# HELP !! No 4X4 in my Avy !!!



## Superior L & L (Oct 6, 2006)

I was plowing earlier this week and I lost my 4x4 in my 2004 1500 Avalanche. (i know i should not plow with 1500). I checked both the electric engage motors and they are activating but no 4x4. The weird thing is it will work (with some clinking) in 4 low but not 4 high. Our automotive handy man thought it could be electrical since it has 4 low but we are stumped.

Also last year we had some noise in the front diff. 

Please help me it sucks plowing in 2x4 or even worse the back up truck!


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## fyerfytr (Aug 24, 2008)

Superior L & L;660390 said:


> I was plowing earlier this week and I lost my 4x4 in my 2004 1500 Avalanche. (i know i should not plow with 1500). I checked both the electric engage motors and they are activating but no 4x4. The weird thing is it will work (with some clinking) in 4 low but not 4 high. Our automotive handy man thought it could be electrical since it has 4 low but we are stumped.
> 
> Also last year we had some noise in the front diff.
> 
> Please help me it sucks plowing in 2x4 or even worse the back up truck!


Does the 4x4 indicator light up either in 4lo or 4hi?


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## Superior L & L (Oct 6, 2006)

Yep in the cab the light lights up for 4 high and 4 low


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## fyerfytr (Aug 24, 2008)

Superior L & L;660625 said:


> Yep in the cab the light lights up for 4 high and 4 low


You might want to check the sending units on the transfer case. After replacing my transfer case with a rebuilt one, it would only work in 4lo. After replacing the sending units on the transfer case both 4hi and 4lo worked so it's worth looking into.


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## 2COR517 (Oct 23, 2008)

Could be the shift fork in the front axle. Ours went in our Trailblazer. It was aluminum. Did you pull the front axle actuator to confirm it is working?


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## fyerfytr (Aug 24, 2008)

2COR517;660785 said:


> Could be the shift fork in the front axle. Ours went in our Trailblazer. It was aluminum. Did you pull the front axle actuator to confirm it is working?


Thats the other thing I was thinking was the shift fork but I believe it's in the transfer case.


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## MLLC (Jun 14, 2006)

on my old 1500 it was the encoder motor for the t-case. but mine had autotrac 4x4


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## 2COR517 (Oct 23, 2008)

There's a shift fork in the front axle to engage the passenger side shaft.


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## Superior L & L (Oct 6, 2006)

Sending unit may be the ticket.


Any thoughts b & b


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## NBI Lawn (Oct 15, 2007)

Superior L & L;661580 said:


> Sending unit may be the ticket.
> 
> Any thoughts b & b


In my Tahoe the front actuator went bad, the 4x4 light would just flash though. I got under the truck, hit it a few times lightly with a hammer and it worked untill I sold it 

I believe I just saw them in a summit catalog for like $80


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## B&B (Nov 4, 2006)

Does it work in the "auto" position? In other words can you feel the front tires pulling if you launch it hard while in the auto position?

And your positive they pull in 4 low as well? Or your simply stating that it works in 4 low because the T-case is going into low range?


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## Superior L & L (Oct 6, 2006)

We put it up on jack stands and in 4 high the front wheels did not turn when engaged but in 4 low the front wheels would turn


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## Superior L & L (Oct 6, 2006)

NBI Lawn;661635 said:


> In my Tahoe the front actuator went bad, the 4x4 light would just flash though. I got under the truck, hit it a few times lightly with a hammer and it worked untill I sold it
> 
> I believe I just saw them in a summit catalog for like $80


I replaced the actuator motor last year also :crying:


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## B&B (Nov 4, 2006)

Superior L & L;662501 said:


> We put it up on jack stands and in 4 high the front wheels did not turn when engaged but in 4 low the front wheels would turn


What about the front drive shaft? Did it turn in 4 Hi with it in gear and running?

The actuators can make noise and sound like they're engaging but not actually do so. But in your case if it works in low, it should work in Hi as well so I wouldn't suspect the actuator. So I'd be looking for a switch or encoder motor issue first.


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## ght1098 (Jan 31, 2005)

Have you been plowing in 4hi or auto? Might have ruined the clutches in the transfer case.


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## Superior L & L (Oct 6, 2006)

ght1098;662566 said:


> Have you been plowing in 4hi or auto? Might have ruined the clutches in the transfer case.


I plow in 4 hi


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## Superior L & L (Oct 6, 2006)

B&B;662510 said:


> What about the front drive shaft? Did it turn in 4 Hi with it in gear and running?
> 
> The actuators can make noise and sound like they're engaging but not actually do so. But in your case if it works in low, it should work in Hi as well so I wouldn't suspect the actuator. So I'd be looking for a switch or encoder motor issue first.


Yep the drive shaft does turn in 4 hi.


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## B&B (Nov 4, 2006)

Superior L & L;662824 said:


> Yep the drive shaft does turn in 4 hi.


Then I'd be likely to suspect a 4x4 switch failure and not a T-case, encoder motor, or axle actuator.


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## 2COR517 (Oct 23, 2008)

I tried to post this morning but my DSL died. Anyhow....
You said Lo Range works, and your front driveshaft is turning in 4 HI. I presume you meant the driveshaft is turning on it's own when the truck was up on jackstands and in gear with the engine running.. I would still say your problem is in the front axle. When the axle shift fork went in our Trailblazer, the symptoms were very similiar to what you are describing. Sometimes if felt like it would work for a bit, then not. And Lo Range still worked. Also the dash would light up correctly. 
You said the front driveshaft turns in 4 HI. If the xfrer case is in 4HI (with the vehicle not moving) you should not be able to turn the front driveshaft by hand at all. 

Try this test with at least one front tire off the ground. You don't need the engine running, just the key on. Try spinning the front shaft in all Xfer case positions. It should spin easy in 2 HI. No spin in 4 HI or 4 LO. 4 Auto it may spin, with some resistance. If this seems right, I would confirm operation of the front axle shift motor. It should be easy to get off and confirm operation. Pull it off and change from 2 Hi to any other position. You should see the actuator extend, then retract for 2 HI. Also, the front axle sensor is in the actuator. So if the actuator works, the truck thinks you are in 4WD. 
If all of these things work properly, you very likely have a broken axle shift fork. Or something else like a shaft or differential component in the front axle is broken. Replacing the fork will probably require removing the pass side CV shaft tearing down the pass side of the axle. You could probably pull the diff cover and confirm the pass side axle is not connected to the diff gears before tackling that.


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## mikeauto1 (Nov 27, 2008)

*no 4 wheel drive*

i would put a scanner on the vehicle to seee if the any code in computer anywhere. if tyou have a bad encoder motor it would trip a code. then there is a mode in the scanner where you can command the transfer case to go through all the functions, try that if you can get a scanner before replacing any more parts.


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## Superior L & L (Oct 6, 2006)

Looks like im going to have a busy Monday thanks for the help, I will keep posted


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## 2COR517 (Oct 23, 2008)

Did you ever figure this out?


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## RamPainting LLC (Nov 9, 2008)

I lost 4x4 last storm on my 1500 PU, turned out the sensor on the electronic hubs was shot, replaced the sensor and was back in business.


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