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Discussion Starter · #1 ·
I have a 2002 Chevy Duramax that is now stuck in 4LO. I was driving it this morning at about 55 - 60 MPH and the Service 4WD Light came on briefly, it then slammed itself into 4LO. (How is that even possible?) After a brief moment of terror and hearing alot of nasty "ratcheting" noises, I pulled to the side of the road, placed the shifter into park and shut down the engine. I then restarted the truck to listened for noises. Everything sounded fine in Park,neutral and drive (at rest). 4 LO shifter light is lit and will not transfer into any other setting. I limped back home (3 miles) in 4Lo. The thing will not shift back out. Also, in Reverse, it will go about 10 feet, then coast to a stop...the R on the Column indicator will then start to flash. Can anyone advise me on what I should do? Thanks in advance for any help.
 

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it should have neve evn done that but it must be a electrical problem like a solenoid or something
 

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do you have anyway of checking what code it has thrown
 

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What were the RPM's doing 60 and in 4 lo?.I didnt think that could be possible.
 

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Discussion Starter · #7 · (Edited)
I couldn't tell you what the RPM's did, I was to busy eating the stearing wheel !!! -:t Not really, but all happened so fast that I had no chance to look at the tach. I just heard some really bad noises...not sure if it was tranny or transfer case, but noises were not pleasant sounding. Everything seems to sound OK now, but I can't get it out of 4LO to take it back up to speed to see if I have any other problems. Talked with the local dealer and he said it was probably caused by the push button selectors shorting out...or one of the two modules associated with the 4WD. I just hope when I check the tranfer case, that I don't see little shiny things come out!
 

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I couldn't tell you what the RPM's did, I was to busy eating the stearing wheel !!! -:t Not really, but all happened so fast that I had no chance to look at the tach. I just heard some really bad noises...not sure if it was tranny or transfer case, but noises were not pleasant sounding. Everything seems to sound OK now, but I can get it out of 4LO to take it back up to speed to see if I have any other problems. Talked with the local dealer and he said it was probably caused by the push button selectors shorting out...or one of the two modules associated with the 4WD. I just hope when I check the tranfer case, that I don't see little shiny things come out!
Hope you have a warranty!!
 

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i dont know whatll do, if there are any codes stored, but you might try pulling the 4x4 shift fuse on the side of the dash...
 

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This has happend before, but I can't find the post about it.
 

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Discussion Starter · #12 · (Edited)
Just got back from the dealer. They say they'll have it fixed by Thursday. According to them it is a 2 part problem. Part one is that the 4wd sensor went bad. Part two is that the 4wd decoder motor also went bad, sending it into 4wd. Seems kinda dangerous to me to have a system that could possibly allow a truck to automatically shift itself into 4LO when something goes "wacky". Should have a safeguard for that kinda thing, or maybe just put a stinkin' shift lever back into them and forget about all of the fancy pushbutton stuff. The glitz and glitter is nice and all, but apparently not very safe OR reliable. As for the New Showroom Furniture I'm buying the dealer....$1000.00 and counting. They haven't even checked yet to see if there is any transfer case gear damage yet. Look's like Top Ramen for dinner for the next few months. The wife and kids will love that news!
 

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have you had any 4wd messages in the dic in the past and have it documented?? There are some TSB's out for this, but i dont think anything saying gm covers it...<surprise surprise huh..
 

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Discussion Starter · #14 ·
I've only had the truck for 2 weeks...I am in Idaho and we bought it out of Texas. As usual the Dealer said "This things Cherry...No Problems at all." As far as the Service 4WD in the DIC, nothing all the way from Texas....Last 3 days that I've had it, though, the DIC flashed maybe 6 times. Each time it would only flash 1 time for about 1-2 seconds. Just long enough that you could read it, and then it would disappear. I didn't have a chance to get it checked out. To be honest, I figured that if it wasn't flashing or on constant, it was nothing major....just a minor problem starting to occur. Boy was I mistaken. Also, the DIC would only flash when I was taking the shifter from Park to another gear. And it would only do this maybe 10% of all shifts. In three days time I didn't shift it enough to get more that 5-6 indications. That's what made me think it wasn't that urgent. If anyone out their is getting this type of indication to Service the 4WD. Take caution, it is very expensive to ignore.
 

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Sure hope this isn't a flood vehicle. Would the sensor and decoder be affected by water?
 

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Is the dealer in TX responsible for anything?
 

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Hey it could be that the thing needs to be woke up so to speak. Its a problem sometimes that when you turn the truck on, the sensor does not tell it to wake up or work. There is a TSB about this for the Avalanche. All they do is hook up the tech II and tell it to work, and it resets the codes for it to work properly.
 

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Discussion Starter · #18 ·
Hopefully, I covered my bases on the Flood issue. I made the dealer (in the paper work) guarantee that it was not a flood vehicle. Also, did a CarFax and nothing at all negative came from that. The truck is really in awesome condition as far as I can tell. What I know nothing about are the electronics, and so far that what has been the problem. From other reading on the internet, the problem I am having is fairly common, as far as the thing not coming out of 4LO. My new twist to this story is that mine shifted into 4LO from 2HI. Many others have had problems not being able to get their truck out of 4LO once they put it in. My brother-in-law had a 2000 Chevy Silverado that did just that. As far as the Tech II, the dealer put that on and was able to tell that the sensor was bad. Then upon further diagnosis, he traced the problem further to the Decoder Motor. As far as the dealer being liable, I don't know if I have a leg to stand on. I bought it AS IS - NO WARRANTY. So I think, it's my baby now. I paid my nickel an took my chances.
 

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...or maybe just put a stinkin' shift lever back into them and forget about all of the fancy pushbutton stuff. The glitz and glitter is nice and all, but apparently not very safe OR reliable...
Yep, my thoughts exactly. That is why I specifically looked for a truck with manual 4wd. I know I can't accidentally get mine into 4 lo while going down the road.

Sorry to hear of your troubles, though. Good luck.
 

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Discussion Starter · #20 ·
Current status...still Dead in the Water. Just got a call from the dealer and here is the latest diagnosis:

1st Sensor - Bad and Replaced ($275 plus Labor) - replaced Wednesday.
After this was replaced they were able to tell that the Encoder Motor
was bad.
Encoder Motor - Bad and Replaced ($575 plus Labor) - replaced Thursday.
After this was replaced they were able to tell that the 3rd Sensor (unknown
name at this point) is bad. Now they can send off for it and start to
replace it on Friday.
3rd Sensor - Bad and being Replaced ($378 plus Labor)-being replaced Friday.

I curious as to how many of these friggin' sensors are on the bad boy!

Wow these Duramax's are spending little buggers 'eh!!!!

If anyone knows how these 2 sensors and encoder motors work and relate to one another, I could sure use the lesson. Thanks!
 
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