tb02 4wd does not work

[jimbob4411]

i'm in a desperate mode here tried to go up a steep hill when i moved the switch to awd nothin then tried to move switch to 4wd nothing the lightd dont even come on does any one here have any ideas iam not sure what is going on seems i;m stuck in 2wd only

[ScarabEpic22]

Welcome to the site.

I have an 02 as well, and have heard of the problem you are having, but I need more information. Does the transfer case engage? (With the TB on, radio off, door open, when you turn the switch can you hear a suction noise?) Are there any lights on on the instrument panel- Service 4WD or similar? Does the light move from 2HI to AWD, 4WD, or 4LO when you move the switch there? Also, has it done this before? Can you wait and then it will engage?
Also, what TB is it? It is a 2002 Chevy TrailBlazer (LS, LT, LTZ) (SWB or EXT)4WD with xx,xxx miles, (with, without) the locking rear differential (RPO code G80 in the glovebox), and (3.42-GU6 in the glovebox, 3.73-GT4, 4.10-GT5) gears, and I (have, dont have) an extended warrenty.

I think I have an idea what is wrong, but I need to know more information about your TB.

[jimbob4411]

thanks for quick response
ltz 4wd 142000 km engine replaced at 60 k by gm waranty issue blown engine past extended warranty no warning or service lights
no suction noise
no lights on switch
w/o differential lock
my wife just got home with the tb i looked at the tb i'm thinking could it be a fuse
to dark now to check i have nenver had this problem before
thanks for doing this

[ScarabEpic22]

Thanks for the updated info.

So, you are saying that there are absolutely no lights on your 4WD switch? If so, then definately check the fuses for a blown one. In the resources section of the site, there are TSBs and more information about this problem, but I have a few ideas if these arent the problem.

OK, I think your problem is one of two things:
1. Cheapest fix would be to purchase another 4WD switch and install that. If you arent getting the light to move to another place on the switch, then this is probably your best bet for now. I think they cost like $30 from the dealer, or maybe you could pick on up from a junkyard/pull apart yard for cheaper.

2. Your transfer case needs to be reprogrammed. Go to the dealer and have them look and see if your transfer case needs to have the software upgrade performed. If so, pay for it to be reprogrammed. If it already has the most current software loaded, then dont have them do anything unless they find something wrong.
3. If the new switch or reprogramming doesnt fix it, unfortunately it would probably be the transfer case module. They are know for going bad, however not as common as the fan clutch going. This thread explains more about it:http://chevytruckworld.tenmagazines.com/forums/topic.ten-id-110992-s-4wd_light_flashing.

Hope you figure it out, and any more questions I am here!

[ScarabEpic22]

This is a little ironic, as the same thing happend to me today as I was getting ready to go. The TB started, but the Service 4WD light came on, and there were no lights on on the 4WD switch. Tried restarting, no luck, light still on. Drove for 35min, stopped for 3.5 hours, restarted, and no light on on the dash, and the 4WD selector was working. I think there is something wrong, as my TB has done this once before. I think I am going to replace the switch and see if it helps, but since it hasnt done it in 3 months, I wonder if it will be worth it investing in a new switch. I need to get that temp guage and pull the codes from tonight. Grrrrr, probably will end up going to napa and see if they will read the code for me.

[Trailblazin]

ok well ihad the first problem for a few weeks then absolutely nothing. My 4X4 swtich lights don't even turn on. Although sometimes when i switch of the car and put the swtich into hi4 or low4, it does change as I when I turn the steering wheel, I feel ALOT of pressure and each tire moves at a different time.

Anyway I have the amber sign that looks like the 4X4 with the spanner next to it. I took it into the dealerhsip and they told me nothing was wrong. They even did tech2 and said the computer was reading everything fine. hmmm, its kinda strange.......

I want it to work and that sign to go away, its not a pretty sight when driving, and i have a feeling the bulb is gonna break soon the amount of time its been on :(

any ideas on this??

[jimbob4411]

thanks scara for all your help looking forward to chatting with fellow tb;rs i really like the trailblazer but man does it ever have issues i have never owned a vehicle that has had so many problems all my work has been warranty work but now i am paased that part so with my latest problem the 4wd no lights i went out pulled out the fuses reseeded them then started the tb boom lights camera action evrything works fine now but will advise dealer to reprogram software as per a new recall

my only request from anyone would be the link about the recall on the rear door latch because i just paid 500 bucks because the read door would nt open the remote would not unlock or release the door the dealer told me it was the whole lock assembly that needed replaced but if i can get proof of the recall maybe my problem was related with the recall

thanks jim

[ScarabEpic22]

Glad to know that it fixed itself!! Mine did the same thing, makes me mad.:mad:

Cant help you with the second q, might want to make a new thread.:m2:

[2002BlkLTZ]

Erik,

The codes for the Transfer Case Control Module aren't pulled by alot of code readers out there. The next time your truck does this (service 4wd light on) get under the hood (with the engine off) and pull the fuse listed as ATC (I think it's number 8). Reseat the fuse and see if the service 4wd light goes off (switch lights come back on). If so, you either need a flash or the module replaced. I just went through this with my truck. If you can find a code reader that will read it, there's codes in some of the TSB's. I don't remember the numbers, but the code the dealership had on the service invoice for my truck was the one that said "other/unknown problem, consult a GM repair facility" in the TSB. I needed a module.

[ScarabEpic22]

Erik,

The codes for the Transfer Case Control Module aren't pulled by alot of code readers out there. The next time your truck does this (service 4wd light on) get under the hood (with the engine off) and pull the fuse listed as ATC (I think it's number 8). Reseat the fuse and see if the service 4wd light goes off (switch lights come back on). If so, you either need a flash or the module replaced. I just went through this with my truck. If you can find a code reader that will read it, there's codes in some of the TSB's. I don't remember the numbers, but the code the dealership had on the service invoice for my truck was the one that said "other/unknown problem, consult a GM repair facility" in the TSB. I needed a module.
Thanks, I will do that when it does it the next time. How much did it cost you to get the module replaced?

[2002BlkLTZ]

$440 or so, from the dealership. I was already going to be out $78 for the "diagnosis" and reflash if that's what it needed, so I went ahead. I could've gotten the module cheaper on GMPD.com but I *suspect* the module would still need flashed from the dealership prior to or after being installed, which would've made it a wash when I was already out the $78 if I had to pay another $78 to have a new module flashed. My dealership had this module in stock, which suprised me, and also tells me it must be a common problem.

[Trailblazin]

well this might be an option to check out...i just went to the delarship so they could look at my 4X4 and they told me they needed to change the actuator as there was electricity getting to to swtich but nothing going back so no signals were being picked up.

it should cost around $150-$200 for a new one, might be worth a try to ask them to check it before they do any other major jobs and charge u a mint. :m2:

[ScarabEpic22]

Thanks for the reply. I dont think I will worry about this until it does it again, which as you all know will be tomorrow morning as I am leaving.:mad: If it does it again, I think I will go to the dealership and have them check it out and offer a diagnostic. If it is something simple like the switch, I will order one online, but something like the actuator going would have to be a dealership job.

[jimbob4411]

well i guess my tb 4wd is not a unique problem seems like there are a few tb's with almost similar can you imagine ,you guys are only a small fraction of owners,
i recently took my tb back to the dealer my service advisor hooked up some sort of machine ran a check on my tb found nothng so he called in a mechanic who ran a similar check but slightly more advanced he discovered that the vehicle lost power to the transfer case module when i reseeded the fuse atc number 8 it reactivated the module and did not affect the updated software. so be careful before you get told its something else sometimes little problems are really little problems
thanks to all who provided such valuable and informitive assistance
ps he also cleared the log that stores something dont remeber what he said though:laugh:

[stanggt00]

I have the same exact problem. I had no lights on the 4WD switch and no service 4X4 light on the instrument cluster. I was told to reset the ATC fuse and after doing that the lights on the switch cylced through, went out again and the service 4x4 light came on. I dropped it off at the dealer tonight anticipating needing the software upgrade.

Question, if I need a software upgrade due to the stupidity or lack of intellegence by GM when they built this thing, should I have to pay for it? I can understand if the TCM went out that it will have to be replaced and I would pay for it, but software that should be usefull through the life of the car with no components changed? That sounds rediculous and like a scam. [Here is your TB, now in 4 years your gonna have a software problem that will happen out of warranty and you will have to pay us to fix it]

[ScarabEpic22]

Welcome to the site!

As for paying, what year is your TB, and how many miles? (You can edit your truck in your user CP at the top left of the site)

[stanggt00]

Its a 2002, bought it in Aug 01 with 33K miles on it. It is out of warranty as far as I know. I am waiting for Chevy to call me with what they found.

[stanggt00]

Just got the call from Chevy. It needs a new TCM module and software upgrade, $440. +tax :( I was hoping it would be just the software but they say both. I hope I dont have this problem again any time soon.

[ScarabEpic22]

Just got the call from Chevy. It needs a new TCM module and software upgrade, $440. +tax :( I was hoping it would be just the software but they say both. I hope I dont have this problem again any time soon.
Unfortunately, that sounds about right.:( You sometimes need the software, but the other part of the time you need the entire TCM and the software. I think when I get the tranny guage in the other thread (it reads codes), I will see what the code was that it threw the other day and see if I need the software. If so, shouldnt be a problem, as I think I need some other ones as well because none have been performed in about 1.5 years.

[xxfile]

.After reading the thread I have now some ideas. Im not sure when mine quit but there are no lites on thr 4X4 switch and no extra service lites on the dash.
I pulled and checked fuse #8 and now im hoping that it just fixes itself.
Im not looking forward to buying the module/software. but there is about 8 inches of snow in my driveway right now.
as you may notice i too am new here
good site.

[xxfile]

Hey just removed and replaced fuse #8 while truck was running and voila now 4X4 works fine

[thor]

if the indacator light, for the switch is not lit, and the fuses are good , it's the switch, i had to replace mine

[2002BlkLTZ]

if the indacator light, for the switch is not lit, and the fuses are good , it's the switch, i had to replace mine

Not always true. It can also be the Transfer Case Control Module (TCCM) needing reprogrammed or replaced. The module doesn't "wake up" on key-up (when you turn the key and it checks all systems) and pulling the #8 fuse under the hood cuts all power to it. You'll need either the module reflashed or replaced. Although, if you're Service 4X4 light is not on I might go with the switch first, as it's far cheaper.

[ScarabEpic22]

Well, it happened all day yesterday and today again. I had a Service 4WD light on every time I started my TB (but not immediately, I had to shift into gear first) and sometimes there was a light on on my switch and others not. I was running errands yesterday and today, so I probably turned it on/off 10+ times. I tried pulling the #8 ATC fuse the first few times to get it to switch back from A4WD to 2HI and it worked for a min, but then it died and the light came back on. What really pisses me off is that the last time I was coming home from Home Depot and everything was fine, no lights and the 4WD worked. I think my switch is on the fritz and will goto the dealer early next week and get one.

[Gaspar]

Today when I needed the most 4x4 (snow & icy roads, family in car,etc.) that stupid 4wd service light was on and no yellow light on the switch... :mad: damn!!!
The funny thing is that once the TB warmed up a bit I restarted the engine and the light would turn off and everything was working wonderfully...
Today is cold: -21c (-5f), but truthfully that shouldn't matter...
I'll take the TB to the dealership on Monday.

Fortunately I paid the 'select' kind of extended warranty that should cover everything..

Out of curiosity,for the ones that know more about this issue do you think that is a switch or actuator/transfer case problem? (so I have some ammo. when I talk to the dealership)

Thanks
Gaspar

[ScarabEpic22]

I really hope mine is the switch, otherwise I dont know what I will do if it isnt that or a software update. I really dont want to spend $500 on repairs on my TB, but if it comes to that, I dunno....(coughTBSScough)

[lowered envoy]

I have seen tons of these trucks with the problem and the reflash has cured all of them.The module doesn't wake up sometimes.pulling the fuse and reinstalling it resets the atcm.Get it reflashed and try it. if it doesn't fix it and it needs the new atcm you are only out .5 labor.and if it fixes it you save 50 bucks.
Ciao,
Chris.

[Gaspar]

Yesterday the dealership couldn't work on my TB so I came back with the 4wd Service light on, when I pulled in the garage I restarted the engine and suddenly it was working beautifully, while I was testing the system I left it on 4Lo. Today in the morning as usual the 4wd service light was on but unlike the other days the 4Lo mode remained!! So I could barely made it to the end of the street and made a U turn (well multiple moves involved)
So I'm there -21c (-6f) wondering what the problem is.. then I remembered this thread and people talking about a fuse...

Well to make this story short I found fuse #8 blown so I used the wiper fuse just to change the 4Lo to 2wd mode!

I'm on my way to the office! Although I found the problem I'm still debating if I should take her to the dealership to see if the can find the problem.

Thanks TrailVoy!
Gaspar

[impalajunkie]

my 02 TB has this problem.
the Service 4WD light comes on and off, its very odd. Sometimes the 4WD works, other times it doesn't and the service light comes on.
I've found that usually the 4wd WORKS when its warmer. Don't know.
Tried the fuse thing, didnt work. I just pulled it so i dont have that damn service 4wd light on anymore, its been driving me crazy for months.

[ScarabEpic22]

my 02 TB has this problem.
the Service 4WD light comes on and off, its very odd. Sometimes the 4WD works, other times it doesn't and the service light comes on.
I've found that usually the 4wd WORKS when its warmer. Don't know.
Tried the fuse thing, didnt work. I just pulled it so i dont have that damn service 4wd light on anymore, its been driving me crazy for months.
Yeah, I noticed that too, whenever it gets below 25F, it has the potential to act up more than if it is above 32F.

[Gaspar]

Tried the fuse thing, didnt work. I just pulled it so i dont have that damn service 4wd light on anymore, its been driving me crazy for months..

Yeah, I noticed that too, whenever it gets below 25F, it has the potential to act up more than if it is above 32F.

Well today I took the TB to the dealership and I received the call from the service consultant:
Hi Gaspar,
We found the problem! The TCCM (transfer case control module) must be replaced. The only issue is that extended 'select' warranty doesn't cover that so you'll have to pay 700 bucks including labour...

At that point my blood pressure started going nuts.. WTF!!
After $3100 CDN dollars in extended warranty they give me that *****..
I took a deep breath and explained that I had bought the car from them less than a month ago...yada, yada...
... so he talked to the boss and as a special thing the charges will go to the warranty, I just had to pay the $100 deductible..

Can you believe that? Those guys have the guts to lie like that when in the GMPP brochure its clearly specified that the transfer case is covered (powertrain warranty level).

So if you have any kind of GMPP warranty take it to the dealership. I can scan the brochure and you can show it to them if necessary.

At the end of the day I'm happy, the 4wd works beatifully although in the notes the tech. specified the fuse #8 was not blown, huh? I saw that with my own eyes...

Anyway.
I'm happy...

-Gaspar
ps. sorry for the long post, I just had to vent.

[Envoy Fan]

Read a similiar situation on another forum. No light at all on a TB 2wd or 4wd or anything. Owner talked to a tech. Tech told him to remove the two battery cables + & - and touch them together. This resets the computer. Fixed his problem.

I haven't ever had the need to do this personally, and all cautions and restrictions apply. :rolleyes:

[guano2]

light out 2wd only pulled #8 atc fuse plugged back in [key off] started it. tb says oh yeah ive got 4wd. that was a few wks ago no probs. with that so far.:cool: thanks for saving my butt again guys:hail:

[bigpimpin571]

do you know where transfer case module is located on a 02 tb lt

[bigpimpin571]

[QUOTE= do you know where i can purchase a transfer case module for my 2002 tb beside the dealership, they want to charge $550.00 for the module at the dealer.

[doug]

My 02 TB has the same issue. When I bought the truck, it would oddly try and shift itself into 4LO by itself while I was at highway speeds. Not cool.

I ended up having the module software upgraded by the dealer, which fixed it.. until a few days ago.

My 4WD switch has no lights, and there is NOT a service 4WD idiot light on. No noises whatsoever when the switch is engaged.

The local stealership wanted to charge me several hundred bucks to fix, but after reading this thread, I fixed it myself by pulling and resetting the #8 Fuse.

4WD now functions fine again! TrailVoy +1, Stealership 0

[02redhawk]

If the #8 fusse trick doesn't work (or only temporarily works; ie, the prob comes back soon), the TCCM (transfer case control module) is ~$175 from GMPartsdirect or Fred Beans online. Takes about 30-minutes to replace, start to finish.

[NotForBling]

When you guys are talking about issues with the 4WD do you guys mean
4HI or 4LOW???? All you guys are saying is 4WD.

Just wondering....in case it ever happens to me I want to know when to check the #8 fuse,lol.

[the roadie]

do you know where i can purchase a transfer case module for my 2002 tb beside the dealership, they want to charge $550.00 for the module at the dealer.Ebay is your friend. You can find 4WD selector switches for $25, encoder motor/module for $150, and entire transfer cases WITH the motor for $500.

[doug]

When you guys are talking about issues with the 4WD do you guys mean
4HI or 4LOW???? All you guys are saying is 4WD.

Just wondering....in case it ever happens to me I want to know when to check the #8 fuse,lol.

I had two seperate issues. the first issue involved the tb shifting itself into 4LO (or at least trying). that was fixed at the dealer for free, and IIRC, there was a TSB about it.

The second, more recent issue which involved the #8 fuse was different. I simply had no power to the 4WD selector switch. It was all dark, and turning the switch to the various positions provided no love. The #8 fuse apparently runs the transfer case computer, and removing the fuse for a few moments seems to force a reboot, which unhangs it.

I wonder if the transfer case computer runs windows... might explain a few things

-douglas

[MichEnvoyBoy]

If the #8 fusse trick doesn't work (or only temporarily works; ie, the prob comes back soon), the TCCM (transfer case control module) is ~$175 from GMPartsdirect or Fred Beans online. Takes about 30-minutes to replace, start to finish.

Good info, Redhawk. Btw, Im in Macomb county also (Roseville) :cool:

[deemer57]

I noticed the last few days that my 4WD switch light is blinking in both 2wd and 4 WD. It seems to be intermittent. If you put it in park the light stops blinking.

Could this be the switch itself? If so, is it hard to replace? I do not receive any warning lights like service engine soon.

Thanks,
Dominic:)