KyleStubbins.com

I have a problem with the 4x4 on my 2002 gmc. sounds like a scraping noise in the front end. Used to clear up by shifting to 4x4 and back to 2wd. Is there a way to check the hubs(sticking) or the cv joints? Where can I find a diagram or explanation of how the GM 4x4 system works?

Thanks

Hi Jeff;

Sorry, I'm not going to be much help with your questions... I'm not a mechanic and can only give you information that I have learned while fixing my own vehicle. Unfortunately, what you describe I have not encountered.

As for how the 4x4 system works, what is it you want to know? It's pretty basic actually. The encoder motor engages 4WD within the transfer case which drives the front differential. The drivers side wheel is always engaged at this point and the passengers side wheel is engaged via a vacuum controlled cable (actuator - lunder the battery). There are no "hubs" (so-to-speak), not in the way that you use to see on the older systems where you'd have to lock them.

The only thing I can think of is to get it up on a hoist, put it in 4WD and listen to it. Hopefully, you'll be able to pinpoint where it's coming from.

Good luck!

Kyle

You can ignore/delete my submission from last night. I found out that cable coming through the firewall under the glove box was the antenna cable. I also removed the kick panel to find the amp's power cable butting right up against the TCCM's cables, which got me worried. But I tested everything and, except for the 4LO problem, everything seems to be working OK. I just still have that rubbing/vibration noise. I decided to take it to a local shop. Thanks for all the good info. I bookmarked your site.

Kyle's reply;

Hi Kan;

Hmmmm... sounds like you have an interesting one on your hands! Personally, I wouldn't think that running your amp/speaker wires would cause the problem that you describe, but I've seen stranger things happen!

Unfortunately, the only way you're really going to tell if that's the case is to remove the wires and see if it goes away (I know you've taken it to a shop now, so that point really is moot).

Other than that, I would suspect that the rubbing/vibration that just started after your wire routing is coincidental.

I really don't know what to tell you, but if it were me, I'd jack the front end up and check the front end parts (tie rods, ball joints, idler arm, drag link, etc.). I've replaced the drag link, idler arm and upper ball joints on mine, but that was due to a loose front end (drifting) rather than a vibration/rubbing. Basically, I jacked up the front end, grabbed the tires (one at a time) top and bottom and "wiggled" to check for excessive play. Then grabbed them front and back and wiggled again. It's helpful to have a second person to do the wiggling while you get under the vehicle and watch the various parts for movement. If things are tight, everything should move TOGETHER just slightly (depending on how hard you're wiggling the tire). If the movement is seen in one part, but stops at the next, the joint/connection between the two parts is the problem. I'll give you one last tip regarding this... if you take your vehicle in for an oil / lube job MAKE SURE they are actually lubing your vehicle! I took mine in for probably 5 or 6 oil changes before it was noticed that the shop was not lubing my vehicle. I'm pretty sure that was a major factor in the wearing of my front end. Long story short, I do all my own oil changes/lube now and only took it in because of the tires I bought... they were rotated and balanced every 10,000KM for free, so it was worth it for an few extra dollars for the oil change while I was there -- ya just gotta watch 'em like a hawk and make sure they do what they're supposed to be doing.

Good luck with your problem and please let me know how you make out.

Regards;
Kyle

OK; got the Blazer back from the shop. You were RIGHT ON when you said that it was coincidental with having installed an amp. As an FYI for you and your readers: They diagnosed the problem as a bad bearing (driver side, front). They said the reason the vibration went away when turning left was because the weight of the Blazer shifted to the right side. Apparently the bearing assembly also has ABS sensors, so it cost US$230. With labor, an alignment, and an oil change, cost about $500. That was the bad news. The good news is that they fixed it. So, lesson learned: problem caused by newly licensed teenage son. Translation: doesn't care about how fast he goes over railroad tracks, speed bumps, or pot holes ("since it's a 4x4, shouldn't it be able to handle that Dad???")

I will continue to read your excellent blog!! Thanks Kyle!!

Kyle's reply;

Hello again, Kan.

LOL! Teenagers, eh? Well, can't say I haven't been there and done that! :)

Glad you got your problem resolved. Thanks for coming back and letting me know what the problem was, I'm sure it will help someone else out at some point.

I actually think I have to do the same thing... I've just picked up a small vibration in the front end AND had the ABS light come on. Hmmm... a common Blazer problem me thinks.

Regards;
Kyle

Yes my name is kyle and I have a 1999 chevy blazer 4x4 and i have the same tccm problems like everybody else but my only problem is that i need the new 32 pin femal plug and the 4pin female cause my tccm is in working condition. I can't find then plugs and wires anyplace :) i know what are odds there. My second problem is that if my blazer sits for a few days and doesn't get started it doesn't want to start and you have to spray starter fluid in the vac line on the throttle body and also with that when you go to give extra gas for say highway or pulling out infront of a person the blazer falls on it's face. I have replaced the plugs twice, wires twive, coil pack twice, and had oil change and tranny flush(and tested) fuel pressure is good. no servive engine light or service 4x4 either! please help me somebody!

I have a 96 chevy s10 blazer 4x4, my front axle wont engage. I can hear it go in via the transfercase but front tires wont turn. The light comes on so I dont think it is electrical. I did locate the vaccum actuator under the battery but there was no vacc line attached to it. I have no Idea where the source of that vacc comes fron is there any way you can coach me through it or send me a diagram. The actuator itself looked to be in good cond. I just noticed that the nipple on the actuator was open(no hose to it.) I would apreciate any assistance.

Kyle's reply;

Hi Randy;

I am not sure where the vacuum line comes from on a '96 Blazer, but I have only heard of it coming from two places;

1) the vacuum comes off the drivers side manifold and goes to a reservoir (also on the drivers side), then to the vacuum switch (center firewall), then to the actuator (under the battery) -- this is where mine is located. Here's what the vacuum switch looks like --> http://kylestubbins.com/files/blazer_vacuum_switch.jpg

2) the top of the transfer case (I believe that's what one of my posters had said... it was that, or on top of the transmission -- I can't remember exactly, but it shouldn't be too hard to find -- follow the vac lines!

Good Luck!

Kyle

ok sooooo 2000 chevy s-10 4wd zr2,,,,,,
4wd drive would not work nor would lights on dash come on or change from 2hi to 4hi or 4lo. also seem to lost some vacuum in the dash regarding heat and dash vent air. they wont switch from floor heat to dash air.
rewired wires to TCCM. bipassed the corroded harness. had some response. now the lights would come on the dash and i could hear the TCCM "click click" but lights would flash and go back to 2hi. 4wd never did engage.
changed the vacumm thing under the battery and also changed the actuator switch on the transfer case AND changed ALL vacuum lines.
cant find any bad fuses either.
still nothing. any ideas?

Kyle's reply;

Hi Kirt;

Wow -- sounds like you've done everything that I would have suggested. Accordingly, the only thing I can think of at this point that you haven't done would be to change the encoder motor.

I know you've changed all the vacuum lines, etc. -- but have you actually tested for good vacuum?

If you have someone to help (you'll need them in the vehicle to push buttons while you're under it with a volt meter), you could grab the schematics from the first post and test the wires at the encoder motor. Test the main 12V leads to make sure you're getting main power to the motor, then test each of the 5V signal lines to make sure you're getting the signal to change modes at the encoder. If everything is good, odds are your encoder motor is shot.

Oh, BTW, if you haven't read it in one of my posts here, there are fuses UNDER THE HOOD that you might want to check as well.

Good luck and let me know how you make out!

Regards;
Kyle

I found the problem...it was the U-joint on the front drive shaft.

Thanks for the info on the 4x4 system.

Kyle's reply;

Thanks for the update, Jeff -- glad to see you got your problem solved!

Regards;
Kyle

When I backed out of the drive way the right front wheel made a sound like metal hitting metal, very loud and ruff. I thought the wheel was going to fall off. I drove it just a little bit and every right turn it would make sounds and you could feel it in the ride. My son noramlly drives this car and it has been doing this for some time, but sometimes stops for weeks at a time.????? any ideas? thanks Michelle

Kyle's reply;

Hi Michelle;

Assuming the problem IS coming from the passenger side front wheel (sounds can be very deceiving) it could be a number of things. It's difficult to say if the sound goes away for weeks at a time, as well as not knowing what happened prior to the noise -- for example, was the vehicle put in 4 wheel drive and then the noise started?

If I had to guess though, I'd say wheel bearings, a sticking caliper, CV joints or maybe a front U joint as our last poster, Jeff, reported.

It could also be something as major as the transfer case (mine made a really loud and rough bang when I had problems with the shifting from 2HI to 4HI -- sounded like I ran over a garbage can). The thing with that though is that the sound didn't go away.

Either way, I'd have it looked at ASAP as front end problems can be quite dangerous (and if it's a transfer case problem you don't want to destroy it by letting it go).

Good luck!

Kyle

Ok so my 2001 Blazer has been having this problem of the ABS and Parking brake light coming on normally when i hit a bump...also it seems as if i have to change the brakes on a regular basis considering little to no use...im in the service and therefore drive the vehicle maybe 2 times a year for a period of 2 weeks and everytime i come home it seems im changing breaks because they have warped or are just falling apart...my mother uses the vehicle in the winter time and its hard to say how she drives it since im not around (id assume she is careful) anyways im currently in afghanistan and the newest news is that she smelt brakes burning when she last drove the vehicle and the dash lights are not turining off as they did b4...she may just be being paranoid in regard to the smell but im guessing its a bearing or something since last time i drove it b4 changing the brakes it would shutter heavily and veer to the left when i tried to stop...id like some type of input since ill have to fix it next time im home and dont want to get hussled by a mechanic, thnx

Kyle's reply

Hello Guest;

Unfortunately, it's hard to say for sure, the ABS / parking warning light can be a number of things... I'm going through the same thing right now.

Last week I changed both front wheel bearing assemblies as they are all one unit and contain the ABS sensors. This is what "everyone" said is the number one problem... it may be, but it wasn't mine. The lights remain. Unfortunately, I couldn't get it scanned at the time and opted to change the wheel bearings anyway as the vehicle has 270,000KM on it now and the bearings are rated for 128,000KM - 160,000KM -- I figure I got the life span of them. ;)

Anyway, since then I've had the vehicle scanned and found the problem to be the ABS pump/module or simple the connections. I should have written it down, but when it was being discussed with my mechanic, it wasn't an option for fixing at this point (he figures around $1,000... I don't know for sure as I haven't looked to much into it). I don't plan on going any further with it. The lights are on... if it bothers you, I'll put electrical tape over it. ;D

As for the parking warning light... I don't know how much I buy the explanation I got from the mechanic I talked to, but "he said" that the parking warning light will just start coming on after the ABS light has been on for a while. Sounds like he doesn't really know, so tried to BS me.

As for your brake smell, from what I understand when researching doing my brakes is that the calipers are prone to sticking after a brake job. What I would do is drive the vehicle until you smell something and then stop, get out and put your hand on the wheels one at a time... even go as far as sticking your fingers through the spokes and feeling the rotors or whatever you can reach... you'll know if one is extremely hot then this could be your problem.

Hope this helps.

Regards;
Kyle

Hi I have a 98 blazer 4x4 that has had 4x4 issues for quite some time now.....about 2 yrs ago I replaced encoder motor...and the vacume switch on transfercase because it was bad....vacume actuator under battery was in good shape being the battery hadn't leak on it...then after winter...it stopped working again....then replaced since the encoder motor was under warranty replaced it again and still nothing ...and then the switch....could this be the tccm? When you press the 4x4 high you can hear the tccm relay click...but hear no noise from the encode motor....any diagnoses i can run through b4 a by a used tccm..

thanks,
Nathan

i had a similar problem with my 99 sonoma. i would hear all the clicky clicky and the lights would stay on like they should but front wheels would not engage. same thing in 4 low. the vac actuator had a tear in the bottom of it so i replaced it thinking it would fix the problem but my front wheels still wouldnt engage. it turned out to be that the clip for the new actuator was defective and not holding onto the cable. i put the old clip on it and it works just fine now. something you might check.

Kyle's reply;

Thanks for the information! Hopefully it helps someone out!

Regards;
Kyle

I have a 98 Blazer which I cannot seem to pinpoint this vacuum issue I am having. The heat controls do not function properly (only comes out the dash and defrost). When I re-connect the vacuum line by the drivers side wheel well, there is a noise that seems to be coming from the drivers side front wheel. Also, it sounds like the truck is rumbling going down the road. When I disconnect it, it sounds perfect. Not sure if the 4 x 4 actually works, but it sounds as if it is engaging...

I have a '00 Blazer 2Dr. when 4x is engaged front diff bangs in and out as soon as I start driving any ideas?

Kyle's reply;

Take it to a mechanic?

Kyle

Trying to replace the front, driver wheel bearing on my 2000 Chevy Blazer. I can't get the hub to slide off the axle. I've even tried a hub puller with no success. I've done this repair before with no issues. Everything thats supposed to be out or off is (bolts, caliper, etc.). Any ideas?

Kyle's reply;

It's hard to say without being able to VERIFY that you have everything off/undone that needs to be. The hubs are pretty straight forward -- I have done both front hubs on mine with no problems (actually, twice on the passenger side as the NEW hub failed in like 2 months).

So, the hub won't come off the axle, or it won't break free from it's mating surface? If it's the first, then that means you have already broken the hub free, no? If the axle won't come out (you do have the large axle nut off, right?), then put the axle nut back on so the threads are not exposed and give it a good couple of whacks with a good sized hammer (a 2 or 3 pound sledge works well as it has a nice size head so you don't hit things you don't want to).

Good luck!

Kyle

Hello Kyle
I have a 1995 chevy blazer LT with 4 wheel drive. When i press the 4 low the light blinks on and their is a thump like sound under the truck. But the light doesn't stay on and when you puch thr 4 hi it does stay on and the thump also occurs but the 4 wheel drive doesn't work. Whay could it be I'll check the connector on the module on the passenger side or do you have an idea what i could be thanks Austin

Kyle's reply;

Your description of your problem sounds like a hundred others here...there is tons of information here for you to get started. All you have to do is read.

Kyle

We just got out first four inches of snow here in central PA and I pushed my 4hi button and got nothing. It worked fine last year. When I put it in neutral and push 4hi, all of the push buttons (2wd, 4hi and 4lo) will blink like six times. Is this some type of code? It will only do the blinking thing once. I like this forum and I've got some good tips. I'm gonna check the vacume lines now since it seems like the easiest thing to do. Thanks in advance.

Kyle's reply;

If the blinking is a code, I'm not aware of it.

Good luck!

Kyle

Hey Guys I have a 98 sonoma and the dame thing dose not
Go in to 4 hi. Can i just pull the cable under the batt
and Manuly put it in 4x4 or an easy way to do that?

when in nutral and i press the button you here a
clunk noise and the botton on 4 hi stays on. But it is
NO lock in. Its like you put it in HI and low back in forth over and over and maybe it goes in for a little and then kicks out. I would just rather Manuly putting it in. HOW???

Any way Jesse Thanks

Kyle's reply;

Pulling the cable under the battery will only engage the passengers axle. If the 4WD system is not working to begin with, engaging this axle will do nothing.

Sounds like the fork that moves your gears in the front differential may be your problem.

To manually put it in 4WD, get under the truck and disconnect the encoder motor. Once you remove the encoder motor, you should see a "shaft" (for lack of a better term) coming out of the transmission... that is what controls your 4WD. I can't tell you which way is which as I've never done it... but one way goes 4HI, one way goes 4LO and the other is 2HI.

Good luck.

Kyle

my fourwheel drive will not work, i was pushing the 4hi botton and the 4hi and 4lo blinking and then dropped into 4 lo, could not drive truck, bought a new transfercase acuator notor, had to manually switch trans into 2hi, truck now in 2hi, but switch on dash says 2hi, but i push the 4 hi button and nothing?

mine did the same and it had no codes up so i put a new mass air flow sencer on it and it runs great now hope it will help u

Hey, I just came across your page and seems really neat. Anyways I have a problem and hope you or one of your readers can help me. I have a 2001 Blazer LT. First off my gas gauge wont work, when im driving it sits on 'E' so i never know how much gas i have, i've replaced the Fuel pump twice and still nothing. HOWEVER when i turn off the engine and lock the car the gauge jumps from "e" to 3/4 full even if i have little or no gas.. another issue is my 4x4 wont work it says its on 4HI but i know its on 2LO and when i press the 2LO or 4LO buttons nothing happens except for the relay making a 'click' sound and i dont know if this is related but when i make tight turns either left or right i hear a 'thud' noise and feel as if i was driving thru some bumps, Now thats only when i make SLOW TIGHT turns. i have had the transfer case replaced, u-joints replaced not sure if those problems are related.... can someone PLEASE HELP ME........ im desperate lol

thanks
Noe

i have 2001 chevy s-10 zr2 and i cant get my front end to work ill push the button for 4hi and 4lo and the light come on like the front ends workin and i hear the transfer case click in but the 4wd still not workin ive read the post and looked the the vacuum lines but i cant find the one on the firewall and there wasnt one under my battery tray so i took my skid plate off and found some vacuum lines there and one that the nipple for a vacuum line is broke but i have no clue wat it is any help would b greatly apprecited

Kyle's reply;

Hi David;

Sorry, I have no clue either as I am not a mechanic and can only give you the information that I have first hand knowledge of.

Kyle

there is a recall with the abs malfunctioning on the four wheel drives, wouldnt hurt to see if your truck is covered

now for my problem...

can you tell me how to get the 4wd actuator cable out of the transfer case.. removed the three bolts holding it but cant get it out ... i know this thread hasnt been used but im hoping its still checked

Kyle's reply;

Thanks for the info -- I will check it out.

As for your problem, sorry, I've never removed a cable so can't answer your question.

Regards;
Kyle

Hey! Mine are doing that too. I don't know a soulution but i can tell you my mechannic said it's no big worry. I took it in for the first brake job ever at 230,000 kms and I thought that would fix the lights on problem when he ran it over he said it was some computer fault thing, but said not to worry it is still doing it's job simply sending an error code. I forget the name of the part but he said it was around 500 buck with labour to change it and make the lights go out... I am saving money and thinking if is worth it... SO if anyone has that part name or number try and post it up so I can find a used cheap one and all of us can stop starring at red and yellow lights.

Thanks

I have been chasing a problem with my 4WD for a while. It turns out that I had a bad clip with my new valve. When I replaced it with the old clip it worked great. Thanks for posting this or I wouldn't have found it.

Kyle's reply;

Awesome! Glad that some of the info here was able to help you.

Kyle

I have an 02 Blazer and I too have this 4x4 problem of the front axle not engaging and the lights are saying it is. Solution - don't buy anymore GM/Chevy garbage! No wonder they went bankrupt. It's making POS quality garbage cars like these! Cheap plastic interiors and low grade quality mechanisms. Good thing I only bought this thing for $1500 as a 2nd car for the winter...no wonder they dont hold their value. As soon as spring comes this thing is getting rid of. I'm sticking to my imports.

Kyle's reply;

Well, all I have to say is this;

1) I drive for a living. I understand that vehicles need maintenance and are under constant wear and tear. The Blazer, other than some electrical problems with the 4WD system, has been one of the best vehicles that I have owned. I have almost 300,000KM on my 2003 and it still drives like the day I drove it off the lot. I haven't a single complaint in regards to the S-10 Blazer.

2) You get what you pay for. You bought a $1,500 car. Do you expect it do drive and be like a $15,000 car?

3) When you're out of a job, I don't want to hear it. But hey, at least you'll be able to drive to the welfare office in your import!

Kyle

hi there i have a problem with my blazer not shifting into 4wd here the click click and motor switching just not locking in could my actuator vale be bad nopt pulling cable in could you e-mail me a possible problem or fix .

thanks Rob

Kyle's reply;

Hi Rob;

If the answer has not already been posted within the hordes of posts regarding the Blazer 4x4 system, then I don't have the answer you're looking for.

Regards;
Kyle

Hi I have a 94 s10 pickup that has pushbutton 4x4. When driving down the road it has no lights on. But when stopped and in nuetral it clunks right into 4x4, so it thinks that it is in 4x4 but actaully the front wheels aren't spinning. So i replaced the 4x4 actuator and the 4x4 pushbutton. But neither of them have seemed to be the problem. I don't see any cracks or splits in my vaccum lines also. So can you tell me why it isn't working?

Thanks,
Troy

Kyle's reply;

No. I am not a mechanic.

Kyle

When I press the 4hi button on the dash it blinks a few times and then clicks on and the light stays on but 4wd does not engage. If I press 2hi it clicks and the 4hi light goes off but the 2hi light doesn't light up. Same if I press 4lo, there is a click but the light doesn't light up. The end result is the same...she stays in 2wd. Last month it was intermittent at best. The inside 4hi button would blink and click on but 4wd did not engage. If you drove forward and then put it in reverse and drove back in the drive, you could hear the transmission finally switch to 4wd. It doesn't do that at all now. Any ideas?

hi, i have 1999chevy s10 pickup and my transfer case if engaging but my front end will not im geting Hi and Lo gear but my front wheels wont turn. i replace the acuator cable and the vacuume actuator. what could be my prb and i have checked the elctrical and hoses. could it be my hubs or cable still?

I have an 02 Blazer also and I have this 4wheel problem of the front axle not engaging and the lights are saying so, i had it checked out and its not a electrical problem says a code reader.. not sure what to do next, anyone know?
thanks
Ethan

I have had this problem three times on my 2002 ZR2 the four wheel drive switch sucks fluid out of the transfer case blowing the switch causing your 4 wheel drive to engage part way. Mine was covered under an extended warrenty but did run about $1000.00.

there is a vaccum line right down by ur brake pedle there is a clip that run defrost i have a 2000 blazer it did the same thing

ok i just got a 1999 chevy blazer i put it in 4hi do to the snow the day i got it and now it will not go back to 2 hi. i get the clicking noise and the lights on the dash says it is in 4hi. can some one tell me a few things about the lay out of the drive system such as where is the actuator, the encoder motor and such plz email me back

it seems like the 4x4 system is not very good in the blazers, but u have a problem with sometype of electrical systems with all makes and modles all i want to do is get mine fixed cause i really like it but husband wont let me keep it if it is goin to be a hasle plz help me at fire_frog_2005@hotmail.com

look under the battery, GM had this great idea to put a vaccum diaphram where acid can drip and burn a hole in it. check this and possibly go to a junk yard and find another vaccum switch. Have someone engauge 4x4 while your under truck so you can hear the switch engauging to be able to find it. its right underneath on the tranny. this is a 400 -600 part new. if you have a hole in the vaccum diaphram,, use a bike tire patch kit to fix this..a little 25 cent fiix for you.

i had this problem with my envoy 4x4 98 model,while driving i heard a slight grinding noise.it quit so i didnt sweat it.two wks laters it happened again but it was louder.i jacked up the driver side wheel,removed tire/rim,loosened the wheel hub nut.so it wouldnt be as hard to remove it when brakes are disassembled.see when i tore it down ball bearings fell everywhere,so i knew right then that was the prob.had to get wheel bearing hub assembly $100bux fixed it no problem.....hope this helps someone.

Kyle's reply;

Hi There -- thanks for the info!

Kyle

currently working on my 03 blazer. mine starting banninging in and out of 4wd. sometimes the cable gets a crack n the insulation and will cause a little rust to get under the insulation. this will hold the cable from diengauging or engauging the 4wd.holding it in between 2 and4wd untilthe drive bangs it out or in. one thing you might notice is the vaccum accuator will be totally collapsed or disfigured (mine totally got crushed under the vuccum pressure). take off cable from accuator, then crawl underneath and loosen 15mm bolts where cable goes into transfer case. this will allow you to see if rusty water has ran from the cable to the inside the gaurd. the cable is dissconnected in the same manner it is disconnected from the vaccum acuator. and i had to order mine from a dealer,,good luck with that!

Kyle's reply;

Good information there -- Thanks!

Kyle