U0402 help!

[AlleyCat]

So I am getting two codes. One if I do a burnout a little too long and a P something pops up. But the big one is the tcm code. It is shutting everything down to limp mode at about 125 mph. U0402. Diablo states it is probably a bad converter. But I had this code pop up a couple of years ago and it magically fixed it self. I just had a new transmission installed. So the dealer is going to take her back and run some diagnostics on the tcm. Does this have anything to do with the tune or is it a bad tcm/valve body or bad converter?

 

[Tape]

I would check for a
Faulty Transmission Control Module 1st or lose connection

 

[Paladin06]

Following

 

[AlleyCat]

Well if you go to you tube tv and do a search “Tucson Wednesday night drags” you will see me run 12 minutes into the video. I lifted the front wheels momentarily and backed off and got back on it again and then at 1100 feet it went into limp mode and finished at only 125 mph at 9.8. Normally I can go 144 at a da of 5000 feet. My friend and service advisor at Chrysler thinks it is the valve body. It goes in Tuesday. But I also noticed on the passenger rear I dug into the metal with the slick. That also could set it off due to different wheel speeds and the Ecu trying to protect the transmission and me. I took the sledge today and took care of that.

 

[FFBOS]

There is a harness that runs behind the liner in the rear on the passenger side. Was that hit?

 

[AlleyCat]

Ahhh. Thanks. I will check.

 

[sublime392]

Did you ever figure out this issue? i have the same code and my car wont do a burnout

 

[Hunter]

Did you ever figure out this issue? i have the same code and my car wont do a burnout

Welcome to the site.
Lots of very knowledgeable people here.
Love to see some pictures of your car.
Hope you post in the "New Members" forum.

 

[Diboblo]

A "U" code is a comms error, not a hardware error. Most likely, there is:

1. A damaged wire, or wires, in the TCM harness, or

2. Bad, or loose connectors in the TCM circuit.

I would disconnect at the TCM and reconnect, making sure all connectors are seated properly. Also, disconnect at the transmission and make sure all are seated properly.

Check for bent pins, that might not be indexing properly, with the mating connectors.

Lastly, if this doesn't help, check end to end for continuity between trans and tcm.

Eshift and canbus pins are the 4 you want to focus on.

Could also be a problem at the STAR connector junction. Trans is on the "C" bus. If you have messed around the STAR connector area, maybe a connection was knocked loose and is now intermittent. Wouldn't hurt to seat those connectors, also.

 

[BULL]

A "U" code is a comms error, not a hardware error. Most likely, there is:

1. A damaged wire, or wires, in the TCM harness, or

2. Bad, or loose connectors in the TCM circuit.

I would disconnect at the TCM and reconnect, making sure all connectors are seated properly. Also, disconnect at the transmission and make sure all are seated properly.

Check for bent pins, that might not be indexing properly, with the mating connectors.

Lastly, if this doesn't help, check end to end for continuity between trans and tcm.

Eshift and canbus pins are the 4 you want to focus on.

Could also be a problem at the STAR connector junction. Trans is on the "C" bus. If you have messed around the STAR connector area, maybe a connection was knocked loose and is now intermittent. Wouldn't hurt to seat those connectors, also.

More points in your column. ; )