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Jeep Grand Cherokee Transmission Problems

511 messages,  Last post on Dec 07, 2009 at 2:50 PM

You are in the Jeep Cherokee and Jeep Grand Cherokee Forum. Your Hosts are steve_ & tidester

What is this discussion about? Jeep Grand Cherokee, SUV


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#446 of 511
Re: Transmission Shifting Problems [nneal] by xelvis66x
Nov 06, 2009 (8:04 pm)
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Replying to: nneal (Nov 06, 2009 5:18 pm)

Sounds good to me. I had the scanner hooked up tonight with my brother watching it and everything is working and there's no codes, we cleared them so now I'm going to drive it tomarrow and see what happens. It tells me the readings of all the sensors to do with the tranny, so I want to see if they are correct. Also the scanner says that everything is good and ok to drive.
 
Do you think the TCM could have gone bad. I was reading about them and TCM tells the tranny when the best time to up shift and downshift, but there is only one shift solinod in that tranny which is for the OD and the rest I think is controled by shift valves. and the solinod is working because I have all gears.
 
I need to look at the engine again I ran out of time. I want to check wires to the TPS.
Thank You!
#447 of 511
Re: Transmission Shifting Problems [xelvis66x] by nneal
Nov 07, 2009 (4:17 am)
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Replying to: xelvis66x (Nov 06, 2009 8:04 pm)

From what you've discovered so far, I don't think the TCM is bad. I have a spare one which I used to switch with the factory one to rule out the TCM, and that has never gone bad on me. I've read some people have had the dealer reprogram (or Flash) them, but it's not cheap. Yes, from what I read your TCM controls the solenoid for 3-4 upshifts and back down. Shift valves control the 1-2 and 2-3 upshifts (and back down I assume - they don't say). But what actually controls the shift valves themselves is the TCM, because it controls what the governor pressure solenoid does - and that is how much pressure the shift valves have to work with. So actually, there are two solenoids, one is a shift solenoid (3-4) and the other is a governor pressure solenoid (valve body), from which controls your shifting. The clinker in all this is that your TCM relies heavily on inputs from all your sensors, so they make a good weak point.
 
  One thing I thought of and read somewhere, is make sure the ground strap from the engine (or tranny) to the frame is good, otherwise it will mess up all the electrical parts and make them act strangely. Especially after working with the head, there might have been one connected to it.
 
  You're lucky you've got the tools and a brother who knows what he's doing. Best thing is, don't get discouraged because in the end I'm sure you're going to find it's only a wire or small component that's screwing things up. I've been there many times.
#448 of 511
Re: Transmission Shifting Problems [nneal] by tuggajb
Nov 07, 2009 (10:41 am)
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Replying to: nneal (Nov 07, 2009 4:17 am)

there is a ground strap from the back end of the head that you could have forgot to hook up
#449 of 511
Re: Transmission Shifting Problems [tuggajb] by xelvis66x
Nov 07, 2009 (5:46 pm)
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Replying to: tuggajb (Nov 07, 2009 10:41 am)

There's not one of them on mine but I know what you mean. When my brother work on his cherokee a few weeks ago (headgasket) we had to unhook that strap, but the only thing that is in the back of mine is a plug, I think with one wire and I checked I out and played with it and it didn't change anything. Do you know what that wire is for. It screws in to the head then a plug hooks on?
#450 of 511
Re: Transmission Shifting Problems [nneal] by xelvis66x
Nov 08, 2009 (4:38 am)
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Replying to: nneal (Nov 07, 2009 4:17 am)

There was no ground strap on the back of the head like my brothers, a one wir plug which I had to unhook. This screws down into the head then the plug hooks on from the harness. Could this be my ground to the head.
#451 of 511
Re: Transmission Shifting Problems [xelvis66x] by nneal
Nov 08, 2009 (7:38 am)
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Replying to: xelvis66x (Nov 08, 2009 4:38 am)

Could very well be. Either way, the transmission has to be grounded to the frame in some way for it to work right. A corroded ground would cause the same problems. My Jeep has a flat braided strap (wire) from the head to the firewall. I don't know what 95 models used.
#452 of 511
RE: Answers & Solutions by nneal
Nov 08, 2009 (8:12 am)
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I would like to add a request to all the people posting their vehicle problems in this forum. If you have found what was causing the problem in the message you posted, please let the rest of us know what your solution was so we can all benefit by it. I've learned and discovered many solutions in forums like this not found anywhere else. Many of them are not to be found anywhere, not even from the manufacturer. Forget garages and transmission specialists, as they are not going to throw away easy money. Feedback benefits everybody! Thank you.
#453 of 511
Re: Transmission Shifting Problems [nneal] by xelvis66x
Nov 08, 2009 (10:40 am)
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Replying to: nneal (Nov 08, 2009 7:38 am)

You think oil will make a ground short out because there is oil on some of the plugs and I've been spraying them with WD-40. I'll ave to look and see if there's a ground.
#454 of 511
Re: Transmission Shifting Problems [xelvis66x] by nneal
Nov 08, 2009 (11:19 am)
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Replying to: xelvis66x (Nov 08, 2009 10:40 am)

I doubt if oil would affect anything, although the cleaner the better. After having driven it some, are you still code free?
#455 of 511
Re: Transmission Shifting Problems [nneal] by xelvis66x
Nov 08, 2009 (2:14 pm)
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Replying to: nneal (Nov 08, 2009 11:19 am)

Yesterday I drove it to my buddies house and put the scanner on it and I had a code 13-VSS in the tranny and the code 24-TPS in the engine. And the night before we cleared the codes, but nothing has been showing up, also I took voltage reading on all the sensors from the scanner and they are around specs.

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