I can’t believe how well you went through the process. So much better then other. I changed everything before looking at the 4wd ground wire. Cleaned it then worked great

Thanks for taking time out of your day to share your experience! I'll use your techniques to check my Suburban. One thing I'd like to suggest is when reconnecting the wire connectors, add dielectric grease on them. Some of my issues in the past were related to moisture in the connectors under the truck. Thanks again!

Dude I just replaced the actuator and spent forever trying to clean up the old ground and everything just to watch this and tap into the ground wire at the harness and run it to the main engine ground spot under the hood, thanks a ton! Fixed my problem instantly I cant believe I didn't think of this sooner glad i had all the supplies being it 10:30pm😁

I followed every step of your video and finally SOLVED my issue! I had to add my own wire as I had a break somewhere in the ground line just like you did. Thanks for making this video! Wish every video explained the situation and how to resolve it like you have here!

Tough filming with one hand; camera work was a bit rugged but the information was priceless! Thanks for posting.

DUDE I OWE YOU A BEER!!!! I did the same thing and the guy I bought the truck from even changed the transfer case trying to fix it. I replaced everything else and was about to rip the harness out when I seen your post. 5min after locating that 4 pin connector added a ground and BAM!! it's fixed thank you soooo much!

Dude this insanely awesome fix worked for me. Big ass snow storm hitting us in MN tomorrow and you just saved my ass. I sincerely appreciate you sir. Thank you so much!

I had this problem along with the loss of cruise control. Turned out to be the ignition switch. A local tech figured it out for me after I had gone through all of the grounds and fuses etc. Didn't take him long. If you don't have the tools and or diagnostic skills sometimes it pays to take it to someone that does. $100 fix for me. Great video. Pretty cool watching you guys drill down on stuff like this.

Thanks for taking time out of your day to share your experience! Especially how easy it looks with your explanation

This is the best video. Thank you for taking to time to make it. I hate spending money on service that I can do myself. Thank you. Great video.

Thank you for sharing this. It definitely saved me money and time swapping parts and the headache of chasing it around. Wired it up the same way and the 4wd was back to working order.

I watched this video before doing anything. You were absolutely 💯% right.. Got my meter out. Checked all 4 points. Found no ground. I ran a temporary ground wire and tested. Sure enough it worked. So, I ran a new ground wire. No more "Service4wd" ... Awesome. Thank you for your post on this.

God bless you brother, thanks for your patience and generosity by making this video and helping so many of us. Cheers!

Great video on how to fix the 4x4 system and clean and simple plan too. Love where you should the 4x4 grounds are.

Excellent video. Very thorough. Thank you for going through each potential item and also what didn’t work...... it was interesting how things looked back and you tied in different steps, also enjoy the additional detail for people that don’t use the tools often.

Man you are so awesome, I was at such a loss, switched out the selector ordered the actuator (which is now cancelled) and just happened to stumble on your video and as soon as I watched it I knew this is exactly what it was, went to Home Depot bought a multimeter, a pack of vampire connector and sure enough after maybe 30 minutes in the garage, my selector lights are working, service 4wd message is gone, and this encoder sounds like it has so much more power! Thank you so much you helped me out a great deal and I’m sure you’ve saved many asses, hats off if your ever in Oklahoma, beers on me!!

Phenomenal video! You should be teaching this stuff at a college. Could not have been more thorough. Really impressive skills in explaining the process and reasoning behind it. Thank you!

Brother that was a great video. I'm educated in electronics and love auto electronic troubleshooting. Your video will help many people find the failure related to the notorious service 4WD message with your troubleshooting procedures. There is nothing wrong with repair shortcuts like your repair if resources are limited or just need to get up and running quickly. Most will start throwing money and parts at their trucks so thank you for taking the time to share. I've subscribed and will keep an eye open for more videos from you. Take Care. Stephen from North Carolina

Good info 90 percent of the electrical problems can be traced back to lack of ground. Thank you for sharing. Make up a simple jump wire @ 3' long with a clip on both ends to do your ground testing is one of the cheapest and most useful tools you can have. Very good info. Thanks

Thanks for the tips, like you said a thousand dollars later and still no 4x4, it's drove me crazy until now!

Blue wire? Three phase? Haha. Great video bud. Thank you for sharing the knowledge.

Thanks for sharing this! It gives me a great starting point to figure out my 4x4 issue on my Tahoe. 👍

Dude, you rock! I had the same issue on my 2005 SLE, with a Code C0379. I didn't have a power probe (ordered and coming in tomorrow) so I back probed the ground wire at the actuator connector with a paper clip, attached a jumper wire to that with a small needle nose vice grip, and attached the other end of the wire to a random frame bolt with another pair of vice grips. Powered up, hit the 4H button, BAMM! it worked. Hit 2wd and it switched back no problem. I followed the harness from the actuator up under the hood, where it connected to the same style plug as you showed. Spliced into the black wire and ran the wire over to the right side of the brake booster to a firewall stud located between it and the fender. I liked that the wire was a little more discrete in that location. Thanks for taking the time to do the video.

My kind and of guy right there! I’ve been having problems with mine and when it works it works. I know I’m having the same issue. I’m just going to jump to the fix. Reasons why I watch KZfaq before I even take anything apart. Why waste time when someone already has! Thanks for the help!

Thank you, mine started doing this yesterday. I'll try to fix it myself.

Thanks for the advice! I'm sure helps a lot of people

Thanks, I have a low milage 07 duramax that the 4whl drive hasn’t worked in 5 months. It’s horrible in 2wd in the snow and mud. I worked at a shop in my early 20s but its been decades. I was getting super frustrated with it and myself. Your video helped me a lot as far as what to look for and how the system works. All my other trucks were manual trans and manual 4x4 so were easy. With your video and 1/2 of a Sunday I was able to get it working again!👍😀

Same as many others who have seen your video, thanks man. I swapped out the encoder motor and switch. Nothing worked untill I checked the grounds and added a ground wire.

Great video and info!! And I appreciated the comment at the end about losing your favorite wrench, gave me a chuckle. Subscribed!

Gonna have to try this. I tried the motor, the switch, the brain, the ground on frame, front actuator and transfer case speed sensor and nothing has worked. Thank you for posting this.

THANK YOU SIR! i'm about $400 in on this fix so far. So glad I found this video, gonna try these suggestions tomorrow. was about to go get the TC motor but maybe this will save me a few hundred... fingers crossed

Thanks for posting this, my Silverado is doing all of the wonky selector switch stuff as well. About to jump in now.

Hi I have been troubleshooting for some time on my 4WD issues. So I went through the progression of the grounds cleaning first. Then instead of replacing the actuator motor i decided to go after the position sensor within, much cheaper of course. I got the AC Delco on Amazon for $35. So when i disassembled the actuator i noticed that the gears were previously matched marked but low and behold the factory match mark did not line up. I went and installed the gear, not where i found it but to the factory marks. So yes the smoking gun! I reassembled everything and my intermittent service 4WD and the selector switch with the random lights coming and going were gone! That's great unfortunately it still would not shift into 4WD. So next step was the front diff actuator. I pulled it out and gave it power but it didn't budge. So I checked the voltage at the plug and got the 12 volts on the brown wire but got no ground on the black wire - should have read 000 on the ohm meter but only read 1 meaning no ground like the video. I tapped into the ground with a vampire connector right close to the plug instead of chasing it back. I ground down a spot on the frame and ran new wire to the frame and fastened it with a self tapping screw. Tried it again and Viola! the motor turns. Reassembled it all and it works perfect. Thanks so much for the video help and helping the diagnosis, solved both issues for $35.

Thank you. Great info. We have to turn in to detectives with our vehicles.

Actually a very helpful video! Going to try this on my '01 z71 4.8. Got one for you. I lost all drive while shifting through 2 and 4wd. Now when I shift from neutral to park I get a grinding sound. Park doesn't lock the wheels. Someone who knows, will know in a second. Please help me out. I hate to throw parts. Reason I really love this video. You actually show how to diagnose. Thanks man!

Great video. I've been fighting this for months now.

Trying to get my 93 body changed and all this is done with a lever.

Thanks man! You rock! 🤘

Fantastic! I'm going to try this on my 2006 c4500 dump truck. I can hear it working but now I know what else to look for. Thank you so much!!

Thank you for your excellent video! My Yukon XL dropped into 4L from 2H by itself on a highway today lol! Checked every ground on the frame, wires and the 4wd fuses. Wallet and Yukon not ripped apart!👍

thanks for sharing! I'll try running ground wire tmrw. Was wondering if its not to much to ask The blue wire you ran. To which color wire on the clip did you tap into?

Thanks please thumb up and subscribe!!

Awesome video brotha!! Glad I found this video I was about to start changing out unnecessary parts. I followed your instructions but I ran my ground wire underneath the driverside next to the main grounds. Got a clean ground and now my 4x4 is working again!

I have a 2004 Avalanche ...Service 4WD ...same issue.... I am going to try this, I too have been fighting for 2 years... replaced switch, replaced TCCM..... error comes on ocasionally (usually when you need it.) has been working great for months until the Giant pot holes on the interstate jarred the truck to death.... no more 4WD....... I am more than sure it is a Ground wire, you have given me a great place to start...THnx

Seriously, thank you very much. I’ve been changing all kinds of things and running through all kinds of things.

The grounds on this body style are so problematic that there should have been a recall. Thank you for the heads up on this one!

After watching a couple vidoes and in one it said the form said to start with cleaning off ground bolts. All I did was clean the ground bolts with wd40 and toothbrush and it worked . Before that none of the lights for 2wd 4wd lights were alumanating and was getting service 4wd code. All good now. Thank god for youtube 🙏

Man I can't thank you enough for sharing this knowledge. God bless you

i have that problem with a customer sierra. thanks for the tip, hello from Mission Texas

Thank for sharing this video. You explained everything so people can understand it. I just replaced my switch, it didnt work then after driving down the road I tried again and it worked, got home moved a little snow and it quit working again. I thought well I'm gonna check the harness tomorrow. But thank for pointing this out. It helps people out so much. Thank you again. Ron

Great video, one handed dexterity is looking good, I did an o2 recently and had to connecti it one handed, it took a bit but i got it. No to try and fix this ground issue, I have already cleaned the terms under the truck on the frame, so not i will check the front acuater ground. thank you very very much for the video, good good stuff here.

Thank you for the video. I have the same message popping up on my 05 GMC Yukon. I think this video will help me better diagnose what's going on with it. Again, thank you.

Tnx friend, i just got a Avalanche with this problem, i was looking for info on how to fix it, keep t vids coming i just subscribed!

Money saver thanks a lot. Much appreciation for this video man. Didn’t spend a penny thanks to you.

Thanks for actually explaining what to check for, cause I was about to try replacing everything as well!

I did the same exact thing and replaced EVERYTHING! I hope adding a new ground will fix it. I've been at it for 3 straight days. 😤😡 (I got yelled at too 😂) Anyway, thank you for taking the time to share!

Appreciate the video walk through, my 04 z71 just threw the service 4x4, I am going to change out the selector switch anyway as the buttons are pretty beat up/scratched up but will do the steps you showed while I'm changing it out just to be safe as well

So after i took a look at the cables at the shaft and sqeezed them for a bit it worked.. so thank you for saving me alot of money

The best video for 4x4 problems.

Great video and you made it very dummy prof I dread electric stuff but after watching this I feel pretty confident I can figure this out

Thanks so much for this video, I’m just now having problems and I believe you may have saved me a ton of money! I really appreciate you!

On my third switch in a 2005. Thanks for extra troubleshooting though in future

Good video. My has been acting up and quit this morning. Ill try these tips. Thanks.

Great video.Thanks for taking the time. Headed out to check mine and fix the service 4wd.

Thank you for the in-depth troubleshooting. This will save me a lot of time and effort for my service 4 wheel drive on my 06 Sierra

Dude you just got a new subscriber to your channel Thank You for an Amazing video I had checked all my fuses and cleaned the grounds and nothing spent awhile searching online found your video and with in 15 min had it fixed

Thanks for a realistic explanation and video man. It wasn't my problem but it did eliminate everything to the point I did figure it out. Thanks again

Let's make this guy have a lot of views for this bad ass video so he can get some money for all those parts,thanks for the video man...

Hello friend, looking for a solution to my problem with the 4 x 4 service failure on the cluster screen of my 2006 Hummer H2 truck, I have found your video. I really liked his video and way of explaining everything and the most important thing is that he does it selflessly and this is greatly appreciated. Regardless of whether I can fix my bug or not. I have been struggling with my problem for many years and they have not found the fault, they have told me to change some parts but none in particular, therefore I did not want to spend money on parts without knowing 100% which part it was and which one. was the cause of that failure. The only piece that was changed to try as it was not very expensive, was the dashboard button panel, apparently it was solved but soon the same problem reappeared and is the same that happens to your truck. I left this failure as impossible because as up to now the technical inspection service of my country "ITV" had never put me in trouble for this failure because the truth is that my truck was left with that failure until today that I have had to go back to return to the problem of this failure because the technical inspection service of my country "ITV" in "Spain" has negatively failed me this inspection due to this failure. I have to resolve this fault as soon as possible since my truck cannot circulate without this unfavorable inspection documentation. By the way, I have already liked him and subscribed to his channel from my two KZfaq accounts. Thank you very much for all your attention friend. A greeting from Spain.

Good job helping people out.

Awesome how you explained everything so it would make sense really good video

Thank you for info! My 2006 Silverado just started acting up with service 4 WD. This info will help not get ripped off

Thanks for advice. Note the hanging harness has a push clip to hold it up. Im troubleshooting now.

THANK YOU SO MUCH! My 2005 Tahoe is having the “Service 4WD” error message. A yr ago, I replace the dash switch, fine until now. I know the mechanical parts work - it is stuck in 2WD, and I cannot change this, so the error has got to be a faulty ground somewhere. MUCH APPRECIATED!

Dude you rock for fixing your problems better than a wanna supposed to be mechanic.

this is so crazy. I bought new for the first time in my life and I`m 64 years old. I looked for the the cheapest Yukon that I could find. made the deal when I picked it up it had 2 miles on it. nobody drove this truck. it owes me nothing. 345,000 miles on the Original motor & transmission. I did almost the same thing that you did. Switch, shift motor & actuator with no luck. I figured that with all the miles on her that the Transfer case was beat. oh and I even did the ground lines under the side of the drivers side door. I even ran a main ground line from the first connection where the negative side of the Battery goes to. then ran it to the fire wall then ran a main from the fire wall to the frame on the drivers side making sure that I have a good ground. watched your Video and said no way. but I just did exactly like you did and no more blinking light on the switch and no more SERVICE 4X4 on the dash and everything works as it should. I can`t thank you enough for your Knowledge on the way you chased this problem down. I have played with this for a year and a half and I was stuck on a TCCM or a transfer case. until you. I am still in shock but with a smile. Thanks again Bill

Thank you for the video! I will let you know how it turns out.

Ok I see the last comment was 3 years ago, but THANKS. Now I have direction to go. Thanks again.

hope them wires are good looking, i might have to buy a new transfer case for my z71. this video helped alot to see which area might be the problem but still ill check all areas.

I have a 2004 Chevy Avalanche, and been dealing with 4wd issues for almost a year. One shop quoted me $900.00 and said I needed a new Actuator.(lol) The issue I'm having is the lights turn on on the selector switch at start up, but all turn off soon after, I also have service 4wd on the dash. I have replaced the rear actuator motor, 4wd selector switch, tcm, and cleaned up the ground underneath the drivers door but still have the same problem. I will check for true ground at the front actuator as you recommend, and post an update. Thanks for the video!

Really good explanation buddy! Keep up the good work

Winner , Winner, Chicken Dinner!! Nice amount of information, just what I needed to see before I start t-shooting mine! thanks so much

Very nice and thank you so much for your time and information

great video , good steps , im going to check my hummer h2 , thank you very much

Great video very detailed and down to earth. Two thumbs up.

We have a 2004 Chevy Suburban that does the same thing. We bought all new items, like you. Now my husband is going to try and see if it is the ground wire issue. Because sometimes it comes on and goes off when going over bumps.

sounds like you watched the same videos I did and started chasing parts $$$ thanks for posting ! I sub - d

Great explanation. Very useful. Thank you.

Thank you for the video my fuse was blown but still no going into 4wheel drive and service 4wd. So im try the ground thing and if that dont work im going to do the t case motor. 2005 GMC Sierra 1500 crew cab

Fantastic lesson sir thanks

Cannot thank you enough for this video. Big snow storm coming and my 4wd is shot. Tried splicing off the ground and it worked! Great video.

Your video is awesome. Nice explained video.

Brother thanks for this. Came in right on time for me doing maintenance and upgrading for my 03 LS.

Bro mine was a cut power wire but you sent me in the right direction and I got it fixed with solder and tape YAY!!!!

Have a 03 duramax had same iyshue this worked and with a bonus it also cleaned up the injector haze worth a try

Very good diag video. Thank you.

Excellent job! This was Very Helpful 🎉

Dude, youre awesome, Thanks for sharing.

I hope this works on my truck, I’m watching at work

Thanks bud. Helped a bunch!