Four-wheel drive will not engage?

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-

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?

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.

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

Do you have power at the ATC fuse? 20 amp.

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.

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.

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.

Nice work, we are here to help, please use 2CarPros anytime.

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

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.

I had this problem with my truck, I replaced the control switch and it fixed everything, let me know please

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

Yes that could be the problem. WIthout it attached, the front differential won't engage.

[quote:510fed1fde="Jacobandnickolas"]Yes that could be the problem. WIthout it attached, the front differential won't engage.[/quote:510fed1fde]
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

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

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.

will not go into four wheel drive.

Check to see if there is power to the actuator on the transfer case. If there is, check the actuator for operation.

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?

have it scanned for codes, then post the codes

4 wheel drive stopped working when i drove over a snow drift. the light does not work the fuze is okay

Hi:
Check under the truck for disconnected or damaged vacuum lines or wiring to the actuator.

Let me know what you find.

Joe

thanks for the reply. it was the atc fuse

When I engage the 4x4 unit, as long as I drive the truck straight, there is no problem, however, when I make a turn, 45 degrees or more, the truck makes a clunking (metal to metal) sound from the front unit...
Can someone please inform me as to what may be the problem? I was told that it may be the CV joints needing replacement, but how would I know this?

To check my CV joints I've always first grabbed the shaft and tried to shake it. I shouldn't feel any play. Then I've raised the front end and again grabbed the shaft and shook it. still should not feel any play. after checking that way I'll grab and hold the shaft with the front end still up off the ground and then tried to move the tire clockwise and counter clock wise just a small amount. When I move the weel the shaft should also try to turn at the same time. A delay means play (ware). I'd also do this with the wheels turned when the joint is being used the most. If in a straight line your not hearing it though even while applying and taking away torque I wouldn't think the problem would be there but since its easy to check would definatly do so just cause I'm there. With it only doing it in a turn sounds like a planetary problem to me. The planetary gear in the diff allows one wheel to spin faster than the other in a turn. In say a right turn the right wheel needs to travel less distance than the left wheel. The left wheel will have to turn faster than the right to catch up. The planetary gears allow this. You can check them for noise by putting the truck in 4 wheel drive and lifting only one side. Put your transfer case in nuetral. leave the key on so the solenoid stays locked but don't run engine. Now spin the tire that is in the air by hand. it should spin without binding. Some drag will be there because of the brake caliper but you should not feel like a catch and release type binding feeling while spinning the tire. You should also be seeing the drive shaft from the transfer case to the front diff turning. If not then that wheel is not connecting inside the diff. Witch could mean bad shaft, bad shaft splines, or stripping gears. When doing any of these checks with the front end lifted try to block the front end up off the ground at the lower control arms. This helps to keep all the drive line there closer to its loaded state like it would be going down the road. Hope this helps.

i put the truck in 4 wheel drive and moved it about 5 feet then the 4 wheel drive lights went out and the 4 weel drive quit i changed the 1 4x4 fuse i found but still wont work would you know what it could be

About the only thing you could try right now, is to remove the switch in the dash, check connections, corrosion, etc. Short of that you are going to need access to a scan tool to retrive codes from the transfer case control module.

alright I am completely lost here I have the push button 4 wheel drive and I also have auto4 we replaced trans case module front actu. and trans motor and I still dont have 4 wheel drive we scanned it and come up with shift lock solenoid and determined it was a broken tan wire and it still dont work frnt act. works but transfer case motor doesent it brand new when u ground tan wire it clicks but doesnt move please help

we also replaced switch and yes I checked the fuses

My truck has two wheel drive , four hi, four low light. the two wheel drive light stays lit up. I push the buttons and no click or anything. No four wheel drive lights work. Has a new switch.

check to see if encoder motor on t case is getting power and working that is one of the major problems like yours . if that is okay then have auto parts scan for codes as it may be something else.

1999 Chevy Silverado 6 cyl Four Wheel Drive Automatic

Hi,

My dad has a 1999 Chevy Silverado. He got it stuck in the snow and had it in "auto" 4 wheel drive. He rocked it back and forth to get it out and eventually burned out the 4 wheel drive. My question is what would be the most likely to have burned out? What kind of a check list should I use when buying him parts?

Thanks for your help.

probably the transfer case,check the fluid it's probably black.plus could have burned the clutches in the transfer case.check the trans fluid too,see if it burnt.spinning the wheels for along time in the snow overheats the trasfer case and possibly the trans.this will be a long list.start there.

On my Silverado the transfer case has a motor on it, the 4x4 selector inside the vehicle is push button with auto 4x4. When I am in 2 wheel drive is the front drive shaft supposed to spin ??? Right now when I am in 2 wheel drive it is spinning. but the front CV'S are NOT engaged.

How do I dis-engage the transfer case ???

How do I know if the transfer case motor or switch is bad ???

When your wheels turn your drive shaft and cv axles will move. When you put it in 4 wheel drive and it doesnt engage its probaly the shift motor. You should be able to hear it engage.

-hope this helps

Bought used truck a couple months back and when I put it in 4x4 hi or 4lo it seems tight and back wheels spin slightly. It will stop on its own while in drive or reverse when at low speeds like brakes are engaging. ABS light is on and recently found both e brake cable on rear wheels is cut. No sounds like grinding from transfer case and goes in and out of 4x4 fine but something is definitely tight. Was going to switch transfer case but have seen some stuff about wheel sensors and actuator motor also.

Hi,

Do you mean it feels tight when it is in 4wd only? Are all the tire sizes the same? Also, if you are on a surface where you have good traction, it will cause a binding.

As far as the lights you mentioned, that can be related to wheel speed sensors.

Let me know about the 4wd issue.

Joe

Well I figured out the problem. While replacing the rear brakes I found that I have a rear differential out of a older model Chevrolet on a 2000 Silverado. I wondered why my truck kept pulling up disk brakes on the rear on computer at the parts store when I clearly have drum brakes currently. Also why both e brake cables were cut. The gear ratio is wrong and was causing the front and back tires basically to work against each other. Hopefully didn't cause any other issues. So far no crazy sound from T case. I found one at a used parts place and matched the numbers in the glove box for gear ratio.

That will certainly do it. Are you able to get the correct one? As you already know, the front and rear have to be the same.

Let me know if you need pics, directions, or help in any way.

Joe