I have been having Service 4WD light coming on when I pull my 5th wheel a few times a day.
I just drove from Alaska to Oregon pulling my 5th wheel. There was a lot of rain along the way. Part of the time NO light was showing that it was in 2WD at one time it was showing it was in Neutral but was going down the road fine. I was Wondering if there are wires going to the transfer case that are exposed and could short out when wet.

Another Problem popped up the Service engine light came on for a couple of hundered miles then went out and has not come back on. The book says it has to do with emissions. so I wasn't too worried about it. I'll have it checked out now that I'm in the States again.

When in Cruise control and it shifts down the second time on a steep hill it starts blowing black smoke and loses power like my old 6.5 did when the trubo controler didn't work. do these have the same problem? Also when in cruise and it does that it won't shift after going over the top of the hill, it just stays at high rpm and the lower gear until I kick out the cruise control.
Any Ideas on this.
Once I got to where things were dry it all seamed to work better.

ANY thing I should know before I take it to a garage to get screwed?

what is the going rate to have the codes checked and reset? Should I take it to A chevy garage or try to find an independent outfit that works on Dura-Max?

I am in Oregon City Oregon right now.

Gary

I think the service 4x4 lite has to do with the switch assembly, mine did it a few times then never again. I've read on here that the assembly needs to be replaced, do a search. There are a lot of guys here who can loan you a code scanner, there is a sticky that lists people who will help, hopefully in your area. I bought a scanner myself.and use it a lot. It's nice to know whats going on before you take it to a shop. Good luck, ther is a lot of info on this site, keep us updated.

in addition to the switch assy the 03's had a problem with encoders in the transfer case .. at first it causes the service 4wd drive message in the DIC .. eventually the controls become inoperative ... best to pull the fuse on the 4WD if it persists to prevent getting stuck in 4WD-LO ..

How much does it cost to replace the encoder?
Is it a warranty item?
I now have 81K miles on this truck and it has been doing it sense I got it with 50K on it.

My 'Service 4wd' warning came on when I had my pump rub issues.

How much does it cost to replace the encoder?
Is it a warranty item?
I now have 81K miles on this truck and it has been doing it sense I got it with 50K on it.
Unless you have an extended warranty it's only covered under the 3yr/36kmi warranty

Almost any auto parts store will check the codes and reset it for free.

My 03 will throw all sorts of strange messages on the DIC about brakes, 4x4, and other stuff if the batteries are weak or a ground cable needs cleaning.

Hope this helps

Well I have it in the shop. They are up to $870.86 so far and counting.
They Did a transmisson Flush and Brake and steering flush, Replaced the Fuel Filter that I gave them and the Air cleaner that didn't look all that dirty but it was collapsed( it was an AMSOIL Air Filter) They are replacing a controler for the 4x4 encoder. We are hopeful that this fixes everything.

Ok Now we are up to $1100. They are also going to Change the front and rear and transfer case fluids. But I don't think any of those fluids were replaced when I got the truck with 50K miles on it and now it is at 81K so it needs it anyway.
What the hell it is only money I don't have. Maybe I can get the Gov't to bail me out.

Did they even check the codes? All the stuff they are doing is a good idea, but did it fix any of the problems?

I'll find out tomorrow. Yes they checked the codes and THINK/B][/U] This will fix it.

OK Final Bill $1129.91 That was for all the things I already wrote about and they say everything is fixed and Normal.
I'll find out when I hook up my trailer and head over the Mountains.
The Old Encoder Sensor (part # 88962313)$90.74 had a tiny bit of wear and the inside moved back and forth a little, they claim that was the service 4x4 problem and why if didn't show that it was in 2wd.
$95.60 Labor to replace the air filter and fuel filter. It can't take 5 min. to replace an airfilter and I'd say you can do a Fuel filter in 15 mins. or less.
Well thats a Chevy Garage for you.

the $1130 was a lot but it fixed all the problems and now I am getting 22.5 MPG on the road at 65 mph without my trailer behind me. Even going up to 5000 ft over the mountain pass. that is the best it has been in 30,000 miles.