I just picked up my 02 WS6 last month. I have since put on a lid, headers, ory and a catback. When my tuner uploaded the file, he came up with these codes:

[Restraints] U1000 - Class 2 Communication Malfunction (History) (Immature)
[Restraints] U1016 - Loss of Class 2 Communication with VCM (History) (Immature)
[HUD] U1000 - Class 2 Communication Malfunction (History) (Immature)

What I know about the car's history is.....the owner said he had the PCM replaced because he kept getting some kind of MAF code that wouldnt go away. Apparently he tried replacing the MAF first with no luck. He also had some kind of handheld tuning program he used (not sure which one). Anyway, when I bought it, I told him to flash the tune back to stock because I have my own tuner who used HP Tuners. Knowing this, can anyone tell me why these codes may be coming up? I did a search but found so many different answers that I dont know what to think. The car drives perfectly fine and it wasnt setting an SES light, so Im a little confused. Can someone help me out?

 

These codes are set when you read/write to the PCM and disturb the comms to and from the VCM. It's just reporting the com loss between them that takes place during a flash. They will fall away over time and come back when you make changes. They do not indicate an issue for you or cause or reflect any harm.

 

Thanks a lot buddy. My tuner has tuned several of my LS1 cars and we have never seen those codes. Why would it be showing on this one and not the others if its just a flash issue?

 

Maybe he isn't paying attention; if he's he's reading and writing to PCMs, the codes are there.

 

Just sounds like the software is not properly erasing the DTCs of the modules after a write of the calibration. It isnt "Normal" to have them sitting as a pending or history code after a flash. You should be able to clear out the codes at any time. If they keep coming back, then usually it is a broken wire at a splice pack under the dash, Green with white tracer.

 

I don't know what HPTuners is doing after a flash; I guess it isn't wiping codes, but it damn-sure IS normal.

 

Well HP Tuners was able to clear the other codes that showed up, for example the code that set my ses light for having no cats. He tried to clear these codes but they came right back instantly, almost as if they didnt clear at all. Why wouldnt HP Tuners be able to clear these?

 

I always pay attention, I've tuned many different cars including three for Raise, and I have never seen these codes before on any F-body. They were there before we flashed it, after we flashed it, and they returned immediately after clearing all DTCs.

I have no history about the handheld tuner that was used, maybe it left some "dirt" behind?

 

I see them all the time FWIW. Never had a problem with them or the performance of the car.

Brent

 

I don't know what to say... I posted about them a little over 3 years ago when I first got the HPT software. Basically I was told that some "lesser" equipment was trying to talk to the PCM and was being interrupted and they are the source of the codes. It fits, it makes sense, when I first scan cars I don't see the codes, after I upload and reflash they are present. Their history perhaps remains in the module that sets them (the VCM or otherwise) which is why they immediately return.

I'm not trying to be belligerent or a dick, so I will bow out in case someone else wants to post, but that's my experience and it what I was told about them.

 

My 2001 has a VCM out of a different car and it gets these codes. They go away after 40 run cycles. I read that somewhere, they eventually went away.
They seem to come back when doing a calibration only.

My 2002 has the original VCM, it doesn't show those codes with a calibration only, it did show them when I did a write entire.

 

No need to bow out Steve. Noone is disagreeing with you. They are just stating facts about their own experiences. What you are saying sounds very realistic. As you see, my buddy Chad (LS1Sounds) chimed in and asked about leaving "dirt" behind. Since the previous owner used some sort of handheld programmer (now that I think about it I think he said it was a Predator), it sounds very likely that these codes are there from back then. Sound likely?

 

Find a shop with a tech 2 and I believe in special functions it will have a list of all the modules and if they are communicating or not, whichever module is not communicating unplug it and plug it back in and that usually fixes it. If not it usually is that module that is bad. Thats a really wierd intermittent code on a lot of gms. There is numerous bulletins out on all gm cars for u1000's.

 

http://www.hptuners.com/forum/showthread.php?t=10575
http://www.hptuners.com/forum/showthread.php?t=6766
http://www.hptuners.com/forum/showthread.php?t=9464
http://www.hptuners.com/forum/showthread.php?t=12148
http://www.hptuners.com/forum/showthread.php?t=7723

 

Well, it seems that this is a common occurence. It also doesnt seem to be a cause of worry. Im just curious why it didnt show up on any of my other cars that we tuned with HP Tuners. Hey Chad, take a look at those links that Steve (Frost) posted. It seems to be an update issue. Call me later and let me know what you think. Thanks again Steve.

 

They show up on both of my cars FWIW. I've never had an issue with them present.

 

Thanks guys. Frost, I will check out your links. Jamie, perhaps these codes were left behind by the handheld and will clear after 40 cycles.

I certainly saw nothing else amiss in the tune, logs, or driveability of the car. I wouldn't worry about it.

 

Cool...thanks Chad

 

Fwiw, I also get these codes and have posted to ask about them.

After my first read I got the two 'Restraint' ones and a 'Brake' one. Now after a second read I also get the HUD one. But, I get a 'real' P0420 code too.

[PCM] P0420 - Catalyst System Low Efficiency (Old) (History) (Immature)
[Brake] U1000 - Class 2 Communication Malfunction (History)
[Restraints] U1000 - Class 2 Communication Malfunction (History) (Immature)
[Restraints] U1016 - Loss of Class 2 Communication with VCM (History) (Immature)
[HUD] U1000 - Class 2 Communication Malfunction (History) (Immature)

 

dont worry they are normal we all see them.