4WD issues

[bobaphat2001]

Hey All..
I have been a member for a bit but I just sit back and read what I can and try to fix it without asking stupid questions. I have a 2003 Chevy Trailblazer LS 4WD. I have owned it for close to 3 years now and it has been a good truck to me. My issues began last winter. My GF is a nurse and works 3rd shift. We live in NH so snow is nothing new. Well I had to drive her to work and pick her up after her shift in the middle of a blizzard. I drove her to work with no issues and even enjoyed the fact that one the way I had to drive up a hill that 6 people had pulled over to the side and were doing their best to get to the top. I had it in 4HI and drove right past all with out an issue. I got her to work and then drove home. I had to pick her up the next day so I started the TB up and let it warm up a bit. It had snowed all day so I just figured I would switch it into 4HI and go get her. Well I switched it into 4HI and I got the service 4wd light and was stuck in 2wd. Needless to say it was one hell of a ride to get her in 2wd. I searched the forum and ordered a new dash switch. Switch was installed and the same thing happened. It worked a few times and then it did the same. I switched it into 4HI and I got the service 4WD light and was stuck in 2WD. I realized that the majority of the time I wouldn't get it into AWD before I got the Service 4wd light. I limped by the rest of the season.

This season I ordered the TCCM and figured the problem was solved. I had the original "flaky" TCCM #12584313 so I replaced it with a TCCM from a 2005 GMC Envoy. The system will now shift into AWD without issues and will shift into 4hi. I will sometimes get a service 4wd light when it goes to 4hi and sometimes I only get a service 4wd light when I try to continue to 4lo. Either way, I now get a light 99% of the time when I try 4lo. Once the system has given me a service 4wd light, I will loose the lights on the selector switch. The system will be this way for a little bit and will eventually change back to normal after a little bit of driving and a engine shut off or two. Once I get the lights above the switch back the service 4wd light will be out. It will stay out until I go to 4lo.

I have replaced the dash switch, installed a used TCCM, and cleaned the front axle actuator. What else should I try?

 

[littleblazer]

I believe there may be something with the transfer case encoder motor? I'm not too fluent on the 4wd system since... well I haven't had to mess with mine. Also has the fluid ever been changed? It's supposed to be lifetime fill but in reality it's service life is about 50k miles. Someone who knows more will be around shortly I'm sure.

 

[djthumper]

What other service work have you done to the 4WD System? How many miles is on the vehicle? If you know the TCCM is functioning properly and you have done a fluid change in the transfer case I would look at the disconnect. Here is a link where I posted a link to troubleshooting steps recently. http://gmtnation.com/forums/threads/bravada-awd-not-working.14622/#post-477237

 

[bobaphat2001]

That is all the work I have done to the system. I have not changed the fluid in the transfer case because I thought that once it got higher up in the miles it was bad to change it. I change the oil regularly. It has 189,000 miles. I believe the TCCM is working correctly.

 

[Mooseman]

Quite the contrary. The TC fluid MUST be changed at 50k miles. You were probably thinking of the transmission but that is also an "old wives tale". Change the fluids as required.

Here is an article at our sister site ORTB
http://www.offroadtb.com/articles/tech-docs/what-is-wrong-with-my-4wd-system/

And I'm sure there are lots of other articles there that talks about the 4x4 system. If I were a betting man, I'd be looking at the encoder motor next.

 

[smt 59]

Wow, when you change the TC fluid take pics for all to see, I would change and run for a month and change again to clean it right out.

 

[bobaphat2001]

Ok, guys..

I'm gonna go pick up the fluid I need to change the front diff. and the transfer case fluid. From what I have read so far, I will need to get 2 quarts of GM Auto Trac II fluid and one jug of SAE 75W90 Synthetic Axle Lube.

Is that correct? I talked to the dude at the stealership today and he was saying the transfer case would need 2.2 quarts instead of the 2 quarts most people here have said they used. If I need to buy 3 quarts, fine no worries.. but I will not be too pleased if I buy 3 and only need 2. Kinda pricey at $10.34 a quart. The SAE 75w90 GM stuff is $27.90 a jug. I called 2 different dealerships and the price for the Auto Trac was the same at both, but the SAE 75W90 was $23.98 at one place and $27.90 at the other. The guy said he would sell me one for $20 bucks if I just needed one.

Thanks for the info in advance!!

 

[bobaphat2001]

I got the TB with 153,000 on it. For all I know the fluid could have been changed 3 times already or none at all. I will take pics and post them up when I get this done.

 

[smt 59]

You will be fine with 2 bottles of the Track ll , when I change mine I have a little left over out of the 2, what is the name brand gear lube they are selling?

 

[bobaphat2001]

Both the Auto Trac II and the Sae 75w90 are a GM product. Which would be the gear lube? the axle lubricant or the transfer case fluid?

Thanks, smt59

 

[smt 59]

Track ll for the TC
Gear lube for the dif.

 

[smt 59]

Make sure the gear lube is synthetic.

 

[Mooseman]

The AutoTrac II is the only one from GM/ACDelco. 75w90 can be any brand as long as it's synthetic.

 

[littleblazer]

I too can say 2 quarts is enough for the T-case. Maybe if you let it sit for hours it may need a bit more, but I drained mine for 20 minutes and 2 was just enough to make it drip out the fill plug.

 

[bobaphat2001]

Awesome, that helps me a lot. I knew I had to get the Auto Trac II from a dealer but I didn't know I could use any 75W90 as long as it was synthetic. That makes it a whole lot cheaper to do. Thanks a lot for the confirmation of the 2 quarts.

 

[Wooluf1952]

Welcome

In case you haven't heard:
http://gmtnation.com...eres-the-story/

The Auto-Trak II is sold in one liter bottles. Two bottles has been more than enough for my '03. Had some left over both times I changed mine.
I've also seen it sold at auto supply stores. But it was about the same price as the dealer.

 

[smt 59]

FYI,
CAPACITIES:
Engine, with filter..........6.6 liters [1] I6 Engine
Cooling System, Extended Initial Fill..........13.1 liters
Passenger Car & Light Truck Antifreeze & Coolant
AMSOIL Antifreeze and Engine Coolant
Cooling System, Standard Initial Fill..........10.2 liters
Passenger Car & Light Truck Antifreeze & Coolant
AMSOIL Antifreeze and Engine Coolant
Automatic Transmission, 4L60-E Initial Fill..........4.7 liters
Automatic Transmission, Total Fill
4 speed 4L60-E..........10.6 liters
Differential, Front..........0.8 liters
Differential, Rear..........1.7 liters
Transfer Case, NV120/126..........1.8 liters
Transfer Case, NV226-NP8..........1.8 liters

 

[bobaphat2001]

This was the front diff. fluid. This stuff stunk! I replaced without an issue.. except I found the nylon washer in the old fluid AFTER I had put the plug back in and filled it up. I then drained my oil catcher and drained the transfer case. This fluid did not stink but it was dirty. It looked more green than the original blue. I filled it up with new Auto Trac II. Both fluids had the same tiny usual metal residue as old motor oil sometimes does. By the time I was done with this I was out of sunlight. I had started pretty late in the day when it comes to sunlight this time of year here. The TB is in the driveway still on jack stands so I can check out a few things tomorrow and install the new spare tire holder and the spare tire. After that I will give the 4WD a try. Anything I should look at while it is up on jack stands before I take it down?

 

[Mooseman]

That is waaaaaay past its best before date. I've never seen it that bad. That second rinse was probably not a bad idea given the condition of the old fluid to flush as much of it out as possible.

Maybe check your diff fluids and give the u-joints a once over. Hopefully the TC isn't FUBAR because of the fluid.

 

[bobaphat2001]

yeah I am planning on changing it again soon. That pic is of the front diff fluid. It stunk like crazy!!!!

I didn't take a pic of the TC fluid. It was no where near as nasty as the front diff fluid though.

 

[littleblazer]

Differential fluid smells horrible. Always.

 

[bobaphat2001]

lol.. I did not know that, Littleblazer. That stuff started draining, I got it all over my hand and I was like, "wow.. that friggin' reeeks".

 

[Mooseman]

Normal gear oil smell. I thought that was the TC fluid but I have seen diff fluids like that when it's been really neglected.

 

[littleblazer]

My diff fluid was black water lol. Well the front. The rear was still good.

 

[bobaphat2001]

I thinking about doing the rear diff. and then the transmission probably.

 

[littleblazer]

Yours should be easy. You should have an actual drain plug on the rear.

 

[bobaphat2001]

Update: I took the encoder motor off the other day and I cleaned it out. I cleaned all the copper contacts and wiped down the magnets. I put it all back together and I was able to turn the switch to 2HI, AWD, and 4HI and the system shifted fine for 2 turns. I never tried 4LO. I just switched from one to the other and listened to the system do its thing.
Feeling all warm and fuzzy and stuff, I left to get my son at Driver's ED. I decided to take a victory lap so to speak as I was driving.. LOL I flipped the switch to AWD.. Check.. no problem, like usual.. and then I flipped it to 4HI doing maybe 30 MPH.. Blink.. blink.. SERVICE 4WD light nice and bright...

Needless to say that took all my warm and fuzzies away and I spent the rest of the ride thinking. I believe the issue is the front axle actuator. I am starting to believe this piece is acting a bit flaky... It has rained the last 2 days so I have not been able to check my hunch. I will come back with the findings.

I am planning a nice ride to a certain salvage yard about an hour from my house in the near future (After the Holidays). They will probably have a few of our platforms out back and I can "go pickin". I will try to snag an encoder motor or two and the same for any TCCMs 2005+ and any axle actuators I can find. There is a couple other things I hope to find there, but I am not holding my breath..

 

[Big B Jantzen]

You can switch into 4 at that speed? I thought it was suppose to be no more than 2 to 5 mph??... I am new to 4x4 so I could be way off here lol...

 

[Mooseman]

Even says so in the owners manual that you can switch up to 50MPH IIRC but WE recommend much lower speeds and certainly not on asphalt.

 

[TollKeeper]

I have the same problem with my envoy. Encoder is factory original, and verified working. TCCM was replaced last year. Dealer tells me it's the from diff actuator. And their is am easy way to diagnose. If it's called out, start the truck and flip to 4hi. If service 4wd comes on, turn switch back to 2wd, shut truck off and wait 2 minutes. Restart truck and either let idle for 20 mins, or drive around at city speed for 20+mins. The idea is to get the grease in the actuator warmed up. Now switch to 4wd. If it switches, that means its in the actuator, at least that is what it means die me.

I plan on replacing my actuator when I swap my diffs.