I got an 09 with 37000km when going slow and hitting the brakes truck makes a loud clunk and lerches forward 10 to 15 feet.Tranny also shudders when shiffting gears and shifts very hard sometimes at all speeds.Running 285/70/17.Dealership cannot duplicate and no codes have come up.Anyone have any Ideas be for I blow the thing up.

I too have experienced the exact same problems. I have a 09 3500 dually, with 58000 miles , and is currently at the dealer for repairs . But when my truck did this at a stop, and I took back off, the engine light came on and it would not upshift into any higher gear. There happened to be a dealer close by that I eased over to it. They looked at it and cleared some codes, we test drove it and it happened again, so road side assistance sent a tow truck to tow it to a dealer that worked on the allison trans. So far it points to an elictrical issue , as I was told by the dealer its at now, and also it has 48 different codes and they are searching for the source of the problem. My advice would be if it happens again, keep taking it back ,before u get stranded in limp mode and 3 hours from home like I did, because there should be some kinda codes. Also they did say that the allison will pressure up the line pressure to keep from a major problem occuring and that is why it jumped around and lunged forward so harshley, because of some internal , electrical or mechanical problem. Oh and one more note, My truck is completely bone stock as it came from the factory, so no mods have caused this either.

Hey Thanks for the info.mine has done this three times in the last month,but no engine light or codes.Did you notice any bad shifting before this happend to you.I get lot of shuddering with shifts when I pull a trailer or when Iam on it hard.With very light pedal pressure I get the hard shifting that jolts the truck a little.My truck is stock except for a leaveling kit and 285/70/17.

Hey Thanks for the info.mine has done this three times in the last month,but no engine light or codes.


Have you actually checked engine and trans for codes right after it happened even though you had no light?

Anything non stock on it?

Truck is stock except leveling kit and bigger tires.No I didn't have it check for code right after.Work is really busy and had no time.How long do codes last for in the memory

Truck is stock except leveling kit and bigger tires.No I didn't have it check for code right after.Work is really busy and had no time.How long do codes last for in the memory


40 drive cycles.

As far as my trans shifting hard or erraticlly it never did anything other than normal operation. Now the clunk before stoppping , it had done that earlier that day , but not as bad , and it didnt get hung in limp mode. My original plan was to get it back to my home dealer , which it did end up at , as a result of a tow truck. For an update , my truck was at the dealer for a week total, and there indications from all the codes pointed to a faulty TCM. They ordered a new one , installed it and I got the truck back, and all seems normal and smooth as it had always shifted, with no clunk stopping or taking off.