99 Jeep Grand Cherokee-overdrive issue

J

Jamie

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#1
Guys I need some advice. I have had this 1999 Jeep Grand Cherokee a few years now and well its issues have issues. My main concern is the transmission not working in overdrive. I live in Georgia so it doesnt get cold here often but last winter when it did drop close to freezing I noticed it workign in overdrive for about 10 min or so before dropping out of 4th gear and back to no O/D again. This didnt seem to matter if I jumped in and took off or let the engine warm up for half hour first so engine temp doesnt seem to matter on that. The button on the shifter never has seemed to work at all but not supprising since I also have yet to see an engine light either. I have the correct fluid in it and correct levels in the transmission.

I checked the codes and found these ... P0132 , P0171 , P0711 , P0720

As I said its issues have issues so I will list all the other stuff it has going on. I doubt any of it could be related but just in case they are maybe it will help.

Other issues/symptoms :
-bad hub front right, bad rotars and needs pads ( fixing that in a few weeks )
-no cruise control
-no A/C, compressor dont come on and fuses are good
-runs out of gas just over half a tank every time
-Problems with idle intermittently only right after startup. Once going it clears up until shut off again.
-Rarely I get electrical problems with speedometer, radio, heater control, and some lights all go out and then come back... very rarely
 
J

Jamie

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#2
Sorry I also forgot to mention its the 4.0 in line 6 engine in that. And I have looked for my TCM on the advice of someone at work, I dont seem to have one of those in my Jeep so still lost on this... maybe PCM, not sure... help.
 

nickb2

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#3
Hi guest, WOW!! Those are alot of symptoms. I will need time to check each one out.

P0171, fuel system lean. The exhaust manifold leaks, a crack is visible to naked eye. All 4.0l have this issue.

P0132, O2 sensor shorted to voltage. Check this out and replace also if you have to replace the manifold.

P0711, trans temp sensor, no rise after start. If memory serves right, it is under the battery.

P0720, low output speed sensor rpm, above 15mph. This probably your problem with over drive.

If you really like this jeep, gonna need some time to get her done. Do have emission testing where you live? Do you know to pin test wiring with a DVM/voltmeter. I am suspecting two issues here. A corroded connector/bad ground/short that supplies voltage to these circuits and a cracked exhaust manifold. I will supply a power distribution circuit diagram, study it and test.

Also all the other issues such as brakes/ hubs/ etc, Is this truck worth it to you. This is only a question. Cuz if you cannot resolve all these issues by yourself, parts, labor and diagnostic will be the price of this jeep. So if you are really attached to it, go ahead, but think it over if you don't have skills. That was my $.02

However, I am looking more forward to removing power distribution center and inspecting each every wire/connector/ground/relay etc. Hope my advice proves good, cuz I have seen hundreds of these fail due to corrosion there. :idea: :eek: 8)
 

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billr

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#4
Yeah, with all those other problems there should be no expectation of normal trans shifting.
 
J

Jamie

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#5
that's not even the full list of problems... as I said its issues have issues. lol.

Most of these problems such as hub, brakes, no left turn signal, and even the fuel pump can all be fixed for under a hundred if I do them and yes I can. However I want to make sure I don't have a major problem with my transmission because as you hinted too, is it worth is. If I have to get a hole new trans or rebuild it, i.e. get someone else too, it could get real expensive and hense not worth fixing the other stuff. but if I can resolve that and live with the minor stuff then great.

I plan on giving it to my son as his first car in less than a year, in the mean time its just a work car and well it gets me to and from so I will drive it until the wheels fall off so to speak.

No we do not have emitions testing here so that's not really an issue or option. Yes I can test the wiring, I am an aircraft avionics tech for the airforce so I do have some skills. Just need a place to start and some sort of hope it can be done without getting into the not worth it zone. basically I am prioritizing whats most important and working my way back... he will be a 16 year old boy so its expected to have some things to work on with his first truck and I will have him help me fix a lot of these as a life lesson.
 

billr

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#6
Even a trans overhaul can be a fairly economical DIY job if you have the time and patience.
 

kev2

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#7
OK USAF avionics my day that was B shop and they were fairly handy with a DVOM and a wiring diagram

Jeep - fairly easy to work, have owned 4, lets get at it - Where do you want to start-

post the code, issue , you want to tackle first-
 
J

Jamie

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#8
great, and your right I was a B shop guy and A shop aswell, now comm nav and work with diagrams daily.

As for the O2 and exhaust lets face it that can be more of a nusance than anything and we can fix that later down the list. For now the jeep runs good and I want to insure it runs better and safer for him in the future so we need to tackle this transmission problem and anything else wrong with it.

I noticed today a new symptom with is, not sure if its hole related or not but may be a sign of a bigger issue. It was really really hot today, 108 heat index. I had to drive a lot with my four boys starting football today and on the way home after a lot of driving the jeep dropped out of gear... RPMs up as if I had a stick shift and pressed the clutch in. I feathered the gas real easy and it caught a few times and started going again... few more miles it did it again and I nearly had to pull over before it caught again. Later in the evening after time to cool down I went to town a few miles up the road and it seems ok but that kinda scared me some.

The only other issue that would be real pressing I should take care of would be the idle issue. It only does it on start up. it idles real sparatic kind of a surge. If in gear it will shake the car with each surge and even lunge me forward. Usually it does this right after starting the car, cold start or warm. I feather the gas and it clears up fairly soon and never does it again until I turn it off again. More of a nusance to me but for my kid will need fixing.

The other stuff on the list will have to wait until I have more time and more money to get the parts. Most are already easy jobs like brakes, rotars, and hubs... just need the parts is all and I will have him do most of that stuff.
 

billr

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#9
There are two points I am trying to make here:

1) If the exhaust leaks or such are causing fuel trims to be out of limits the PCM may intentionally inhibit some trans operations to reduce chance of damaging the engine. There is no assurance that the trans is misbehaving until the engine issues are resolved.

2) Remember this list?

"-no cruise control
-no A/C, compressor dont come on and fuses are good
-runs out of gas just over half a tank every time
-Problems with idle intermittently only right after startup. Once going it clears up until shut off again.
-Rarely I get electrical problems with speedometer, radio, heater control, and some lights all go out and then come back... very rarely"


They may all be unrelated, however all could be caused by electrical problems; most likely a grounding issue when so many seemingly-unrelated things happen. If there is a system-wide electrical problem, then trans shifting would also be affected, since this is likely to be an electronically-controlled trans. Track down those other problems, if they turn out to be electrical, then the fixes for them may take care of the trans.
 

nickb2

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#10
I am not promising(that was a disclaimer btw :ROFL) But I would really bet on PDC. Just take it off and apart and check for loose connections etc, and study the attachments i posted, these are essential to all your symptoms.

Do not go throwing a tranny rebuild etc without a thorough electrical check :idea: $.02

Because as Billr said, read your list of symptoms, you have multiple/severe issues involving different modules, and it is highly unlikly that they all gave at same time. As for mechanical issues, that is another story :thx 8)

No MUX line on board here, only BUS line and CAN obd2 protocol. So easy to scan and pin test. I like this thread, it has stimulated my neurons. ;D

That being said, saw the movie "jarhead2" today with buddies and beers, great action movie. Here is a link for all my pals here for the weekend 8), You guy's are great at giving advice and stuff. ;) Awesome movie on a big screen, I only have a huge old projection tv but it was insane.
http://www.ahashare.com/torrents-details.php?id=456303

Had to modify, reread my bad english 8) I don't want to brag ok? I worked at a Chrysler dealership up in quebec city back when those 99 jeeps came out, I fixed so many of these jeeps with same issues under warranty. Imagine. So plz look to pdc first before investing. Billr is on a wonderful/nightmare project with a old 67 bronco 289cc. We will help you the best we can!! When push comes to shove, PUSH. :thx

I am hoping your son will enjoy it, mine is 12. so don't have to worry yet. ;D
 
J

jamie

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#11
thanks guys. and your right, a lot going on and most where all there before I bought it... I know I know but leason learned right, I got it cheap.

However, the exhaust and O2 related codes are relatively new, within a few months. a year ago when I was looking into this it was just the 01## codes for transmission and that's it along with the symptoms. This is why I put all that because as on aircraft things can and usually are related in some way even if in a strange round about way.

as you said the mechanical things like brakes and rotors will wait because well its point blank what that is and there not hindering me until I do give it over to him... and its something he can fix himself with my help so father son project.

I will check out the PCM this weekend as you said and look for any loose grounds or corrosion anywhere. I have seen that before and with the condition it was in when I got it not a bad idea, I did have to change a lot of fuses when I got it.
 

nickb2

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#12
I think you misunderstood my english. You NEED TO PIN TEST. PDC and between PCM etc. You say you have skills, so backprobe. Easier that way. But with patience, you can show your son how to pin test and use a ratchet and a paper clip :D

There are to many codes for this to be normal.!!! Here is a sloppy link to show you or others where these manifolds crack.
https://www.google.ca/search?q=jeep+4.0l+exhaust+manifold+crack&client=firefox-a&hs=6gB&rls=org.mozilla:en-US:eek:fficial&channel=fflb&tbm=isch&tbo=u&source=univ&sa=X&ei=LVLmU5bYM8GjyASYpoCACw&ved=0CC8QsAQ&biw=1064&bih=641#facrc=_&imgdii=_&imgrc=Lteg1beBKb0RPM%253A%3BmtJuqSK6HcXKBM%3Bhttp%253A%252F%252Fpics.livejournal.com%252Fmrflash818%252Fpic%252F00070421%252Fs320x240%3Bhttp%253A%252F%252Fmrflash818.livejournal.com%252F84017.html%3B320%3B240

Like I said, hundrends of these I have seen. They are cast iron and can be welded :idea: $.02
 

kev2

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#13
Check your PM - that is personal messages - OR "my messages" right above the red line above...

I would look at the trans issue first- thats the big ticket item
jeeps require the correct fluid- NOT universal not one type fits all -use ATF +4, ONLY

get some of that a filter, pan gasket, AND this will start the gang talking* a output speed sensor.
Change sensor - drive advise-

* I always bitch about swaping parts without checking BUT this is a cheap sensor
remove clean, new O ring, ohm reinstall OR just put the 15$ new one in.... check the connector wires R&R advise.
 

kev2

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#14
OK JAMIE - I see a problem - you are a guest- SO I cannot send you messages -

SUGGEST you register - nothing bad will happen - then we can Email and get you some diagrams tech materials that will NOT fit in the forums..
 
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#15
ok, fixed the loggin problem... ment to and forgot too.

I don't seem to have my meter anymore, house fire two months ago, long story... however I do still have some tools and at some of your advice I tried some things with what I have limited. I can always get my meter from work Monday and jump head deep in that once I figure out where to start.

what I did, I removed all the plugs on the PCM and basically every plug on the car I could find basically, I kinda went nuts. Other than a lot of corrosion on the battery everything looked pretty good. Found one chaffing wire and fixed that but didn't seem to do any good. I put it all back together and drove it to town, about 10 miles or so, and on the way back checked codes again... none. I also did the key thrick three times to check codes on the Odometer, none. Perhaps they will show up later on again but strange.

still didn't fix any of the problems though, still no O/D, cruise, A/C, or clue... but hey, still drives ok for now I guess and hasn't blown up in a ball of smoke so thanks for small victories huh... lol. Will dive into it again on Monday to see what I can find, and soon as I get paid next week I will try changing out the fluid as you said, can't say for certain exactly what they put in it so worth a shot.