Is this a serious code, U1255

[99Classillac]

I checked the code out and this is what it is. U1255 - Class 2 Communication Malfunction (Serial Data Line Malfunction).

Is that serious? Is my car's electrical system about to sh!t itself? Also got a code saying my traction control is stuck on off. How do I fix that? What's wrong with it?

[Ranger]

Not sure about the 1255 code. Have you pulled battery power lately? Clear it and see if it returns.

What was the T/C off code?

[Tonkin]

See this thread. might help
http://www.cadillacforums.com/forums...1255-code.html (IPC U1255 code?)

[99Classillac]

haven't unplugged the battery in over a year when I replaced it. the code for the TCC was P0741 - TCC System Stuck Off.
I also got a code P0440 EVAP system. I don't know whats going on. I also got a code P1599 - Engine Stall or Near Stall Detected. The engine never tried to quit on me but I know the computer can detect what I can't.

[99Classillac]

Hey Tonkin, thanx for the link. I checked it out. I feel a little worried. Does that mean something is broke and I gotta replace it? I'm gonna reset my codes and see if it comes up again. I hope not, that will suck. Is there a module for the trans? I'm thinking it might be the trans because sometimes it shifts funny and this hissing sound might be related. I wanna cry. My car is dyin on me.....

[Ranger]

Do a search for P0741 or TCC. Not a big deal, but expensive to fix. You can live with it.

P0440 means that there may be a vacuum leak in the EVAP system or there is a problem with the solenoid or control valve. It is emissions related.

[99Classillac]

Can a loose gas cap set off a P0440 Evap code?

[99Classillac]

I did a search on that P0741 code. Man does that suck. So does that mean my torque converter is slipping? Maybe that's why my mileage has been really horrible in the recent weeks. Maybe that's the hiss? But the car feels fast and doesn't feel like it's slipping while I drive. The only slippage I get is when it's really cold outside and I first start the car and put it straight into drive. It slips then but after a couple seconds, it is fine. Maybe that is setting the code? I guess I'll haul this car over to a stealership so they can fix my baby.

[Ranger]

Yes, I think a loose or bad gas cap can set the P0440, though not positive.

Yes, TCC stuck off means that there is a little slippage in the torque converter as opposed to being locked up at 41 MPH, but that should cost you no more than about 1 MPG. TCC does not engage at idle (if it did or was stuck on, it would stall the engine), so I doubt that is your cold starting problem. Have you checked the fluid level or changed it?

[99Classillac]

Hey ranger, I think I figured it out. I cleared the codes yesterday and they haven't came back. I did the search last night like u said and I found out how to do a simple check to see if the Torque converter was engaging. Go above 41 when the converter is supposed to engage. Then while holding a steady speed, tap the brake just enough to turn on the brake light. Doing that is supposed to disengage the converter. If it disengages, the rpms should go up and u feel a little bump. I did that and sure enough the rpms when up and as soon as I let off the brake pedal, the rpms went back down. I didn't push the brake pedal down hard, just enough to hear that click and the brake light comes on. So doing that tells me that the converter is engaging. Here's my theory on why I got that code. I have 20inch rims on my car. I drive to work thru the city everyday and I like to put my foot in the pedal a lot. Those rims aren't light at all. It takes more to move them than the stock wheels. I'm thinking all this stop and go and my foot going down on the pedal a lot was making the converter slip because it was hard to turn those 20's especially at WOT. I'm thinking when I was doing the WOT all over the place, it was making the converter slip because of the strain. What do you think? And the EVAP code, I had a check engine light on because I forgot to close my gas cap. I even got a message saying it on my DIC. That was last week. I could've gotten the code for that. My only mystery is this U1255 - Class 2 Communication Malfunction and P1599 - Engine Stall or Near Stall Detected. I don't know why I got those codes. But as far as taking my car to the stealership for the trans rebuild, na, i changed my mind.


PS I had my trans fluid changed about 10,000 miles ago. No flush, just drain, clean the filter, fill.

[Ranger]

Yup, loose gas cap will do it every time.

Not sure what to say about your wheel theory. There is always slippage in the converter. It's designed that way (til it locks up at 41 MPH).

[Tonkin]

Hmmmmmm. Responding to this thread can be hazardous to your cars health. After my post I drove over to the store and the SES light comes on and I now have a P0741 on my 2002 DHS! That's the bad news. Good news is warranty good till 11/21/08.

[99Classillac]

Yea I know there's always slippage, but I figured the 20inch rims was adding strain to the trans and creating the excess slippage that the sensor would pick up and throw that code.

LOL sorry about your car Tonkin. At least you got the warranty so you can get it fixed.

[CandyRedDHS]

i like that "stealership" funny yet so true...

[Ranger]

Originally Posted by Tonkin

Hmmmmmm. Responding to this thread can be hazardous to your cars health. After my post I drove over to the store and the SES light comes on and I now have a P0741 on my 2002 DHS! That's the bad news. Good news is warranty good till 11/21/08.

OH, OH Sure hope this isn't contagious.