4WD not working? Step inside.

[jballentine]

I found a totaled out 03 Envoy to get for parts. Will these be comparable for my 05 trailblazer??

 

[Playsinsnow]

I found a totaled out 03 Envoy to get for parts. Will these be comparable for my 05 trailblazer??

4wd parts?

 

[jballentine]

4wd parts?

Yes, mostly the disconnect. Mine on the 05 is broken.

 

[The_Roadie]

All 4WD parts are compatible, as long it's the 4WD TB or Envoy, not the full-time AWD versions of the platform. They have different disconnects and transfer cases. On the diffs, the only issue is choosing the right gear ratio of the three available.

 

[jballentine]

Okay this one is the 4x4 not all weel drive. I should be able to see the gear ratio off of the sticker in the door then correct? I can't remember what letter goes with what ratio though.

 

[The_Roadie]

I should be able to see the gear ratio off of the sticker in the door then correct?

It's in the glove box, but yes. It's on the RPO code sticker.

I can't remember what letter goes with what ratio though.

A problem easily remedied by a short search.

 

[jballentine]

Thanks I found it.

 

[jballentine]

The Envoy I found for parts won't work that code GT4 mine is GU6. Guess I will keep the search on or just buy one off some website.

 

[Envoy_04]

The Envoy I found for parts won't work that code GT4 mine is GU6. Guess I will keep the search on or just buy one off some website.

Just for future reference: GT4 = 3.73 ratio, GT5 = 4.10 ratio (SS trucks), and GU6 = 3.42 ratio. G80, of course, is the famous Eaton locking rear differential.

 

[IllogicTC]

Just for future reference: GT4 = 3.73 ratio, GT5 = 4.10 ratio (SS trucks), and GU6 = 3.42 ratio. G80, of course, is the famous Eaton locking rear differential.

The famous Eaton locking rear to some.

The infamous Eater-of-rear-differentials to others.

 

[Envoy_04]

The famous Eaton locking rear to some.

The infamous Eater-of-rear-differentials to others.

Note I never said for what it was famous.

For most drivers, with proper service of the fluid and trying to drive so that the locker doesn't engage with bone-jarring force (light foot on the throttle, folks) the G80 is a wonderful option that adds great value to the 4WD system of a vehicle. For heavy duty wheelers, it has been reported to be a bit light duty.

 

[IllogicTC]

Note I never said for what it was famous.

For most drivers, with proper service of the fluid and trying to drive so that the locker doesn't engage with bone-jarring force (light foot on the throttle, folks) the G80 is a wonderful option that adds great value to the 4WD system of a vehicle. For heavy duty wheelers, it has been reported to be a bit light duty.

Certainly makes me miss the Dana 60. Limited-slip and locker versions available, gear ratios as steep as 7.17 from the factory, the "Super 60" (3.75" axle tubes as compared to 3 1/8 regular tubes, 1/2" thickness), plenty of aftermarket support so you could toss in better shafts and universal joints, lockers and LS if yours didn't have it, even covers with heat sinks. Those were the days.

To upgrade the G80 you'd either need to custom-fabricate (which means knowing EXACTLY what you're doing), sift through no/little aftermarket support, or pay someone hundreds or thousands of dollars to do even light fabrication (like a heat sink) for you.

 

[silvertb4x4]

can someone post a pic of where these 2 actuator motors are at? I am only hearing one switching.

 

[IllogicTC]

can someone post a pic of where these 2 actuator motors are at? I am only hearing one switching.

It's dark so I can't get pictures, but I can give you very specific instructions.

The front axle disconnect is up front, of course. Turn your steering all the way to the right, then go to your passenger front wheel. You should see on the backside of where the wheel fits, a CV shaft leading further under the vehicle. Just follow that shaft, the disconnect is on the other end. The actuator motor itself is attached to this device (which itself is bolted to the side of the engine). It makes itself obvious by having a wire harness connected to it, and juts out from the disconnect itself. The disconnect is made of metal while the actuator shell is plastic. It's easier to see and get to if you actually remove the wheel.

The transfer case encoder motor is on the transfer case. Look under the rear of your vehicle, at the axle. From there, you'll see the drive shaft which runs from the axle toward the front. On the other end of that is your transfer case. It'll get obvious what it is once you get close to it, as there's also another driveshaft connected to it which goes to the front. There will be a big cylinder attached to the backside of it, pointing sideways and at an upward angle in relation to the vehicle, and has a wiring harness attached. That's the other motor.

What you'll be looking to hear is MUUUCH easier to hear with someone to assist you. You can put your head just under the vehicle behind either front tire. Jacking shouldn't be necessary if you can get down there without a creeper. With the vehicle OFF but the key in the RUN position, have your helper switch from 2HI to A4WD. You should hear a noise sounding like it's coming from the bottom of the engine (front disconnect), and another motor running toward the center-left of the bottom of the vehicle. Have them switch back to 2HI to test again, rinse and repeat how many ever times is necessary for you to narrow your diagnosis.

 

[silvertb4x4]

When I jack up the whole vehicle. Engage it to 4hi and put it in drive the front wheels won't spin and I hear a constant clicking noise coming from the front somewhere. Until I apply the brakes. What is the problem?

 

[IllogicTC]

When I jack up the whole vehicle. Engage it to 4hi and put it in drive the front wheels won't spin and I hear a constant clicking noise coming from the front somewhere. Until I apply the brakes. What is the problem?

If the clicking stops when you apply the brakes, perhaps the problem lies in the brake system.

 

[silvertb4x4]

But why won't the front wheels spin? Just clicking. 4low does the same thing. So it looks like the axle disconnect motor is bad then? When I take the actuator out and listen it sounds like it's working. So I hear both actuators when I switch from 2 hi to 4hi So my disconnect is either stuck or broke? Pretty sad with only 50,000 miles.

 

[IllogicTC]

But why won't the front wheels spin? Just clicking. 4low does the same thing. So it looks like the axle disconnect motor is bad then?

With both wheels in the air? Perhaps a screwed up front differential.

 

[silvertb4x4]

So I put it on the ground. Drove it, if I put in it 4hi while moving it engages. But won't from a dead stop. I'm thinking the front disconnect is messed up or not engaging correctly? Does this 4wd system have to be rolling to engage in 4wd?

 

[silvertb4x4]

With both wheels in the air? Perhaps a screwed up front differential.

WHen its in the air you hear a clicking noise from the front differential. The front driveshaft is turning.

 

[IllogicTC]

So I put it on the ground. Drove it, if I put in it 4hi while moving it engages. But won't from a dead stop. I'm thinking the front disconnect is messed up or not engaging correctly? Does this 4wd system have to be rolling to engage in 4wd?

Technically it can be engaged at a standstill, but the two halves of the axle would have to line up correctly on the collar. It'd be some low-percentage chance the splines line up perfectly, so a little movement will get that other axle clicked in.

WHen its in the air you hear a clicking noise from the front differential. The front driveshaft is turning.

I thought you said the tires weren't moving, though? Which tire are you spinning?

 

[chevman]

I just went through the same thing clicking and would not engage from a stop but if I was rolling it would engage and only 53,000 on my tb is was the disconnect got a new one and fixed the problem im 99.9% sure you have a bad/worn disconnect.

 

[silvertb4x4]

Chevman, Will yours engage from 2wd to 4hi while being stopped since you changed it? yeah thats what im thinking too maybe mines stuck or the fork is broke. Its just weird that it will engage while moving into 4wd. I had a trailer full of wood and was in 2wd and got stuck. I engaged it in to 4hi and it would not go into 4hi. i was pissed. Crappy design..

 

[IllogicTC]

Crappy design..

Almost makes me miss the auto-lock hubs on my early 90s Ford. At least they worked consistently I still say I wish there was a solid front axle option. Barring that, an option to have the AWD sleeve instead of the disconnect, and then have auto-lock hubs (or even manual lock, since those seemed much more durable anyway).

 

[silvertb4x4]

Technically it can be engaged at a standstill, but the two halves of the axle would have to line up correctly on the collar. It'd be some low-percentage chance the splines line up perfectly, so a little movement will get that other axle clicked in.



I thought you said the tires weren't moving, though? Which tire are you spinning?

I raised the front left like it said at the beginning of this Thread.. I don't get why it isn't locked like it says. Am I missing something?

 

[chevman]

yes it does now I found out mine would not engage when I got stuck in snow drift put in 4 hi, 4awd, 4lo and all I hear is a clicking sound do some testing and after I drive it for a bit it would engage but not from a stop now with the new disconnect no problems it locks right in I agree it is a bad design I bought one off amazon and installed it myself im now 99.99% sure it is your disconnect let me know how your repair go's

 

[silvertb4x4]

Thanks IllogicTC, Chevman, very cool to have good people on here to help. you wouldnt happen to have the part number would you? I see there's a post on here how to rebuild it as well. It doesnt look to difficult to change.

 

[chevman]

I went with the doorman unit here is the link

Amazon.com: Dorman 600-115 4WD Actuator Housing: Automotive

also atp makes one here is that link

Amazon.com: ATP 111001 Front Axle Disconnect: Automotive

 

[IllogicTC]

Thanks IllogicTC, Chevman, very cool to have good people on here to help. you wouldnt happen to have the part number would you? I see there's a post on here how to rebuild it as well. It doesnt look to difficult to change.

It takes some slight dismantling of your passenger side suspension, and some tools that wouldn't be found in the average kit picked up at Wally World (like a 36mm axle nut socket, technically 35 works with factory axle but may as well have the 36). I've read up plenty on it, and no, other than needing a tool or two that doesn't usually come in the average midrange set, it's not too terribly horrifying.

I can't recall the part number, or if they're still even made OEM, but Dorman and ATP also make them now.

Amazon.com: ATP 111001 Front Axle Disconnect: Automotive It says the original list price is $1000, yeah right trying to make it look like we're getting a super deal when a bit over $300 is actually about on the money.

Amazon.com: Dorman 600-115 4WD Actuator Housing: Automotive

Both about the same price, and really I'm not sure if either one is better than the other.

And you're supposed to jack up the front right (the passenger side) to test the one-wheel-off-the-ground part it may say left as in from your point of view looking at the front of the vehicle.

I'll leave a bonus link here for people, just in case.

Amazon.com: Dorman 600-103 4-Wheel Drive Actuator: Automotive This is a Dorman 4x4 actuator. If your disconnect is shelled out, you can remove and reuse your original actuator if it is working, saves about $50 that way.

And if people have a busted 4x4 disconnect and are looking to just upgrade to the AWD sleeve, here you go: Amazon.com: Dorman 600-116 AWD Actuator Housing: Automotive Another Dorman part, this is the AWD "disconnect."

 

[silvertb4x4]

Yeah I tried jacking the left and the right and it didnt make a difference. So it leads me to the disconnect is the problem. Is there anyway to make sure the actuator is working correctly? I can hear it, I took it out there is a bunch of yellow looking grease inside. Doesn't look old or black.

 

[chevman]

if you took it off and seen it working I would bet it is fine mine had the same yellow greese and I reused it with no problem

 

[IllogicTC]

An easy way to test the actuator is to listen for it. If your ears aren't doing so hot, you can try tapping into the feedback wire and see if it the signal changes between engaged and disengaged modes. Sometimes having it disconnected from the disconnect and testing may prove satisfactory in theory, but while installed it doesn't have the power to properly work the system (usually due to no/old grease. It congeals over time). But it doesn't hurt to try it that way to at least know it's operating. Having it pulled, and have someone turn the switch to or from A4WD to 2HI while you observe it.

 

[silvertb4x4]

So if I take it apart I should see something move in and out? If not it can be bad? it must be working because if im at a roll it will engage the 4wd. just not from a dead stop. Would be the disconnect is the problem I'm assuming. Probably needs to be taken apart and cleaned and regreased and checked over.

 

[chevman]

it is engaging while you are rolling then it is good it is your disconnect that is the problem just slap a new disconnect on and reuse the actuator and you'll be good to go

 

[IllogicTC]

So if I take it apart I should see something move in and out? If not it can be bad? it must be working because if im at a roll it will engage the 4wd. just not from a dead stop. Would be the disconnect is the problem I'm assuming. Probably needs to be taken apart and cleaned and regreased and checked over.

If you remove the actuator from the disconnect, yes you should be able to see the plunger move in and out.

Not clicking in from a dead stop is sometimes normal, but may be a sign of wear I've not seen reported yet.

A teardown on the disconnect could help you diagnose the problem better before dropping over $300. If it does not pass the flowchart test then it may be worth replacing.

 

[silvertb4x4]

Finally got to take the disconnect apart. The front 2 needle bearings were shot. I assume this is why it wouldn't engage, except when moving. There were needles all over the front half of the disconnect. I am ordering the bearings and seals Monday. I hope this fixes the problem. Everything else looked good. Actuators work properly. The grease wasn't even really that black. The fork was not cracked or broke. I guess we'll find out in a few days. I think a 2.5 or 3'' lift is next

 

[silvertb4x4]

So I got the bearings and seals, when looking at this diagram of the breakdown Offroadtb.com Front Axle 4WD Disconnect the bearing behind seal #1 is really loose when inserted. Like no hammering needed to install this bearing. Is this bad? or will it be alright? I'm in the middle of putting it together right now. What should I do?
I looks like the aluminum has been worn away is why the bearing is basically falling in. Should i just order a new disconnect? This sucks. Why is it worn out with 50k miles. Which housing would i need? 12479081 or 12479197 Outer Housing?? It sucks i just blew 50$ is bearings and seals.

 

[chucki]

just purchased my 2004 trailblazer a week ago. have a lot to learn it seems. no lights on at switch and service 4wd lite is on. will sniff at later. pulled #8 fuse. 155k miles.

 

[Robbabob]

just purchased my 2004 trailblazer a week ago. have a lot to learn it seems. no lights on at switch and service 4wd lite is on. will sniff at later. pulled #8 fuse. 155k miles.

Do you get a flash of all lights on the switch at engine start? Does anything happen when you turn the switch, like a servo trying to move?

Since it is all of a week old, I assume it started this way at purchase time... and you bought it anyway(?). Did you buy from someone you know, that took care of fluids every (TC) @ 50K and (diffs) @ 100K?

By the way, Welcome to the Nation!

 

[chucki]

no was a dummy and the wife said I like it, so. lights flash. nothing happens when turn switch and are no lights on on the switch.