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4X4 problem 06 2.8 z85

5172 Views 32 Replies 10 Participants Last post by  muccione
4x4 worked perfect last month. now when i hit 4hi or 4lo i hear what i think is the actuator engaging the front diff but there is no power to the front wheels. and the light blinks continuously in 4hi or 4lo but will go back to 2hi no problem. tried changing it in neutral, park, while rolling, in reverse, nothing helps. can anyone help me out? i wanna try out my new tires and winter is fast approaching! thanks!
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i know a member here is fighting that same problem.. @Dorgie
any other input? easy things i can test?
Try putting your truck in neutral, brake applied. Press and hold 4hi till you hear the 4wd servos engage.
just tried that. nothing different happened. you better help me figure it out! i'm getting one of those PTBs when its fixed!
Hey man, sounds like your issues is very similar to mine however if you can here your front actuator engaging you have made it beyond me. In this order the signal transfer from dash control to the tccm under your seat then to the encotor motor on the transfer case once that shifts over your 2-4control sensor will open then send signal to the front actuator.

Now if you can here a noise underneath and it sounds like it's ratcheting like back and forward then you could have a broken shift fork in the transfer case or a potentially bad sensor. I would crawl under the truck and remover the encotor motor off the transfer case 3 15mm bolts I believe once that is off try to shift the truck to 4 hi now if the spline on it rotates a full rotation then the potential of it being a transfer case issue is higher. If you have any further questions or anything I can try to help you with please Let me know
i'll be climbing under it next weekend. i'll know more then. thanks for the tip i'll keep u posted.
Sounds good man let me know what you turn up
So whatcha know?
GM tech was like "oh its just the actuator" so i replaced it and it changed nothing. I love pissing away money i dont have
Well did you try to diagnose the issue on your own?
If you can post some details about what you have tried I'll try to to walk you through maybe even get a vid of your issue
The actuator isnt engaging when it should. I can force it to engage by turning ignition on, pressing 4hi, turning ignigtion off, and then turning ignition back on again. Dont ask how or why but thats what if does. 4hi light still blinks tho. Havent tested to see if 4x4 actualy works with this meathod but inassume it does. In other news my drivers side window quit working WHEN IT WAS DOWN and i lost my power locks. Other three windows work fine. How are scrap prices?
Pull the mother board out for the drivers side control and warm it up common issue. There has to be a connection issue somewhere are you having a service 4x4 in your dic
Have you tried the procedure outlined on page 2-27 in the manual? It sounds kinda bizarre, but they list it when 4X4 Hi won't engage (at least in the manual for my 2005). If you don't have a manual check this thread (post #7, third picture):

Might narrow down your trouble shooting steps a bit, or it might not be of any use to you at all. If I didn't see this in the manual and someone tried to tell me to do this I'd be dubious it was real, lol. What's next, sacrificing a goat?
Warm the board up? Like in an oven? Lol. I got the 4x4 working by turning ignition off and then back on after hitting 4hi. Pain in the ass but its ok for now. No dash lights and those methods in manual did nothing.
With a blow dryer and wicked that you got 4x4 on working wish mine was that simple
yea i'm glad i can make it work if i need it. wish it would work on the fly tho...
Good to here u got your 4wheel fixed. Kinda. N on the bright side u have a back up 4x4 actuator lol
My truck is in the shop right now 08 crew-cab Z71
will not go into hi,low,or neutral everything just flashes till i press the 2hi button it wont even go back to 2hi lit i have to manual change it. To it to the deal yesterday they said they will have to confirm on Monday but they think its the switch on the dash causing the issue they will need to order it so i should have it back by Wednesday . If its just that with and oil change its going to cost me about 400 hope that is all that it is. figured i share may point someone in the right direction.

update just got the truck back today and it was the switch on the dash they has to replace it twice since the first one they put in was bad.
330 bill
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