dumped 32 oz of Lucas gas treatment in a full tank of gas. We were hoping that the filter would fix the problem but it is still the same.

If I put it in reverse it takes right off, no hesitation at all. I do live in cold Iowa and I'm not sure if it's just the cold but dad doesn't seem to think so.

Also, when we were changing the trans filter we noticed there was a sensor that plugged in somewhere on the transmission where the transmission pan was at the had 3 wires that were exposed. There was also another plug/sensor that wasn't plugged in to anything and we think that might have been the o/d sensor. The o/d off button doesn't seem to work by the way. Any ideas what those sensor's are down there?

Any advise would be greatly appreciated. Thanks in advance!

Misty

[4.3LXJ]

Do you have all four gears?

[mwheeler84]

I think so but how can I tell? I don't feel it shift at all except when I put it in R or D from Park. Also it's only 2wd.

[4.3LXJ]

I would suggest seeing if you can feel it shift and watching your tach while you accelerate. It almost sounds like you only have one gear. Those wires might be for the shift solenoids

[mwheeler84]

I have watched the tach and it jumps up to 2k rpm before it starts to move. When you take your foot off the brake at a stop it doesn't move forward at all. Once it gets moving the acceleration is fine. I can get up to highway speeds no problem after getting it to start moving. I've looked at a lot of things and think maybe tps or maybe could it be the exhaust leak... not getting enough air. You can hear the leak when you accelerate from stop as it's very loud and throaty.

[mwheeler84]

Ok so we just took it for a drive to see what was happening when it is "supposed" to be shifting. Usually in a non-broken vehicle you would see the rpms drop a little when it shifts. Getting on the freeway in drive the rpm's never shifted down. They just kept rising. When putting it in 1st and manually shifting to 2nd the rpm's never dropped. The only time the rpm's dropped and you could feel it shift is when manually shifting from 2nd to drive. Soooo my question now is... could those exposed wires if they are the shift solenoid could that cause the vehicle to not shift or does it sound like my tranny is shot?

[cantab27]

tps ...................

[mwheeler84]

Alright so I think I just solved my problem! LOL. I was reading on another thread about how to check the codes manually and I am throwing codes 23, 22, 21 which are all the solenoids!

[4.3LXJ]

Codes was my next question ...

[mwheeler84]

Ok so could there be a fuse that would make all 3 of the solenoids throw codes or is it common for all 3 to go bad at once? Also, what is the damage to the vehicle if I continue to drive it without replacing the solenoids?

[bigjim350]

Sounds like the wiring in your tranny is messed up. And it would be a bad idea to keep driving it like it is. If its not shifting its running very high rpms which can ruin the trans and also run a very high risk of over heating the engine.

[bluedragon436]

Id say look into seeing if you can find a new trans out in the JY if you can't afford a rebuild.... or heck if you can source the parts find a trans and other parts needed you can convert it over to 4WD using JY parts.... if you can source the parts and have the time to be able to put into swapping/upgrading your ride...

[4.3LXJ]

No fuse really. You can check them, but those solenoids are controlled by the transmission control module, which is working if it is throwing codes at you. Tony (Mudderoy) replaced his. It is not hard. Since you have had the pan off, that is most of the work. Make sure all the wires are intact while you are at it.

[mwheeler84]

4.3LXJ .... ok when I was up under the jeep changing the filter before we took the transmission pan off we seen this plug that had 3 exposed wires coming off of it. As your laying on your back looking up at the pan it's like on top of the pan plugging into something and the only part we could see of it were the 3 exposed wires. There was also another plug that looks like it should have been plugged into something but it was just loose. Any ideas what those would be?

[4.3LXJ]

Post some pics. You will have to get into it anyway. Tony will know. I haven't been an AW4, just fords and chevys.

[oderdene]

is reverse light lit on R position? I guess:
3 wire - solenoid control
2 wire - reverse switch

you can read the AW4 manual from http://www.scribd.com/doc/97292423/Aisin-Warner-AW4-Automatic-Transmission

[XJ Wheeler]

Are we sure its an AW4? I believe the 42re was an offering in that year as well, could be wrong though.

[gajeepguy]

Pics would be really helpful here... but I'd say that if there is a plug just hanging loose off your trans it should probably be plugged into something.



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[jdougn]

Yeah, get the wires plugged back in then test again. It sounds like the tranny is running in a high gear which is why it doesn't want to accelerate off the line but will run at highway speeds. One possible culprit is the Throttle Position Sensor. When it goes out the transmission has no way of knowing when to shift. Let us know what the symptoms are when the wires are plugged in.

[BlueXJ]

Clean the connections well before plugging it back in and tell us if your problems disappear.

[gajeepguy]

Yeah, get the wires plugged back in then test again. It sounds like the tranny is running in a high gear which is why it doesn't want to accelerate off the line but will run at highway speeds. One possible culprit is the Throttle Position Sensor. When it goes out the transmission has no way of knowing when to shift. Let us know what the symptoms are when the wires are plugged in.

Unsure if it differs but when my tps went the trans was stuck in 1st gear

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[gajeepguy]

Sorry, double posted somehow



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[mwheeler84]

Thanks for all the replies. I have not done any further investigation really but I think I may have narrowed some things down. To clarify I don't have the AW4 I have the 42RE.

The unplugged cable/plug I think is for 4WD which I don't have. This is what my father in law said it probably is which makes sense. The 3 wires that are exposed I believe is for the RSS, which yes I do have reverse lights so I know that plug/sensor is working. I would think that if that was shorting something out it would definately be shorting itself out which it is not.

I'm almost positive it's something with the TCM. I have determined that I am in "limp-mode". I can manually shift from 2nd to 3rd and the only time I can get 1st to work is if I am in neutral at a stop and drop it into 1st gear manually. Then I can shift through all 3 gears.

I have not had a chance to get it up to high revs, +4000 RPM, so I'm not sure if it will ever shift on it's own. It never goes into O/D and the O/D off switch doesn't ever turn on. It's constantly dark except when starting the jeep or when checking the tranny codes so I know the switch itself works/lights up.

Also, not sure if it's related or not but the ABS light is always on and my gas gauge works when it wants. It seems to be working pretty good right now (the lady I bought it from is the one who said it wasn't reliable). My gas light comes on when it's low.

The reason I think it may be the TCM is that the tranny codes it's throwing are 23, 22, and 21 which are all solenoids that are controlled by the TCM. Seems pretty logical to me that it wouldn't be all 3 solenoids but the mechanism that controls them which is why I was asking if there was a fuse that controls them. I have looked at the fuses under the hood that controls the TCM (#12 and #7 I think) and those are still good and not popped. One of them was hard to get out (on a freezing day in the dark with just my fingers) but once I got it out it wasn't popped.

I haven't checked the TV cable yet but will be doing that tomorrow afternoon when the sun is out and a little warmer hopefully!

Thanks all for the help. Any further suggestions are greatly appreciated.

[jdougn]

Make sure the TCM is actually plugged in. Your last post matches the exact symptoms that the AW4 in my XJ has if the TCM is unplugged. One way to see if the Throttle Position Sensor is at fault is to hold the accelerator to the floor and see if the TCM shifts the tranny at high rpms. This is how the local transmission specialist diagnosed the TPS in my XJ. (But make sure the TCM is plugged in first.) It was a new TPS but not from the dealer. As soon as a TPS from the dealer was installed the tranny started working perfectly.

[mwheeler84]

Make sure the TCM is actually plugged in. Your last post matches the exact symptoms that the AW4 in my XJ has if the TCM is unplugged. One way to see if the Throttle Position Sensor is at fault is to hold the accelerator to the floor and see if the TCM shifts the tranny at high rpms. This is how the local transmission specialist diagnosed the TPS in my XJ. (But make sure the TCM is plugged in first.) It was a new TPS but not from the dealer. As soon as a TPS from the dealer was installed the tranny started working perfectly.



No the tranny never shifts on it's own. The only time I can get it to shift is if I do it manually. Never upshift or downshift.