Service 4X4 on screen 2005 Chevy Tahoe

[upthereinthesky]

Originally Posted by j cAT

the transfrcase encoder motor is the weak component. the electronic control module rarely fails. I would say is is the encoder. this can be checked by measuring for a short or open.

Thanks, j cAT.

Is there a procedure printed somewhere to show me where the pinouts would be? Or, do I just unplug the wiring harness and check there? It's difficult for me to get to the underside. It would be nice if I could pop a plug up top somewhere to check for a short or open.

[j cAT]

the transfercase uses blue GM trac II transfercase fluid. you will need 3 qts. uses 2.25QTS. the fluid should be blue or a gray blue color. if black you will need a complete rebuild.

the TRANSMISSION USES DEXRON VI NOT DEXRON III. DEXRON III was removed in 2006 because it is a damaging acid creating fluid/ poor quality. cost GM too much in warrantee work so they no longer license this spec fluid.

recheck those drive train codes again. the computer module is how the jack up the cost. yes it is very possible its just a wiring problem , cheap if you fix it very expensive if they fix it because they will change everything else first ..you get what I'm saying here !

the encoder could be open or shorted. could be the encoder internal position sensor is messed up. could be the transfercase encoder fork is binding up preventing movement. shorts to the transfercase of the small wires from the fuse block harness.

[upthereinthesky]

Thanks again, J cAT. Great advice!

I'm still undecided as to how to approach this whole warranty issue. If the fluid is black, and I change it, will the dealer claim I had maintenance performed without his authorization and thereby void my warranty?

I think I'll just see how the fluid looks. If it's clean, that's great. I can live with that. If it's black, I think I'll phone the dealer immediately and inform him. I don't think any reasonable person would prevent me from changing the fluid in that event.

I think I'll go out and get another Onstar diagnostic right now.

Thanks again!

Bill

[j cAT]

Originally Posted by upthereinthesky

Thanks again, J cAT. Great advice!

I'm still undecided as to how to approach this whole warranty issue. If the fluid is black, and I change it, will the dealer claim I had maintenance performed without his authorization and thereby void my warranty?

I think I'll just see how the fluid looks. If it's clean, that's great. I can live with that. If it's black, I think I'll phone the dealer immediately and inform him. I don't think any reasonable person would prevent me from changing the fluid in that event.

I think I'll go out and get another Onstar diagnostic right now.

Thanks again!

Bill

If the fluid is black then I would not change it but return the vehicle to this used car dealer and get my money back. this to rebuild properly will cost 2,ooo.oo......

[upthereinthesky]

Sounds like good advice. What if the dealer refuses to take the car back? My only recourse then would be to allow him to service the vehicle. I would lose if I took him to court, if he performs according to the terms of the Warranty.

Of course, these are all "what-ifs". I guess one step at a time. Tomorrow morning I'll know more. Then, it's decision time.

So, Onstar still reports only a code of C0306. They said they have the ability to read multiple codes, and that is the only code showing.

I think in the future, I'll advise anyone looking for a used Tahoe to check the transfer case fluid first!

[j cAT]

Originally Posted by upthereinthesky

Sounds like good advice. What if the dealer refuses to take the car back? My only recourse then would be to allow him to service the vehicle. I would lose if I took him to court, if he performs according to the terms of the Warranty.

Of course, these are all "what-ifs". I guess one step at a time. Tomorrow morning I'll know more. Then, it's decision time.

So, Onstar still reports only a code of C0306. They said they have the ability to read multiple codes, and that is the only code showing.

I think in the future, I'll advise anyone looking for a used Tahoe to check the transfer case fluid first!

If you bring back for repair work give a written letter signed , with the defects. then make sure you bring another person as a witness.

have them give you at that time a work order. now you have dates and defects and witnesses.

IN massachusetts many get these issues of defects ,with new vehicles compenstated , when the seller does not repair the defects.
small claims court works quite well.


what happens if they take 2 weeks or longer to repair ? when does the coverage end ? with AAA have it towed down there vehicle OFF. that way mileage zero.

[upthereinthesky]

Great points. I wondered that myself. I don't know if AAA will tow it that far. We've been considering upgrading to AAA Premium, which allows for 100 miles.

[j cAT]

Originally Posted by upthereinthesky

Great points. I wondered that myself. I don't know if AAA will tow it that far. We've been considering upgrading to AAA Premium, which allows for 100 miles.

I have the AAA premium . I believe it is 100- 120 miles.

If the trac II fluid is black driving to the used car dealer you may get stuck. also just more damage.

[upthereinthesky]

Yes, it's 100 miles. There's a three day waiting period.

I didn't think there was the possibility of damage if I left it in 2Hi. But, of course, something's going to be rotating in there. Like maybe the input shaft and the attached parts.

Thanks so much for your advice!

Bill

[upthereinthesky]

Originally Posted by j cAT

If the trac II fluid is black driving to the used car dealer you may get stuck. also just more damage.

Well, the fluid's black and has a burnt odor. So I'll call the dealer and see what he says.

So the mechanic plugged in his $7,000 Snap-On diagnostic reader and got the same code as Onstar had read: C0306. He tried the 4WD and it worked! Auto, 2Hi, 4Hi, and 4Lo all working. Of course, the clunking sound when shifting in and out is quite pronounced. Like friggin Loud.
The message cleared itself as well, as well as the DTC. When I got home just now, I had Onstar run a diagnostic, and it came back clear. Go figure. I guess enough shutdown cycles had intervened for the computer to allow another try at shifting.

The mechanic said it would be OK to drive in 2WD.

He also said that all the dealers buy warranties on their cars prior to sale to protect themselves. Whether the end consumer purchases the extended warranty or not, the dealer is covered. If the consumer buys the warranty, so much the better. So, in my case, it won't cost the dealership anything to fix this.

We'll see what the dealer says now.

[Bazinga]

Greetings to everyone. I have a 2005 tahoe z71 with 39,000 miles. About a year ago i started having trouble with the service 4x4 and stability sys dis. It would rear its ugly head right after using the 4x4, the disappear after awhile. The other day the lights came on again and never went off. Anyway, after reading these posts and found them very helpful, especially the posts from jcat i started my troubleshooting process. I removed the encoder/transfer shift motor and plugged it into my 2003 yukon which also has the nv246 xnsfer case. The problem was duplicated on my yukon which verified the problem. I found on amazon a replacement encoder ac delco part#88962315 for $45. I realized that i could replace just the encoder as the motor worked fine. Here's the iceing on the cake, I disassembled the encoder, cleaned the contacts and re-aligned the brushes and viola! The shift motor works! Reassembled everything and test drive reveals the 4x4 is operating properly. I hope this can help many of you out of a bind. If you dont want to rebuild the motor Doorman has an aftermarket motor for $179.00 on Amazon part #600-910. Many thanks again for everyones input especially jcat. Btw this is my first post here.

[upthereinthesky]

Bazinga: That's terrific! You are good!

I agree: j cAT is great! He's been most helpful to me as well.

[chipnmeg]

I have a 2005 silverado 1500 Z-71 with 201,000 miles on it which i have been having a problem with concerning the 4wd. I have found others with sort of the same problem but there are always different details. MY problem is that intermittently, service 4wd will come on the message center and my 4wd buttons will not work. They are still lit, but wont do anything. Other times i will have the same message but the buttons will not be lit. And still other times, the buttons will be lit but the truck will be in 4 LO. I have some mechanical ability so I have started checking things out. I read on one forum that sometimes the soldered connections in the shift button cluster will be bad, so I carefully re-soldered all of those with no result. I have not yet taken it anywhere to get the codes pulled because my dealership wants $200 just to read the codes. I read that 90% of the time it is the encoder ring in the transfer case so I have also removed the shifting mechanism from the transfer case to get a look at the encoder ring. No luck there. I dont know how to "check it" to see if it is good or bad. I am thinking my only avenue is to buy a new encoder ring and replace my old one to see if that is the problem or not but i have read that they need to be "flashed". Would a dealership need to do this? Or is there a way that I can? Any thoughts or suggestions will be greatly appreciated!! If you see that I have done something wrong, please point it out.

[JFCalvano]

For what it's worth: About 2 years ago my 2005 Chevy Tahoe was having the exact symptoms described by "cory e" earlier in this post - warning messages about servicing the 4x4 system which resulted in having the dealer replace the cluster of 4x4 switches in the dash. Problem solved (for a while).
Today (after experiencing the other symptoms that 'cory e' mentions exactly,... stability control and 4x4) my 2005 Chevy Tahoe is going to have its Encoder Motor Sensor changed out at $452.02 (which I assume now is only the part).
Thank you Cory E!

[Rapolla79]

Hey having the same issue as the rest of you, but I replaced the Switch first, everything went well. It switched into 4wd, hi/low, switched out np's, then I drove it a few blocks in 4wd to get the fluids moving. The on-screen code came back on Service 4wd. Now I went to the dealership prior to changing the switch and they told me that these two parts needed to be changed: Encoder Ring and the Switch console itself, Both both parts for $185. After Switch was replaced as I said in the previous sentences, the error came back shortly after. Now I crawled under my Tahoe change the encoder ring, Great tutorial on youtube btw!!!, and then I get the message Se4rvice 4wd, then Stability Control... System Disabled, now I took it back to the dealership and they found 2 more codes after the change that the encoder ring is the issue... I'll get those codes to ya in a few... I also read somewhere else that you cannot move/start the vehicle until you launch the programmer to show that the encoder ring has been changed?? I wasn't going to pay $400+ in labor to fix something that took me less than an hour to do, and I wasn't told that I need to immediately program it neither.