Unfixable 4wd!!!

catphe10 · February 11, 2019

hello all,

I am sure this issue has been beat to death multiple times, but I cant find the answer.

I have a 2005 Silverado 1500 z71, I have had this issue for about 2 years now. the issue being that no matter what part I replace my 4wd wont reliably work.

here is a list of what parts have been replaced.

Drivers side wheel hub- twice

Passenger Side wheel hub- three times

Diff. actuator- twice

4 button switch on dash- once

TCCM- once

Transfer case motor- once

So what is happening is, the dash will read service 4wd, i have taken it in to a shop where they have been replacing the parts, and i have come to the conclusion they are just throwing parts at it to find a fix. Every time they would replace a part it will work about 2-3 days but then give me the same service 4wd message. if i push one of the 3 4wd buttons on the switch the light will blink for a while then stop and it seems like it doesn't shift into 4wd. But i have crawled under the truck while someone else selects a 4wd button, I can hear and feel the transfer case changing into to 4wd mode. but the front diff actuator does not engage. I have checked and cleaned the ground wire under the drivers door twice but that doesn't seem to help. I am done throwing money at the shop to fix it, so this is my last resort.

any help or ideas is greatly appreciated,

Thank you,

dwntwnbrwn1985 · February 11, 2019

Okay, this topic has been haunting me as well for the last 2 months as well and if it weren't you, it would be me asking. I have a 2003 1500 and I would be curious and eager for the replies. Dunno if this might be able to help, but i will be doing this myself today to rescue my rig from the newly fallen snow in my area. At the front diff. actuator connector (plug), check with a multimeter to see if there is 12v is going through that connector. I ended up purchasing a new front diff. that came from a similar year Tahoe, slapped it in, just to find out while draining that there was a significant metal buildup on the drain plug and had me worried. Swapped axle plates, then yesterday the actuator. It was worthwhile since it would buy me time to learn and research how to rebuild the original. Next was going to see if i messed the wires on that plug since i cant hear the actuator engage either. If that doesn't work, i thought about somehow manually engaging the actuator in a lock position since really that actuator only moves an inch or so to depress that spring on the inside of the diff. to lock it. I dunno if that will work but I'm out of options too and more snow to come!

Silverado23 · April 12, 2019

On 2/11/2019 at 9:59 AM, catphe10 said:

hello all,

I am sure this issue has been beat to death multiple times, but I cant find the answer.

I have a 2005 Silverado 1500 z71, I have had this issue for about 2 years now. the issue being that no matter what part I replace my 4wd wont reliably work.

here is a list of what parts have been replaced.

Drivers side wheel hub- twice

Passenger Side wheel hub- three times

Diff. actuator- twice

4 button switch on dash- once

TCCM- once

Transfer case motor- once

So what is happening is, the dash will read service 4wd, i have taken it in to a shop where they have been replacing the parts, and i have come to the conclusion they are just throwing parts at it to find a fix. Every time they would replace a part it will work about 2-3 days but then give me the same service 4wd message. if i push one of the 3 4wd buttons on the switch the light will blink for a while then stop and it seems like it doesn't shift into 4wd. But i have crawled under the truck while someone else selects a 4wd button, I can hear and feel the transfer case changing into to 4wd mode. but the front diff actuator does not engage. I have checked and cleaned the ground wire under the drivers door twice but that doesn't seem to help. I am done throwing money at the shop to fix it, so this is my last resort.

any help or ideas is greatly appreciated,

Thank you,

They’re trying to replace my tcm as well which will run 950-1000 I don’t have the money for that and I haven’t had any indications for a bad tcm any updates