4 wheel drive low

Tiny
CHILLWILLATX
  • MEMBER
  • 2006 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 80,000 MILES
When engaging the 4 wheel low there are loud poping noises. This noise sounds more like a clanking of objects together. Imagine that you are knocking on a piece metal, this is the sound that occures. The noise is repeditive and occurs about 3 times before the system engagues back into the previous gear selected. If you were in 4WH then you go back into 4WH, and same for 2WH. I have tried to engauge 4WL from 4WH & 2WH both; in neutral, in gear moving slowly, & in reverse. I have not owned a electronic 4 wheel transfer case before and need some advise. I do not believe the switch is bad because you can hear the soleniod operating on all 3 selections of gears & all the lights do work on the dash gauge selection. 4 wheel high works properly and the truck engauges in and out of 2WH AND 4WH fine. What could the problem be? A soleniod, an actuator, Ive heard of an encoder moder?, Or did I get a bad transfer case?
Monday, February 1st, 2010 AT 2:31 PM

25 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,560 POSTS
Have you checked to make sure the front u-joints are good? Also, when shifting to 4lo, many times it is common to hear a clunk. You are changing the gears in the transfer case and they can make noise. That can also happen from lo to high.

Let me know about the u-joints. IF they seem good, you may want to have the 4wd actuator on the transfer case checked. It may be hanging up and slow to shift.

Joe
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Sunday, January 27th, 2019 AT 8:22 AM
Tiny
APSK7429
  • MEMBER
  • 1 POST
  • 2006 CHEVROLET SILVERADO
Transmission problem
2006 Chevy Silverado V8 Four Wheel Drive Automatic

My 06 will not shift into 4 Lo. I can hear the hubs try to lock in but then they disengage and it shifts back to 2 Hi. It is push button 4WD. Im not sure. Could it be a sensor?
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Best bet would be to have the drivetrain scanned for any codes that may be stored in the PCM's memory. If a solenoid or the such failed it should record the failure. Get back with results of the scan
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
SAWGRE
  • MEMBER
  • 1 POST
  • 2002 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
My transfer case shifts into 4 Lo but my front axle doesn't engage. Yet in 4 Hi it does. My pickup has the Auto 4 wheel drive system. I think its electrical in nature so I would like some trouble shooting advise or maybe a wiring diagram of the 4x4 system.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
CRZYDRVR
  • MEMBER
  • 432 POSTS
It is most likley that the 4x4 switch has gone bad internally. I've had to replace several of them including on my own truck.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
BDWLF2
  • MEMBER
  • 3 POSTS
  • 2000 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
My Silveraldo's Trans went out. I took the trans and transfercase out of a 2002 that I had and put it into my 2000. 4WD worked great for about 3hrs. I can hear and feel the 4WD engage but doesn't seem to send power to the front axle. I replaced to the actuator in the front axle and still no 4WD. I put in 4LOW and the low "gear" kicks in, but still not the front axle. I can "hear" the actuator moving if underneath the truck. If I jack the front off the ground and move the tires, I can feel the front axle move the driveshaft and dis-engage when put in 2HI. I am completely stumped. I can hear and feel 4WD kick in and out with motor of and in the air, what could be the problem?
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,600 POSTS
The best thing to do is to check to see ifyour front axle is getting the power at the actuator and if it is good power not weak power or low voltage. These actuators can go bad as well, but can be fixed if they are taken apar very carefully and then when put back together use silicone on the ends to keep them from getting crap in them as that's what happens and they no longer work right. It may be just the actuator is bad as we don't know what t case you have. It could also be a ground problem or connections that are bad. Aka not sending enough voltage
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
BDWLF2
  • MEMBER
  • 3 POSTS
I have already replaced the front axle actuator. With the front wheels off the ground I can feel the resistance of it engaging when I spin wheel by hand. I can feel is disengage when I go back to 2HI.

I when into a gravel lot in 4HI and 4LOW and only rear wheels spin. It's like the transfer case isn't sending power to the front.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
BDWLF2
  • MEMBER
  • 3 POSTS
I can also "feel" the transfer case shift into 2HI, 4HI, & 4LOW and hear the motor engage it. But no power to the front. The rear axle responds to HI and LOW settings but not the front.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,600 POSTS
Not seeing your setup the question that comes to mind is did you use the original actuator off the 200 truck or the 2002? I think the problem may be that the 2002 has a module for the t-case and the i'm not sure if the 2000 does or not. It will be under the dash on the passenger side I think. It could also be the wiring ging to the newer trans may be different from the one you took off. I'll have to investigate this further wiring issue wise to see if that is where your problem really lies. Hopefully you have checked th estuff like fuses and relays as they may have gone bad as well. Those should be in the underhood electrical center if they have one which i'm sure there are.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
ALLEN
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
Stuck in 4 lo 2000 will not come out, when I push 2 wheel drive buttonthe light does not light up at all 2000 silverado 1500
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,600 POSTS
I looked at teh schematics and most stuff seems ok. But there is a front speed sensor for the front prop shaft and see if that is connected well or the sensor may be damaged. It is on the case where the shaft comes out. It may not be reading that the shaft isn't turning causing your problem. Or the wires are screwed up like a bad connection or were damaged.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,560 POSTS
Check for power to the actuator on the transfer case.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
ODIE0716
  • MEMBER
  • 2 POSTS
  • 2000 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 132,000 MILES
When I push the 4hi button it doesn't stay lit, it just blinks and doesn't engage. When I push 4lo it clunks like its going in but the indicator light keeps blinking and I don't think its going in to 4lo.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
TY ANDERSON
  • MECHANIC
  • 682 POSTS
We see this often.
Typically what happens is usually the encoder motor that shifts gears inside the transfer case is faulty. But this is just what I've seen in the past.

A few susgestions would be to get all four wheels off the ground and support on jack stands. Shift the transfer case and see if all four wheels spin.

Unplug the electrical connector to the transfer case shift motor and look for any corroded terminals in the connector.

If your mechanically inclined. You could remove the transfer case shift motor and move the shift fork on the transfer case to see if the issue is the transfer case itself. Do this with the wheels off the ground because you may need to move the wheels/drive line to allow the shift fork to move.

Try these test/checks and get back to me or if you have any more questions feel free to reply
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
ODIE0716
  • MEMBER
  • 2 POSTS
Thanks Ty. I figured out that the 4lo is working, but it just does not engage in 4hi. So I was wondering if you thought it could be something as simple as the transfer case vacuum switch? I was told that it could be one that one the vacuum lines to the 4hi could be clogged or even broken?
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
TY ANDERSON
  • MECHANIC
  • 682 POSTS
The transfer case control module (computer) controls all aspects of transfer case operation.
When the driver selects one of the transfer case modes a signal it sent to the computer and the computer sends the command to the transfer case encoder motor to shift to the appropriate gear. There are no vacuum lines running to the transfer case. (There is a rubber vent hose so don't confuse it for vacuum) Most modern transfer cases are now all electronically controlled.
Typically the issue is the encoder motor for one reason is it worked more than any other component.
My bet is on the encode motor assembly.
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Thursday, January 2nd, 2020 AT 9:00 PM (Merged)
Tiny
BFORBY1
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET SILVERADO
Drive Train Axles Bearings problem
2000 Chevy Silverado V8 Four Wheel Drive Automatic

Have a 2000 Chevrolet Silverado 2500. The service 4 wheel drive light came on and the lights went out on the buttons on the dash. Took it to the dealer and they hooked it to their computer and they said I needed a transfer case motor. I replaced that and now the lights work. You can hear it switch the transfer case and it even gears it down when you put it in 4 low. When on the rack and you put it in 4 wheel drive the front tires will move but once on the ground the 4 wheel drive doesn't work. Any ideas what may need replaced now? No noise coming from the front differential while driving and it drives fine just no 4 wheel dig.
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Thursday, January 2nd, 2020 AT 9:01 PM (Merged)
Tiny
QUAGMIRE86
  • MECHANIC
  • 98 POSTS
If the 4wheel drive is engaging without a load on it, the solenoid (on the front axle) seems to be engaging. It may be an issue with the shift/shaft fork (attached to front axle solenoid) may be worn enough where it is not pulling the gear far enough in to keep the front axle engaged when there is a load on it. You will need to check for power to the front differential solenoid to be sure its actually getting signal to lock the front diff

See the attachments below to see what wires to test
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Thursday, January 2nd, 2020 AT 9:01 PM (Merged)
Tiny
ASHLEY LYONS
  • MEMBER
  • 3 POSTS
  • 2001 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 305,000 MILES
Getting truck running again it went into 4 Low and will not come back out. It went from 4 Low to high too high no problem before, but now it will not come out of 4 Low. I can hear the encoder motor trying to shift and my front axle actuator moves as it should, but it will not get out of four low.
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Thursday, January 2nd, 2020 AT 9:01 PM (Merged)

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