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Four-wheel drive will not engage?

Tiny
AJONES6574
  • MEMBER
  • 1999 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 230,000 MILES
My four-wheel drive will not engage. The transfer case does not lock in and the front axle actuator does not lock in. The ATC fuse is good and so is the 4 x 4 fuse. I have already replaced the switch twice, because I have known new parts to be no good at times. The indicator lights do not come on at all, even for two wheel drive or neutral and I have no service 4 x 4 light coming on on the dash either. I have cleaned the ground on the frame underneath the driver's door and the ground from the firewall to the engine block. I am beginning to think the module itself is bad, but I would prefer not to just throw expensive parts at this.
I would even settle for a way to rig up four-wheel drive high with toggle switches if it were possible. Can anybody help?
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Thursday, January 17th, 2019 AT 9:48 PM

57 Replies

Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I'm Danny.

Have you tested the front differential actuator? That has been a huge problem for this. I've attached a picture below show on the front differential where it's located. Hope this helps and thanks for using 2CarPros.
Danny-
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Friday, January 18th, 2019 AT 3:18 AM
Tiny
AJONES6574
  • MEMBER
  • 5 POSTS
I have not, however would the actuator not functioning cause the indicator lights to not light up at all? The transfer case does not even try to engage, it does not click a relay or make the normal sounds it would when trying to engage. I will test it this evening and get back to you. How would you suggest I test it?
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Friday, January 18th, 2019 AT 8:09 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Hello,

Can we test for power at fuse ITC. IG1 and 4WD. Here is a guide to help us see and the fuse locations below along with the wiring diagrams so you can see how the system works. Also here is the encoder location.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.
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Monday, January 21st, 2019 AT 11:38 AM
Tiny
AJONES6574
  • MEMBER
  • 5 POSTS
Using your diagrams I found that I did not have power to the orange wire on the plug with the encoder motor control wires when I Supply that wire with power I got it to shift out of 2 wheel drive into 4 wheel drive however now it is stuck in 4-wheel drive high or automatic four-wheel drive and will not shift back out and now my service 4X4 light is on
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Monday, January 28th, 2019 AT 5:56 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Do you have power at the ATC fuse? 20 amp.
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Tuesday, January 29th, 2019 AT 11:29 AM
Tiny
AJONES6574
  • MEMBER
  • 5 POSTS
Yes, I had power there before but it was not making it to the module. However, now when I go to shift it I can hear the encoder motor making noise but it does not shift out of 4x4.
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Tuesday, January 29th, 2019 AT 12:00 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
I would remove the encoder and then with it our move the switch and watch it work to make sure it is working properly. They can make noise but be weak which sounds like what it happening. Can you please shoot a quick video with your phone so we can hear the noise? That would be great. You can upload it here with your response.
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Wednesday, January 30th, 2019 AT 9:51 AM
Tiny
AJONES6574
  • MEMBER
  • 5 POSTS
I will gladly get a video of the noise for you once it is above sub-zero temperatures, but that is what I assumed as well because it did shift into 4x4 this wouldn't be the first time I had an encoder motor go bad. However, I had always had indicator lights before so I do feel as though I have it figured out. I would like to thank you very much for your help.
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Thursday, January 31st, 2019 AT 5:03 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Nice work, we are here to help, please use 2CarPros anytime.
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Thursday, January 31st, 2019 AT 10:19 AM
Tiny
CARHAULJOHN
  • MEMBER
  • 1 POST
  • 1999 CHEVROLET SILVERADO
I recently purchased a '99 chev silverado, push button 4x4, auto, extended cab, Z71, 350, 104k miles. The truck sat for a year or so before I bought it. Before I purchased the vehicle I engaged and operated the 4x4 and it worked properly. Couple days after I purchased the truck the message center in the gauge cluster put up a message telling me to "service 4wd". When I push the buttons to activated the 4x4 nothing happens. No sound, no changing of the indicator lights, 4x4 does not engage at all. Any help would be appreciated, thx. John in Indy
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Saturday, February 2nd, 2019 AT 11:59 AM (Merged)
Tiny
NICKYD01
  • MEMBER
  • 9 POSTS
Start out by checking your fuse it is a 15 amp in the fuse panel located on left side of dash board. If problem persists then you need to bring to a repair shop to have a diagnostics machine plugged in to tell you where the problem may lie. Many Trans. Shops dont charge for diagnosis.
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Saturday, February 2nd, 2019 AT 11:59 AM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
I had this problem with my truck, I replaced the control switch and it fixed everything, let me know please
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Saturday, February 2nd, 2019 AT 11:59 AM (Merged)
Tiny
YAMAHAWHO
  • MEMBER
  • 2 POSTS
  • 1999 CHEVROLET SILVERADO
  • V8
  • 4WD
  • MANUAL
  • 167,000 MILES
I have just purchased the truck fornt actuator was broke off. Replaced it but 4x4 still dont engage. Dont even make a peep. Theguy I bought it off of says he has the sensor on oneof the wheel bearings unplugged ( forgot to plug it in when replaced )could that be the issue or is there something else im missing. Any help would be great
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Saturday, February 2nd, 2019 AT 11:59 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Yes that could be the problem. WIthout it attached, the front differential won't engage.
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Saturday, February 2nd, 2019 AT 11:59 AM (Merged)
Tiny
YAMAHAWHO
  • MEMBER
  • 2 POSTS
I tried to fix it yesterday the abs light went out on the dash but still no 4x4. I used a actuator out of on on demand truck and mine being a manual is stick. Is there a difference. I can unplug the actuator and plug it back and here the motor turn but no engage. Let me know please. I
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Saturday, February 2nd, 2019 AT 11:59 AM (Merged)
Tiny
CCHRISTESEN
  • MEMBER
  • 1 POST
  • 1999 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 223,000 MILES
Truck drives fine in 2 wheel drive. I noticed that the lights on the buttons for selecting 2 wheel or 4 wheel were not lit. I tried the buttons and nothing happened. The 4x4 did not engage. I checked the fuse and it was ok. What could the problem be?

Thanks

chris
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Saturday, February 2nd, 2019 AT 11:59 AM (Merged)
Tiny
99 6.0L
  • MEMBER
  • 3 POSTS
You might have to replace the switch in the dash. There are two electronic switches, one in the dash and one on the transfer case. Mine got stuck in four wheel drive because the transfer case switch went bad, but if the lights went out on the buttons it sounds like it may be the dash switch.
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Saturday, February 2nd, 2019 AT 11:59 AM (Merged)
Tiny
DEB36GORDON
  • MEMBER
  • 1 POST
  • 1999 CHEVROLET SILVERADO
  • 220,000 MILES
Will not go into four wheel drive.
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Saturday, February 2nd, 2019 AT 12:00 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Check to see if there is power to the actuator on the transfer case. If there is, check the actuator for operation.
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Saturday, February 2nd, 2019 AT 12:00 PM (Merged)
Tiny
EINE
  • MEMBER
  • 1 POST
  • 1999 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 93,000 MILES
The truck have push button 4 wheel drive and the light come on says 4 wheel service? 4 wheel drive dont work when the light comes on?
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Saturday, February 2nd, 2019 AT 12:00 PM (Merged)

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