Service 4X4 on screen 2005 Chevy Tahoe

[Rapolla79]

Codes are: c0306,c0321,c0327

[dblwizard]

I've been having similar issues with my 2006 Yukon. I had originally replaced the Encoder Motor but that didn't solve my problem. I then found a post, that I can't seem to find anymore, that said this problem can also be caused by a loose connection on the cable to the Front Differential. I moved the pins on this plug just slightly so that they would make better contact put the plug back in and wala the problem went away. Well for about a year. Then problem started occurring again. My mechanic read the codes and said it was the Encoder Motor, I don't remember what the code he gave me was. C0327 I think. Anyway, I told him what I had found the time before so he dissembled the plug and cleaned it up but that did not solve the problem this time. I called OnStar to have the read the codes and they say there are not any codes in the system. I'm going to have my mechanic read the codes again and see what he says. Any thoughts? Has anybody else had problems where OnStar couldn't read the codes?

[j cAT]

the c0327 is a code that refers to the encoder operation.

could be the motor/wires/fuses/connector/shorted wires/broken wires.

the transfercase fluid should be checked for color and level. bad fluid will cause the encoder to mess up/stick/bind/break internal parts.

transfer case fluid need be blue . if its black have you wallet ready.

[dblwizard]

Have you ever seen where OnStar diagnostics (GM Goodwrench On Demand Diagnostics) does not show any codes?

[j cAT]

Originally Posted by dblwizard

Have you ever seen where OnStar diagnostics (GM Goodwrench On Demand Diagnostics) does not show any codes?

if you have service 4wd light on then you have a code with this. possible that GM on star can only retrieve engine codes not drivetrain codes.

[dblwizard]

Originally Posted by j cAT

if you have service 4wd light on then you have a code with this. possible that GM on star can only retrieve engine codes not drivetrain codes.

Yep, 0327. Going to replace the Encoder Motor first as the one on there has a lifetime warranty and its not really that difficult a job. Next I'll start looking at the wiring harness. Any thoughts on where I could get one specific for the 2006? Because of all the "intermittent" issues I've had with this that is where my guess is the problem really is. I'd like to check continuity on those wires.

Thanks

dbl

[j cAT]

Originally Posted by dblwizard

Yep, 0327. Going to replace the Encoder Motor first as the one on there has a lifetime warranty and its not really that difficult a job. Next I'll start looking at the wiring harness. Any thoughts on where I could get one specific for the 2006? Because of all the "intermittent" issues I've had with this that is where my guess is the problem really is. I'd like to check continuity on those wires.

Thanks

dbl

what does the transfer case fluid look like ? I change my fluid every 40,000miles. the fluid should be blue. if the fluid is bad the encoder works harder to move. that harness is a tough one to replace. I would inspect for proper routing and that the loom protection material over these wires is in good condition.that the hold downs are being used to secure wires.

these wires are very fragile so go easy on them .

I would not know where you can get them . repairing this would be better . also under the fuse box should be checked for rodents chewing these wires.

[MOB916]

Puttin this topic back on the table...1st post on this forum & have read all the replies thus far.

2005 Tahoe Z71 w/110K trouble free miles--
Selector button cluster was not operating & we could not identify whether we were in 2H/Auto4WD/4H/4L.....most often would show us stuck in Auto4WD so we just had it replaced. At the same time recently (just prior to switch replacement) vehicle had difficulty going into gear intermittently. Checked trans fluid, topped it to ensure hot fluid level was correct & it seemed OK but we were still stuck in Auto4WD according to the button cluster (when it decided to light up). Now the new switch/selector works & all driveability is functional except when put in daily driver 2H mode...in which it now pops out of Drive and into Neutral when attempted to operate. Dealer now states we need to remove transfer case for $1047 to disassemble and "see what's wrong". Any educated ideas on this new twist? I've informed the dealer service dept to hold as the truck is there right now. It does operate fine at the moment, but is in Auto4WD....should I drive it outta there & find another opinion based on what I've been told so far? $1000+ to pull the case and disassemble for a "look" seems quite excessive.

Thanks in advance for any advice.
-MOB

**& just talked to them again....failure code was C0327!

[j cAT]

with what your saying here you best have them service the transfer case.

IF you take the time to read all that is here on this particular post on this issue you will learn much.

you have a transfer case and it has a special fluid . if the fluid is with 110,000 miles on it I will not be surprised if you will need a complete rebuild.

I would also take the time to read the owners manual as well.

the code is the encoder motor. that gets damaged from low/worn fluid.

you need to crawl under the vehicle to check it.

all drive train fluids require replacing every 40,000 miles.

[MOB916]

Thanks for the reply....

having read through not only this forum, but others very similar as well.....the issues have been very similar with the resulting problems being related to the encoder motor and/or sensor and/or electrical connections causing operational failures. What I find strange is that they're not even mentioning any these items as potential causes & are jumping right to yanking out & disassembling the transfer case with a hefty price to do it.

[j cAT]

Originally Posted by MOB916

Thanks for the reply....

having read through not only this forum, but others very similar as well.....the issues have been very similar with the resulting problems being related to the encoder motor and/or sensor and/or electrical connections causing operational failures. What I find strange is that they're not even mentioning any these items as potential causes & are jumping right to yanking out & disassembling the transfer case with a hefty price to do it.

some of those people don't know much about this . the encoder is damaged from old fluid . the encoder is a motor and when the motor cannot move easy it gets burned out. it will also blow a fuse 20AMP on some called the ATC . other modules its called something else.

replacing all drive train fluids means front and rear diff / transfercase and the transmission pan drop clean replace filter if dirty.

the rear diff you remove cover after the drain and clean out the gear box of the metal debris dust sludge..

those that know how to do this encoder , it can be done for 200.00 ..dealership will charge 800.00 or so for the encoder replacing, but you could have more than that , because if the internals are broken you will get this code as well.. black colored fluid usually means a re-build..

[MOB916]

Ok so here's my non-mechanic dumb dumb question.... How do I check the transfer case fluid for levels & coloration? I'm presuming there's no dipstick for that. I think I'm going to pick up the car & evaluate my options before authorizing any further ($1000++) services at the dealer service dept....

[j cAT]

Originally Posted by MOB916

Ok so here's my non-mechanic dumb dumb question.... How do I check the transfer case fluid for levels & coloration? I'm presuming there's no dipstick for that. I think I'm going to pick up the car & evaluate my options before authorizing any further ($1000++) services at the dealer service dept....

under the vehicle in the middle is the transfer case . it has a big shaft connected to it that goes to the rear diff. On the bottom you will see a drain plug. up above that a few inches you will see the fill plug. you unscrew the top plug I think it is 15 MM. then you stick a plastic tie rap/ty strap into the hole. it should be a blue oil and just below the hole on level ground. if some pours out no big deal. I fill to the top of the hole and put the plug back on . torque to about 15 ft lbs. same as a spark plug... never over tighten because the case can crack. if the oil is black then you will need have a shop check it out or you can have the fluid replaced and see if it still works properly.

so what did they say was wrong ? you ask about the fluid ???

I believe this 2005 uses the GM trac II fluid in this transfer case. the NNBS 2007 -14 , GM I believed changed it to the dexron VI.

when ever changing the fluids in these always check with the GM dealership using your vin # to ensure you use/or the repair shop puts in the correct fluid. and yes there are idiot repair / lube shops that will put in the wrong fluid.

[j cAT]

Originally Posted by MOB916

Thanks for the reply....

having read through not only this forum, but others very similar as well.....the issues have been very similar with the resulting problems being related to the encoder motor and/or sensor and/or electrical connections causing operational failures. What I find strange is that they're not even mentioning any these items as potential causes & are jumping right to yanking out & disassembling the transfer case with a hefty price to do it.

SO MOB916 how much did they screw you out of , to fix it ?

what did they replace ?