pacaguy

I pushed the 4wd hi button, the button just flashes. I can hear the pump at the transfer case moving something , but does not engage. I have also pushed the 4 Lo, Lo flashes as well . Also when I push auto 4wd it also just flashes. it goes into 2hi with zero problem. Nor does it ever slip into 4hi or Lo at any time.

I am not getting a " service 4WD " light. Pulling the dash and inspecting the dash module, I find no corrosion , and being that the transfer case module is safe and dry in the back of the dash , I can only assume ( don't say it ) that it is corrosion free as well.

I have used the search engine here, no solution.

Would really like to hear from somebody here before I have to bring to a shop.
Thanks in advance.

Hammr923

I dont know too much about the newer ones but i have a 94 z71 with the stick to shift to 4x4. i first got it and found out it didnt have 4x4. it was an actuator( notorious for going out) that locks the front hubs to make it 4x4. it could be that or the switch that is in the cab, i have heard people having that problem.... also does your transfer case have fluid in it? sounds stupid but mine didnt and i put fluid in it and new actuator and bam 4x4 worked.

pacaguy

You'll love this, barely any fluid in the T case plus whoever worked on it last stupidly poured
ATF in the case. I went to summit racing to get the auto trac II fluid, not bad at 6.69 a qt. Even though it only takes 2.3 quarts , I bought 4 to have an extra quart on the shelf. After I pour it I'm hoping that the sensor will pick up that it has fluid and engage the 4 wheel drive. If not ill go to the auto switch on the dash and replace it, seems to be a common problem. Then if that doesn't clear it up ill go to the actuator . Crossing fingers .

fsxbob

Wondering if you ever got the 4wd working, because I am having the exact same problem on mine. replaced the actuator and re soldered the switch. I can hear it actuate but then it just goes back.

foxdup1

cant get mine to switch out of 2 hi. the buttons dont respond. I miss the four wheel drive. will take to a shop anyone know the cost I am about to incur?

Bow hound

Test the encoder motor on side of transfer case. Also a lot of problems with the switch!'

Bow hound

Transfer case module failure is very slim.

cmetz

I have an automatic 2005 Silverado Z71 with the 5.3L and 4:10 differentials. I believe I am just shy of 140k miles.

Saturday, I was hauling some stuff in the pasture, and since I hardly ever use 4wd, I make an effort to engage it most every time I take it off-road to give it some use. I don't always engage in 4wd low but tried this time and it would not engage. I tried it in both park and neutral and both at a stop and at a slow roll and even after a few restarts of the engine. vehicletreat Each time I tried engaging it, it would make a loud clunk like it was trying to engage only to fail, and then another follow-up clunk like it was trying again. Then the 2wd light would blink a few times and it would go back into 4wd high. So far my online research has been a failure. In most cases, the symptoms involve no apparent attempt to even engage whereas mine seems like it is trying but something is holding it back.

I have had the "service 4wd" alert on the dash before in the past, however, both 4wd low and high engaged and worked just fine so I never took any actions. Currently, after failing to engage, there are no notifications regarding the 4wd. All I have going on right now is CEL for emissions relating to my fuel evap canister and a weird issue where sometimes when I attempt to start it up it will not turn over at all for a few tries and then all of the sudden work.

I hope someone can offer some advice. I really don't have a practical use for 4wd low at the moment but I don't want it to propagate into losing 4wd high either and would like to address it while the repair cost may be cheapest for both peace of mind and resale value.

wade_carder

ever figure out what was wrong?