After running out of gas and being pushed to safety IN GEAR by the Highway Patrol, and then needing a jump-start from the battery dying while waiting for a tow truck, after a day or so, the "Service 4Wheel Steer" message came up on the DIC, and it defaulted to 2WS. Rebooted the system (unhooked the battery), and the DIC went away, function returned to 4WS, until the next day, DIC came up again. Any idea what could be damaged here? Ground connection(s), something fried, damage to something forom being pushed, computer issue, bad sensor, just a coincidence? Nothing looks physically damaged, and it DID function correctly for about 24 hours after resetting.

I'm so spoiled by 4WS, I can hardly drive this thing like this!!!!

Welcome to the site.

May not have cleared the memory of the code. As mentioned by others, For a memory clear, try this shortcut; touch the pos and neg cables
together once one is removed from the battery.

Hopefully thats all thats wrong.

Thanks, I will try that if it happens again. The condition seems to have cleared itself this time. I parked it at lunch, but now it's fine when I went to leave work.

It's back. I even cleared it with the trick above last night, and it came back a few feet down the road this morning. I need to get a code reader on it. Does it require a special type?

If you're paying for OnStar, give them a call.

Many auto part stores have code readers you can use for free, autozone does. You can retrieve and reset codes with them. You need a tech 2 to trouble shoot it though most likely.

srode... the scanner at AutoZone is not capable of retrieving trouble codes from the 4WS module. The steering computer is not part of the OBD-II mandate, and is manufacturer specific.

I've been down that road, and lived to tell about it.

A generic scan tool such as what is available for free, for rent, or even for purchase at an auto store is capable of reading an amazing number of engine and transmission codes, but not body or chassis codes. In fact, the scan tool at Autozone was not even capable of reading a driveline code with the Transfer Case.

With a "Service 4WD" message staring me in the face, the Autozone scanner showed no codes. Nada.

However, ONSTAR, on the other hand, is a great suggesstion by SS CREW. OnStar can not only find the code, if you ask nicely, they will even give you the PID code numbers they found.

Once I had the code from OnStar, I looked in the service manual, and then knew exactly what to ask the dealer.

Thanks for the Onstar suggestion, but if I had Onstar, I would have already done that. I am getting a friend's PC scan tool. Maybe that will read it. Thus far, it's been very intermittent. Basically it's every other day it comes on in the morning and stays on most of the day.

No one was taking anything for granted, guumbah, on the Onstar suggestion.

I had Onstar for over a year before I discovered that the Onstar diagnostics could do more than just tell me if the airbags deployed or when my oil needed changing.

Since I could easily determine mileage driven and oil change intervals without OnStar's help, I sort of wrote OnStar diagnostics off... until I was desperate to know why my Service 4WD light was on, and I had already exhausted all other solutions... including a PC based software scanner like you are about to try!

That's right. Not even AutoEnginuity (with Enhanced GM diagnostics), nor AutoTap, are capable of delivering certain fault codes of various body and chassis specific modules.

Those software based scan tools get the same OBDII, and now CAN, protocols as the hand held scanners, only the software programs have a more comprehensive human interface with simultaneous PID monitoring enabled by a larger screen.

This lesson almost cost me $500. It is not until one spends about $1,700 for a scan tool that one can pick up all the codes from the various body and chassis modules in our trucks. It might have to do with who pays GM for licensing the code, or whatever... the "why" to the question is just speculation on my part. I only learned the "what".. what works, and what doesn't.

Affordable (ie. $750.00 or less) PC scantool software provide LOTs of information about the engine and transmission, but, just like the affordable (Sub $1000.00) standalone scantools, the PC scanners fall short of diagnosing Quadrasteer and the transfercase.

On an intermittant "Service" message displayed in the DIC, if and when the message goes away every other day, it does not mean that the problem went away. The computers go through a variety of checksums during every drive cycle, and when the data doesn't add up, bing the light goes on and stays on until the drive cycle is restarted.

I had the false hope that my problem was gone after disconnecting the battery for 30 minutes, yada yada. The only reason why my Service message didn't come back right away is because I didn't drive it in such a way as to enable a condition for the data to not add up. Once I did, blip, up comes the Service message again.

Frustrated at seeing no faults from any affordable scan tool solution, and the light returning, I called ONSTAR only to get me to the nearest dealer. To my surprise, Onstar was able to give me the code. Here I had Onstar service all this time, but didn't realize they could do this.

I don't have much hope for your friends PC scan tool. I'm thinking you might have to go to a dealer with a Tech II, or an independent shop with a professional scan tool like a SnapON M2500 or higher.

good information, I knew the auto zone tools wouldn't pull transmission codes, most won't.... that's why I have a tech 2 Maybe you can find someone near you that has one that will get the information for you?

Thanks for the info! I will let you know if the PC tool works. Supposedly it can pull U and C codes, but maybe not ones from this system.

Someone on another board suggested it might be my battery is on the verge, and when starting the voltage drop is too much for the computers to talk properly over the Class 2 bus. Sound plausible? How much will a dealer charge me just to pull the code?

BTW, it's been off for two days now.

Some more symptoms:

Happens in gear or out.
Happens in 4WS or 2WS
Seems to only happen (when it does) the instant I turn the wheel to the left, whether centered or not, and not at all to the right. If I am centered, and leave the wheel alone, I can put in gear and drive off, and it won't kick on until I adjust left, even a hair. Backing out, it will not come on the whole time I move the wheel to the right, but will kick on as soon as I go to re-center, moving or not.

Does this seem like a bad sensor to you guys? Maybe something needs to be calibrated? I'm still leaning towards something getting off kilter from being pushed in gear. If not, it's quite a concidence that something failed on the Qsteer within 24 hours of that.

Still waiting on the PC hookup...

I would take the vehicle to a dealer and have them hook up a "Tech II" to the vehicle and they will be able to tell you what the problem is in a few minutes.

Running the vehicle out of fuel should have no effect on the system.

This is probably too late, I only read this tonight. But, as srode asked me to do, this info might help.

I had the same code on my 2005 1500HD QS and ended up taking it to the dealer. (costly) They found the problem with their scan tool and replaced the 4 wheel sensor. P/N 88962315 fixed it.