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Old 07-14-2010, 11:51 PM   #1
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03 makes a clunk only when slowing down

Greetings All,

Just today this has started, but has been consistent all day. When I apply the brake, the Jeep will "clunk" when the speedo hits 30mph. It is not a audible type of clunk, more of a physical can-be-felt-by-every-passenger in the Jeep type of clunk. And it ONLY happens when braking, specifically at 30mph.

I've tried to replicate it when accelerating, gassing hard up to 30 to see if it will do it, but it does not. I've also tried NOT braking, just coasting down from 40 to 30 or less, and it does not do it then either. It only happens when braking, and exactly at 30mph.

I've searched thru several threads, but I'm not certain that I'm phrasing it properly to find relevant threads.

The Jeep is an 03 Sport, 4.0L I6, 76K miles, and Auto transmission. Any point in the right direction, or suggestions on what else I should check for along with the "clunk", would be greatly appreciated!!

Thank You All,


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Old 07-15-2010, 08:50 AM   #2
that's what she said

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it could be the driveshaft u joints. that is a common thing to go bad and it it a cheap easy fix. grab the front and rear driveshafts and try to move them. if there is any play in them, that is probably the culprit of the thunk. i had mine go and it was only noticeable at low speeds <30 mph.

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Old 07-19-2010, 06:06 PM   #3
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Turns out, it is the transmission. Apparently, the hard downshifting from 4th to 3rd has a service bulletin to address it. The software needed to be flashed to an updated version to resolve it.

Of course, now the mechanic is telling me that the DBRIII can't even connect to the TCM/won't read, and most likely I will need to replace the TCM to fix the issue. I don't imagine that anyone knows if a place like autozone or advanced auto would be able to test the TCM to determine if this is correct? I'd really like to know that it is a simple fix and not a ploy for them to get more money/make a big repair out of a small problem.

Anyone have addition insight to this by chance?


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Old 07-19-2010, 07:03 PM   #4
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I had the ECM flashed on my 05 sport 2 days ago, It had a hard time takeing the instal for some reason. The tech had to end up trying it 3 times before it actually ended up working. Granted it was the ECM not the TCM it might have the same problem.
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Old 07-19-2010, 11:59 PM   #5
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Did you have any connection issues, or just with the flash itself?? I've been told that the Scan Tool, DRB device isn't even able to obtain information from the TCM at all. Did your tech experience the same problem?

I will inquire about this further with my mechanic and see what the results were to compare.


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