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Jeep Grand Cherokee, SUV
#875 of 1068 O/D kicks off on highway
Nov 01, 2011 (5:08 am)
Does anyone have a solution to an Overdrive lock out while on the highway? I have a 2002 grand cherokee with 2wd. It has 140,000 miles on it. operates fine normally but after about 30 minutes on the highway around 70 mph it drops out of O/D into 4th gear. The O/D off light comes on but not the transmission temp light. I do not believe this is because of a high temp. Although it does not do this when the jeep has cooled down. If I shut down for 30 minutes it goes away until the temp comes back.The fluid level is normal and condition of fluid is good. Not sure where to check first. Any help would be appreciated, thanks-Mark
#876 of 1068 Re: O/D kicks off on highway [madmariner72]
Nov 01, 2011 (10:01 am)
Hi,Sounds like we have similar problems. My 2001 Grand Cherokee drops out of top gear/overdrive down into 3rd gear when the engine reaches running temp. The diagnostics equipment has said it is the throttle positioning sensor and a new one has been ordered and should be fitted tomorrow! If it answers the problem I will get back to you right away!
#877 of 1068 1999 Grand Cherokee Tranny surges
Nov 04, 2011 (8:41 am)
hey, I have a 1999 Grand Cherokee 4.7, and I recently had someone replace the radiator, and since then whenever I first start the car and drive, hot or cold, it seems to have a high rev when first going, and then it subsides after a bout a quarter mile, it revs up to 2k rpm and then acts normal, through the rest of the trip,even at stoplights. I told my friend about it who replaced the radiator, and he said it may be not enough coolant or that there may be air in the cooling system, but I check all that, and he also said to make sure that the tranny fluid is high enough as some came out but not a lot, and it seems fine too, but there were bubbles in the tranny fluid so i added a little more, bout a half quart as i am not sure why it would only do this when I first start the car and drive. It has never done anything like this before, so could it be not enough tranny fluid, air in the tranny, or????
#878 of 1068 Re: 1999 Grand Cherokee Tranny surges [malbeck]
Nov 04, 2011 (11:36 am)
There is some issue with the transmission cooling lines and/or the cooler portion of the radiator.
I have a 97 Jeep. The transmission was acting funny. It was surging a lot. Next, the water pump went. So I decided to replace the pump so I could drive it to transmission shop so I could at least get a rebuild quote.
I noticed the transmission cooler lines were leaking. So, I decided to replace them while I was under there.
Guess what? The transmission problems went away!. My theory is that any issues with transmission cooler lines somehow affects the pressures inside the transmission.
If you really like the car, here is what I would do.
1. Disconnect fluid lines at cooler.
2. Get fluid out of the cooler
3. Find out what pressure the trans cooler should be tested at and test it
4. If pressure test not OK, talk to a transmission shop before you go back to the mechanic or where you bought the new radiator.
5. If pressure test OK, replace both transmission cooler lines and test drive.
NOTE: The trans cooler lines should be bone dry
You may need a special tool to disconnect trans lines at the cooler.
After working on it follow procedure for adding fluid. If the fluid level is low it will act funny.
#879 of 1068 Re: 1999 Grand Cherokee Tranny surges [rwengr]
Nov 07, 2011 (1:01 pm)
I will check the lines and see if there was any damage done to them. I keep hearing about it may take a special tool to remove the tranny cooler lines when doing a new radiator install, but when this "guy" took them off he just used a wrench, could he have damaged the lines by taking them off and putting them back on wrong? The tranny fluid is fine, and so is the coolant levels, it just revvs along at 2k rpm's until you get about a 1/4 mile then kicks in. Seems that there is a pressure issue somehow that was not there before the swap out. Could the radiator cause this? It's a new aftermarket, and I have had no overheating issues either, just once when we were putting in coolant, but the car was not driven it just overheated initially as the coolant was not circulating properly after we put it in the radiator, and then we put the coolant in the bleed hole and it was fine. Could something have gotten wet from the steam/coolant coming out when we had to bleed and put coolant in? I am sorry for all the questions, but I am stumped as to what is causing this to happen, and only when I start the car hot or colds.
#880 of 1068 Re: O/D kicks off on highway [madmariner72]
Nov 11, 2011 (6:00 am)
Finally I got a good result! As my first message stated the 2001 grand cherokee would drop out of top gear/overdrive once it reached running temp. Many checks were done and to no avail. Sticking solenoids in the tranny was suggested and perhaps may be the case in other vehicles however turns out that in my case it was diagnosed as the output speed sensor, a $40 part. A new one was ordered however on fitting it it was found that it was the connector to the output speed sensor that was at fault and a recrimp sorted that out! six weeks of hassle and thoughts that a new tranny may be needed and it turned out a basic connection! I hope your problem is as simple to fix and it sounds identical to mine.
#881 of 1068 Re: 2001 jeep tranny problem [2001jeep1]
Nov 11, 2011 (3:10 pm)
This is what the problem is that the trans shop or stealership wont tell ya.
Nobody on these forums can figure it out because i had the very same problem and all they can say is rebuild. Bullcrap!
What it is,is a pluged trans line and or radiator. On one of the lines between the radiator and the trans lines is a check valve that gets plugged. Which causes the radiator to also plug. It is a very easy fix with a air compressor. I changed every sensor and silinoids and still the same problem. The OD light would come on and about a couple of miles later the trans overtemp light would com on. The reason is the fluid isnt flowing through the radiator and it takes a while to overheat the trans.
So undo the trans lines at the radiator and on the trans a
nd aslo take that check valve off the line and see if that little ball bearing is stuck. blow air through the lines and through the radiator and also the check valve and you will find why your trans is throwing codes and overheating!!
I spent alot of meaningless money to find this out. Hope this helps dont rebuild
#882 of 1068 Re: O/D kicks off on highway [culbo]
Nov 11, 2011 (3:14 pm)
I bet you burn out anther speed sensor because mine was doing that also.
That sensor is burning out because the trans is getting to hot.
#883 of 1068 Re: 1999 Grand Cherokee Tranny surges [malbeck]
Nov 11, 2011 (3:33 pm)
This is because when he replace the radiator he bypassed or took out the little check valve thats in the one of the two lines that goes to the the radiator, Im willing to bet because thats what that valve is for. Or its a bad check valve. Transmission shops will take that little valve out when they rebuild and upgrade your shift kit
It is right up front and easy to get at . And causes alot of trouble as you can see on this forum. Mark
#884 of 1068 2012 transmission
Nov 14, 2011 (8:14 am)
does anyone know if the new 8 speed transmission will be used for JGC and if so when? TIA