Service 4wd - C0327

[johnnyreb]

2005 Tahoe Z71. I've been having the service 4WD drive light problem since 29,000 miles. I'm now at 55,000 miles. This is the third time it's been in the shop for this problem.

 

Here are my service records for each time I took it to the dealership because of the light being on...

 

29,000 miles (12/29/06) - code C0327 stored. followed TSB to ground G110 on frame. Cleaned ground and reinstalled. cleared codes and rechecked all connections at TCCM. all ok.

 

44,700 miles (10/22/07) - no failure codes stored. needs re-programmed. re-programmed transfer case module.

 

55,300 miles (8/15/08) - found DTC C0327 in TCM. Followed Diag. Encoder Motor not closing.

 

The latest estimate for repairs is $758.64 to replace the transfer case encoder motor. I told them not to do the repair, that I wanted to do some research on it before proceeding.

 

This is an intermittent problem - it comes and goes. Early this morning the light was on and I was unable to switch the vehicle into 4WD - the 2WD light was on and it wouldn't switch into any other gear.. Then I went out and started it up again a couple hours later and 4LO light was flashing. Shut off the vehicle and started it up again a few minutes later and all of the lights were out. I just recently had the vehicle out about an hour ago and it worked fine - I was able to switch into 4HI and back into 2WD with no problem at all.

 

I'm not convinced that the motor is bad. I'm leaning towards the sensor in the motor. I've read numerous posts on here and on other GM forums that say that sensor is the most likely problem. I've also read that the switch on the dashboard could be bad. My understanding is that if the C0327 code is present, then it's not the switch. So I'm steering away from replacing the switch.

 

If I replace the sensor, is this going to solve my problem? The dealership said they would replace the sensor for me but he said that the motor is still not going to work properly, but he didn't really give me a good explanation for replacing the whole motor other than that's what C0327 requires.

 

I'm considering taking it to another GM dealership to see if they give me the same result.

[5Alive]

I went through this issue with my 2005. I documented it thoroughly on the web, mostly on another GM truck related message board under a different user name, so it is quite possible that some of the research you read online was written be me as well.

 

If the repair were warranty work to be reimbursed soley be GM, you better believe that your dealer would just be replacing the sensor first, not the whole motor. But since your case is customer (you) pay, they can make more money on replacing both the motor and the sensor, due to the markup on the extra part, and a faster repair, since there is no dissassembly and reassembly of the sensor enclosure. They can also better assure themselves that you won't be a come-back in case the sensor change didn't work. That's giving them the benefit of the doubt though.

 

The new sensor alone fixed my C0327 period. It's been a year and a half, maybe two years now, time flies. No more Service 4WD msgs. Same old encoder motor, just a new sensor.

 

On edit, that all being said, I reread your post, and essentially you are requesting a crystal ball guarantee by asking "If I replace the sensor, is this going to solve my problem?" There are no guarantees that it will work in your case, but there is a consistent pattern of evidence indicating that it has worked in a lot of similar cases for similarly equpped trucks of the same range of model years.

 

The dash switch issue had more prevelance in earlier model years (2000-2003). The encoder motor sensor issue seems to afflict 2004-2005s. These conclusions are all based only on anecdotal reports from forum posters, like us, not on scientifically reduced statistical data from GM.

[johnnyreb]

Did you do the repair yourself?

 

Do you happen to have the procedure for replacing the sensor? Is it simply removing the motor from the transfer case, disassembling, replacing the sensor, and re-assembling? Are there any steps involved after the sensor/motor is reinstalled to clear the codes or to get the vehicle to recognize the new sensor?

[5Alive]

Although the following is NOT from actual experience, here is a rough guide of what the job entails after you raise and safely support the Tahoe with jackstands and remove the transfer case shield, if you have one:

 

First task is to remove the front driveshaft. You'll need special boot clamp pliers to reinstall the boot. There may be two clamps on the boot to crimp. To get them off, you'll need a thin flat bladed screwdriver to pry. Remove the double clamped boot clamps at the transfer case side first, but when it comes to actually removing the driveshaft itself, drop it at the front axle yoke side first. If a single clamp boot, then you can disconnect it from the groove on the transfer case output shaft once the front drive axle shaft end is partially lowered, as you are pulling the splined shaft out of the case.

 

BE SURE AND MARK THE POSITION OF THE DRIVE SHAFT relative to the transfer case output shaft as well as the front axle pinion yoke. Kind of important, these marks, so that you'll be able to reinstall the shaft correctly, in phase, and so that whatever engagement mojo that is in the front axle is clocked correctly with whatever shift mojo is in the transfercase.

 

When pulling out this driveshaft, resist the temptation to pound on the yoke ears, and resist the temptation to pry between the yoke and the universal joint, to keep from creating hairline fractures at the injection joints that would lead to a more spectacular driveline failure down the road.

 

Later on, after you're done with all the other work that is in store for you on the encoder motor, you will want to have NEW clamps, a clamp installation tool (google J-43218 to see what GM's looks like), and output shaft lubricant for the splines that meets GM specification 9985830.

 

Now you can remove the encoder motor assembly. There are two electrical connectors to unplug: 1. The Transfer Case Switch connector, and 2. The Encoder Motor connector. You'll need flexible arms and a small flat bladed screwdriver to release the retention tang of the connector. There is a lot of heat down there, so these plastic connectors can become quite brittle. It is easy to break the retention tangs, so care is required.

 

Now, just 3 bolts and the encoder motor is free.

 

Here is where it gets sticky... I think the encoder motor is like a clock... whose hands must be in the right position in order for the rest of the front drive components to know what time it is. This indexing aspect is important enough that were you to replace the encoder motor, you would have to first manually shift the transfer case into NEUTRAL... by using a crescent wrench on the shift shaft. Of course, then you would need the experience to know what exactly is neutral on the transfer case, without benefit of indicator lights to tell you. I don't have this experience.

 

But since you are not replacing the encoder motor, then you may not have to shift the transfer case in this manner, as long as you don't rotate any rotatable parts that are exposed once you remove the encoder motor. Again, I haven't seen what is exposed myself, but have a strong premonition that if anything is movable inside a hole in the encoder motor, it shouldn't be moved carelessly. Kind of like moving the hands of a delicate clock the wrong way. But that is just a premonition. There are timing marks inside the encoder motor that index and align the gears, if that gives you an idea.

 

There is an actuator insulator gasket that becomes exposed once you pull the encoder motor, and that is supposed to be replaced with a new one anytime the encoder motor is removed. Speaking of more parts that are supposed to be replaced, once you have the encoder motor safely on your work bench ready for surgery, there are 4 screws you will need to remove... two in the motor cover and two in the casting on the edge. All 4 of these screws are to be discarded and replaced with new ones. Once you remove the encoder motor cover, there is an orange rubber seal inside the cover that is also to be discarded and replaced with a new one. The shim on the output gear can be saved and reused.

 

I'm sorry, but I don't have any part numbers for the orange seal, the 4 screws, the actuator mating seal, or the new boot clamps that you'll need to correctly do this job right. I do have a strong suspicion that my dealer did NOT correctly do the job right, as my repair order only shows 1 part, the sensor itself, and doesn't show ANY of these other parts that needed to be discarded and replaced with new ones. Short cuts seem to be the norm at most dealerships.

 

Finally, the operation can begin. Remove the output gear. Disconnect the wire harness that tethers the encoder. Remove the encoder from the output shaft. Tada, you've got to your donut... the encoder sensor. Now toss it and plug the NEW encoder sensor that you bought into the wire harness. There is a legend that says "TOP", and you'll want to make sure the enoder part number is facing up.

 

When you mate the encoder sensor to the output shaft, be sure to align the encoder tab with the keyway groove on the shaft. Everything is clocked, indexed, as that is what this group of parts does... it reports shift position to the rest of the truck. After seating the encoder onto the output gear, place the assembly back into the casting. There is a slot for the grommet harness in the casting, and the flat area of the grommet should face up.

 

Now is the time to make sure the timing is right. Align the casting and output gear timing marks at the same time you align the two encoder phasing posts, while inserting the shaft into the bushing and verifying that the output gear and the idler gear are engaged properly. Seat the wire harness into the channel, and put the shim you took off earlier back on to the output shaft gear.

 

Put in your NEW orange gasket, and install your NEW screws, torquing the two short ones to 18 INCH lbs., and the two longer ones to 26 INCH lbs.

 

Reinstall the encoder motor reusing the same 3 bolts, and connect the two wire harnesses you unplugged earlier.

 

If you have a double clamp boot, install your NEW clamps onto the grooves of the prop shaft boot before you place the prop shaft into the splines of the transfer case output shaft. If you have a single clamp boot, you'll do the same thing without the first clamp.

 

Remember to align the shaft with the reference marks you made prior to removal. After the spines are slid into the transfer case, line up the front end of the shaft with the front axle yoke and install the yoke retainers. Moving back to the transfer case, for both styles of boots, stretch the boot onto the transfer case output shaft until the boot snaps into the groove. Crimp your clamp(s) to 1.5mm head gap.

 

Resist rotating the driveshaft at this point. There is no solid fact behind that caution, other than the clocking mojo that is inside the encoder and front drive line actuators. My code CO327 appeared soon after I hand rotated my driveshaft during an oil change, trying to see if the front driveshaft was made in China, like the rear driveshaft was. I have no way of knowing for sure if this hand rotation set the stage for having to replace the encoder sensor or not, but I'm not willing to find out by doing it again either. Folks that have any other transfer case (241, 241HD, 261, 261HD, 261SHD) other than the AutoTrak 246 may not have this issue. We may not have this issue either. But why tempt fate?

 

Reinstall your transfer case shield, if you have one.

 

Pray.

 

PS... You did remember to take pics for us during this entire process, didn't you?

[5Alive]

Oh, forgot to address the last part of your question... no, there is no scan tool recalibration required.

[johnnyreb]

As a follow-up to my original post....

 

I chose to do the repair myself. I ordered the parts from GMpartsdirect.com. Part number for the sensor was 88962315 ($59.80). It took all of 90 minutes from start to finish. It's simply removing the motor from the transfer case, removing the motor housing, unplugging the old sensor, plugging the new sensor in, and reinstalling the motor.

 

There was no need to remove the driveshaft. And I found that it didn't come close to the complexity outlined in 5Alive's post (although, thanks for all of that info). I didn't replace the gasket or any screws. All I did was swap out the sensor and put the motor back on the truck. My only suggestion would be to make the location of the gears on the inside of the motor when you have it disassembled. I don't know that you could put it back together the wrong way, but I just put a mark on the gear positions relative to each other just in case.

 

After replacing the sensor only, my issue is resolved.

 

Sorry, but I wasn't able to take pics as I was doing the procedure.

 

Now for my rant...

 

I spent nearly an hour on the phone with GM customer service prior to doing the repain myself complaining about this problem. In the end they offered to pay 50% of the total repair - which still would have cost me over $400. They insisted that the whole motor needed to be replaced and would not budge from their position. They continually told me that they were committed to 100% customer satisfaction and that they would work with me until I was 100% satisfied. I told them that the only way that I would be 100% satisfied was if they (1) paid for the full price of replacing the whole motor, or (2) paid for the full price of replacing the sensor only. They would not pay for replacing the sensor only because they said it was not an authorized GM repair.

 

Of course they are very hesitant to accept the fact that this is a widespread problem with GM trucks that is discussed on almost all GM/Chevy forums that I've visited. I told them that I've visited dozens of GM message boards and it's well known within our community that replacing the sensor is the most sensible course of action.

 

I ended my call with them by saying that I would be doing the repair myself and that I would be posting my entire experience with this issue on all of the Chevy/GM forums on the internet. I also told them that I've been a Chevy owner all of my life (which is true) and that I will be very hesitant to ever purchase a GM vehicle again after this experience. I will also be emailing a similar rant to all of the parties involved at GM.

 

Please let my experience act as a guide. If you get this code and your vehicle is out of warranty, DO NOT LET THE DEALERSHIP TELL YOU THAT THE MOTOR NEEDS TO BE REPLACED. Buy the sensor for $60 and do it yourself.

[satori]

Excellent stuff! Just the other day I got my hands on the service history for the '05 Tahoe I just bought, and it was a little worrysome to see that this sensor had been replaced 4 times in the last 3 years. Sounded expensive to me, and with it now out of warranty, I wasn't looking forward to the next inevitible failure. This whole thread just made my day to see that it's cheap and it'll be easy to do myself.

 

(I'm assuming it's the same sensor... The repair entries just say, "SENSOR ASSEMBLY, TRANSFER CASE RANGE SELECTOR - REPLACE" Sound like the same thing?)

[minibike132]

Yawn, I love these conspiracy threads. The op states

 

If I replace the sensor, is this going to solve my problem? The dealership said they would replace the sensor for me but he said that the motor is still not going to work properly, but he didn't really give me a good explanation for replacing the whole motor other than that's what C0327 requires.

 

This sounds like a cover my ass warning. The person you talked to was probably a writer and they usually have about as much technical knowledge as a two year old has walking experience. The fact is a C0327 can be traced to a sensor, switch, motor and about 15 different ciucuits some of which don't even show up in the diagram, trust me I've been very surprised to find the ground terminal at the transmission connector (the one that goes directly into the case for the internal switches) being slightly spread out causing the code in one instance and even after knowing where I found the problem it was hard to back track and explain. That code is pretty vague, it's kind of like having a code that states the engine doesn't start. All the code means is the transfer case didn't do what it was supposed to do. Thats a pretty hard thing to guess at when you can't make it happen. Experience says it could be tons of things but it's usually the sensor or motor. Experience also says which ever one I sell, if I was not able to verify and diagnose the problem, it will be the other one and the customer will not be happy. Experience also says if I tell 100 customers I couldn't reproduce their problem so whatever I do is a guess that 90 are going to be pissed. This gets lost in translation between the tech, the writer and the consumer. There are a ton of things you can do to check for intermittants but the question is who is going to pay for it because alot of times you can do over the top testing on a circuit that isn't currently malfunctioning and not come up with anything at all.

[epiphaknee]

There is a Technical Service Bulletin on this problem:

 

TSB 03-04-21-001D

 

Also, an excellent step by step video at:

 

http://www.youtube.com/user/realfixesrealf...u/8/kldd1fu_csY

 

good luck

[hzl6cm]

I know that this was an old thread, but just wanted top say that it works great! Just changed on the encoder ring ring on our '05 Yukon transfer case motor and the 4wd now works perfectly for the first time in a year. I got the AC Delco encoder ring and gasket from Amazon for under $60,with free shipping. There was no need to remove the driveshaft and no need for reprograming afterwards. I just put the front of the truck on ramps and crawled underneath. The video the one post refers to is excellent. I indexed everything, using a sharpie to mark the parts, that the guy on the video indexed and did not have any problem getting it all back together correctly on the first try!

[Joel Hanson]

This worked for me. I ordered the encoder motor sensor from Amazon, borrowed some ramps from a neighbor, used this YouTube link http://www.youtube.com/user/realfixesrealfast?blend=2&ob=1#p/u/8/kldd1fu_csY, and five hours later I was done. The five hours is probably because I'm a musician and not a mechanic!

 

If you use the video link watch it all the way through. Part of the reason it took me so long is that when I pulled the encoder motor off the transfer case I didn't know I was supposed to mark the direction of the gear sticking out of the transfer case and make the same mark on the encoder motor. The gears inside the encoder motor got moved a little and it wouldn't fit back together. It took a while to make the adjustment to the gears inside. Each time I needed to adjust it I had to take the encoder motor apart.

 

In the end, even for a newbie like me, this repair works. No service warnings on the dash. No shifting into 4h or auto 4 on it own. Thanks to those of you who posted previously!! $60 later it's fixed!!

[TapInBirdie64]

I am having this exact same problem on my '05 Tahoe. The service guy at a dealership told me it needed the encoder motor and the sensor and wanted to charge me $800. I had already read this post and I figured I could do it myself and just replace the sensor like one of the earlier posters advised. Especially since they have the Tahoe in their shop already swapping the motor (long story). Anyway, I wanted to watch the video that showed how to replace the sensor, but when I click it it just takes me to an opening video and I can't find the one I want. Can someone please provide me with a link to the correct video? Thanks in advance.

[TapInBirdie64]

Nevermind, I found the video. Now all I need is to get my Tahoe back from the dealership with my new engine (well, used but with half the miles as my original engine) and when the new sensor is delivered I can get this thing changed.

[The_Hamster]

Did all this myself yesterday. Only two things I would add.

 

1 - Take some time to use some contact cleaner on the big electrical connector to the encoder motor and use some dielectric grease on the outer shell of the connector on assembly. In an attempt to help keep water out. Lubes up the Gasket inside.

 

2 - I've had the front drive shaft off 3 or so times. Never marked or indexed anything when doing so. Never had an issue related to it. Obviously marking or indexing won't hurt if you have a concern though.

[br_549]

Updated Link to YouTube video: