4WD not working? Step inside.
- Thread starter fishsticks
- Start date
Welcome! Can you describe in detail what you see on the mode switch lights? Do they ALL flash for a second at start-up for the lamp test? Does one stay on and not change when you move the switch? Or are they all dark all the time?chucki said:
Any maintenance history? When was the last time you successfully tested the system?
chucki
Member
- Jun 22, 2014
- 26
all flash at lamp test. have only had vehicle for short time so not know the history. realize was dumb to purchase without history but is done now. have read up on the string here about 4 wheel drive won't work. figured was switch or tccm. have done both this morning and still nothing.have a lot to learn about this truck but is a fine ride and the wife likes it.
chucki
Member
- Jun 22, 2014
- 26
WELL. drove some and started and stopped some and the 2wd light came on. waited till I got back home and I can change it and it flashes then stays steady when change to AWD and 4H. 4L kept flashing and I changed back. will do more checking on it later. yeah!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The manual explains that 4LO has an interlock and you have to be in neutral and stopped (or rolling under 3 mph) to engage or disengage 4LO mode.
Now its time to change the tc fluid.
Now its time to change the tc fluid.
chucki
Member
- Jun 22, 2014
- 26
ok. got up this morning to run to work for a minute. 4wd service light on and no cruise. after shutting off and restarting believe I have an intermittent power problem. light off and cruise working. believe will turn key on and wait a couple of seconds then start the truck. will do some more reading about changing fluids and try to get it done this summer. I like being able to talk about it on here. very helpful. am liking my truck more.
chucki
Member
- Jun 22, 2014
- 26
still comes and goes but when it is on I have good 4x4. reckon when the key is turned on it powers everything and looks for correct amp use etc. and that is why it does not work like should? do I need a new battery as not sure how old this one is and am aware of issues with disconnect battery on these vehicles. or do I need to check connections for 4x4 things?
The system isn't smart enough to look for current draw, but it does check that the front axle actuator and the encoder motor give good position feedback signals, and that the PCM can communicate to the TCCM.
Any intermittent issue anywhere on a vehicle could benefit from unplugging/replugging all relevant connectors 4-5 times to clean oxidation off the contacts. It's also why we recommend that owners exercise their 4WD mode switch every month while powered off by rotating it CW and CCW 50-100 times, just to make sure it will work when you need it to.
The ultimate way to troubleshoot it is to carry the schematics and a voltmeter around, perhaps with the TCCM hanging down under the dash, and check voltages as soon as it goes flaky on you. It's the only way to find the real missing signal, and then diagnose how the signal went flaky. (short to ground, intermittent wire broken inside the insulation where you can't see it, bad wire crimp on the connector pin hidden by the plastic connector body, etc.)
Any intermittent issue anywhere on a vehicle could benefit from unplugging/replugging all relevant connectors 4-5 times to clean oxidation off the contacts. It's also why we recommend that owners exercise their 4WD mode switch every month while powered off by rotating it CW and CCW 50-100 times, just to make sure it will work when you need it to.
The ultimate way to troubleshoot it is to carry the schematics and a voltmeter around, perhaps with the TCCM hanging down under the dash, and check voltages as soon as it goes flaky on you. It's the only way to find the real missing signal, and then diagnose how the signal went flaky. (short to ground, intermittent wire broken inside the insulation where you can't see it, bad wire crimp on the connector pin hidden by the plastic connector body, etc.)
woodja
Member
- Dec 24, 2012
- 14
Mine started with a ringing "slip" sound while hunting and turned into a rolling crunch sound that i was pretty sure was coming from the front left side. 70k miles at that point. 17 miles up in the mountains, i crawled out luckily and I have driven in 2 wd ever since. Now 121,000 miles and I need my 4x working!. Time for tires and i have Mark's lift and a new set of Bilstein's to install. This will become a secondary driver rig with its primary use being mountain logging roads September - December.
Had it up on a lift in 4hi and it makes a steady clicking sound while tires rotate. Had an assistant listen and he swears its coming from the left side of the front differential. On the ground under load it is a hard binding "pop" that rings as it rotates and lets go.
Just did the left front off the ground test and do not have a good feeling about it. Front left up, right and rear on the ground, in 4 hi, transmission in neutral, tire moves approximately 2 degrees and does not spin. Splined disconnect is locking up. A lot of play at the cv axle connection at the left front tripot entering the diff. Axle shafts are 30k miles on Cardone replacements.
Jacked the entire front off the ground and spun the tires, one rotates ea direction. the clicking/crunching noise is coming from the left front side of diff according to my electronic ear.
While spinning, the front driveshaft rocks a little but does not rotate. Transfer case clutches are holding. TC (and front diff) fluids changed about the time this started around 70K after reading the Roadie's recommendation. It did not improve.
From those who have been through the front differential change, either by a shop or DIY, what is a reasonable amount of shop labor to expect on a quote to Remove and Replace the front diff?
I have the 2006 manual download thanks to Mooseman and all the tools except slide hammer shaft puller but I am leaning toward a reputable shop i know because i don't have a lift. I would like to get an idea of expected cost. I have an in at a LKQ parts supplier so i am planning to use as low mile replacement diff as I can find. I don't know the first thing about rebuilding a diff but may use mine as a laboratory to learn.
I will welcome any suggestions or recommendations you may have.
Had it up on a lift in 4hi and it makes a steady clicking sound while tires rotate. Had an assistant listen and he swears its coming from the left side of the front differential. On the ground under load it is a hard binding "pop" that rings as it rotates and lets go.
Just did the left front off the ground test and do not have a good feeling about it. Front left up, right and rear on the ground, in 4 hi, transmission in neutral, tire moves approximately 2 degrees and does not spin. Splined disconnect is locking up. A lot of play at the cv axle connection at the left front tripot entering the diff. Axle shafts are 30k miles on Cardone replacements.
Jacked the entire front off the ground and spun the tires, one rotates ea direction. the clicking/crunching noise is coming from the left front side of diff according to my electronic ear.
While spinning, the front driveshaft rocks a little but does not rotate. Transfer case clutches are holding. TC (and front diff) fluids changed about the time this started around 70K after reading the Roadie's recommendation. It did not improve.
From those who have been through the front differential change, either by a shop or DIY, what is a reasonable amount of shop labor to expect on a quote to Remove and Replace the front diff?
I have the 2006 manual download thanks to Mooseman and all the tools except slide hammer shaft puller but I am leaning toward a reputable shop i know because i don't have a lift. I would like to get an idea of expected cost. I have an in at a LKQ parts supplier so i am planning to use as low mile replacement diff as I can find. I don't know the first thing about rebuilding a diff but may use mine as a laboratory to learn.
I will welcome any suggestions or recommendations you may have.
IllogicTC
Member
- Dec 30, 2013
- 3,452
If it was off-and-on, it wouldn't be so bad, even with some special tools required. But thanks to placement, a lot of crap has to come off before the mechanic can hit prime time with the differential itself. Obviously some may still quote a price that disqualifies them from The Price is Right, but it isn't going to be a very pretty number either way.
I have searched the forums here and that old site so many times hoping to find a magic bullet but there is no way around it, I'm gonna be cutting a big check soonI'm having intermittent issues with my 4hi in my 2003 TB Ext. The issue being 4hi hasn't been workin, but 4lo and Auto4wd do work. This problem started this past winter and never really got to it, but now it's time. This happened once before about 4 years ago and a new switch solved it. So I thought a new switch would fix it again, not so much. I went through the flow chart in the beginning and here are the results: with front left tire off the ground in 4hi, both actuators do make noise, spinning the tire makes the driveshaft spin to the TC. I lift both fronts off the ground, and the tires rotate in opposite directions when spun by hand. With left front off the ground in 4lo, the tire will not spin. When going back into 4hi from 4lo, the front tire will not spin. But going from 2hi to 4hi, the front tire will spin the drive shaft will move. So would this be an encoder/ actuator issue, TCCM or TC problem? The fluid in the TC was changed at 60,000 as well as both diffs.
Sure sounds like the encoder motor is not locking up the transfer case clutches in 4HI. Could be the encoder motor brake died, or an internal problem in the transfer case. A GM Tech II or a high end scan tool should be able to exercise the encoder motor through all its modes and confirm whether the brake is working or not. Do you have any local buddies you can try an encoder motor swap with?
Unfortunately I don't have anyone to swap encoder motors with. Trying to get one of my buddies, who is a service manager at a GM dealership to take a look at it with his tools. But he's been busy lately, so trying, with your help to diagnose this on my own. Without just swapping parts. Thanks Roadie.
Finally, got the 4wd fixed. It ended up being the encoder motor. The GM tech said the motor wasn't fully locking when engaged in 4hi or 4lo. So 20 minutes in the drive way and got her working. Thanks for the help, Roadie
gruvedaddy
Member
- Dec 28, 2011
- 30
Don't know if you are still having intermittant 4X4 issues but i had the same problem a few years ago that i posted on the "other" forum. My problem was the 4X4, Blower for the HVAC, and i believe cruise were coming and going all at the same time. I narrowed it down to the piece of shit fuse block under the rear drivers side seat. I can't for the life of me find it at the moment but i had a schematic of the fuse block wiring and notice that all the items that were not working happened to be fed from the same main bus line (or power feed for lack of a better term). Due to GM's infinate wisdom of not leaving ANY slack in the wiring i could not get anywhere under the block to find where the problem was. So after locating the schematic and the correct wires in the wire bundles i bypassed the fuse block on those circuits and spliced in inline fuses of the correct size and have not had a problem since in that respect. However....(see next post)chucki said:
gruvedaddy
Member
- Dec 28, 2011
- 30
So, anyway...i'm back yet again with more 4x4 issues. Read through many forums and don't see the answer so here's what's up: Service 4WD light has been on. I Turn ignition on and i get all the lights on the 4x4 selector switch illuminated for 3 seconds and then all they go off. With the ignition still on I turn the switch from 2HI to 4Hi and i hear nothing under the truck at either location that i should. I have power at both fuses front and back and have pulled and reinserted the #8 fuse numerous times with the ignition on and off and still no dice. So, possibly a bad TCCM? Don't have anybody to swap one out with to test if that's it. Could low fluids initiate the 4x4 SEL?
Welcome back. There are no TC or diff fluid level sensors. Certainly sounds like a bad TCCM. What year?
If you download the manuals available from member Mooseman, they would have the pinout of the connector at the TCCM so you can make sure it has power. No guarantee a good fuse delivers power to the module. I've also posted the schematics many times, that you can find with a Google images search for "tccm schematics".
If you download the manuals available from member Mooseman, they would have the pinout of the connector at the TCCM so you can make sure it has power. No guarantee a good fuse delivers power to the module. I've also posted the schematics many times, that you can find with a Google images search for "tccm schematics".
gruvedaddy
Member
- Dec 28, 2011
- 30
Thanks Roadie for the quick response. Its an 02 TB, so no surprise if its a bad TCCM. I did get the service manuels from mooseman. Ill check the pin outs on the TCCM for power and the probably shop around for a TCCM. Ill update what eventually solves the issue.
I have no 4wd. I did. But you all know. First snow storm, no worky. Lol it makes both noises described. Lights function perfectly. But. I do know I have a bad wheel bearing. Front left. It whines when I turn right, yada, yada. (I know my way around a vehicle to a certain extent.) now you guys are exceptional with your information. Are you certain a faulty wheel bearing can cause a no lock issue? Thanks for your responses.
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
Sorry its been 8 hours but I have used 4x4 plenty on a bad wheel bearing so I bet it's something else.
There is a great flow chart on Offroadtb.com for when 4x4 does not work. Go through it and let us know what you find.
There is a great flow chart on Offroadtb.com for when 4x4 does not work. Go through it and let us know what you find.
Yea I'll have to put it up, all the lights work etc. I hear the shift under. And the actuator up front. Thanks fit the heads up on the flow chart.
i have 2005 envoy with all wheel drive. the all wd, 4wh,and 4wl are not working. turning the switch the lights blink then go solid but the front wheels do not turn. there is a clicking sound coming form under car ,sonds from front. any suggestions?
My issue was the disconnect. The bearings were gone. Which I'm assuming was causing the actuator to not engage (basically a push rod, which is one of the two electric motors you should hear whining, if indeed everything else is working properly. One under the center, and the other to front) I heard both these noises. But my front wheels wouldn't turn. Thought the actuator was broke (cheaper and MUCH easier of the two parts to fix) but. It was the disconnect. Which was an absolute nightmare. It was basically welded in there ( there's a circular appendage that "slides" into the front differential.pappap55 said:
I ended up pulling the shaft out. (After popping the tie rod end off the hub assembly in order to spin it back enough to have the room to pull the shaft out from the disconnect) . that's when the fun starts. I pulled the bolts holding it in place. Noticed it wasn't even wiggling, preceded to use a slide hammer, with no luck, I then started tapping around to see if it would break loose... Bench cast aluminum it "broke" loose alright.. In pieces. It was then I noticed the bearing was destroyed. And looked as though the fork was broken aswell . Still the rear half of the disconnect was welded in place still. I then spent the next two hours with an air chisel trying to break the rest of it out. When it finally gave and split. I was elated. The new disconnect, I took apart, (split in half by removing the bolts that hold the two pieces together) and greased everything I could put grease on. It went back in quite nicely, though I do hear a slight clunk sound when I start to roll, (with or without 4 wheel engaged) but the 4 wheel was working great. Apologize for the length of this post. But listen for the front actuator before replacing the while disconnect.
Hoping this thread is still active. I have gone through the diagnostics here for a 4wd non working issue, largely shared or linked to by roadie. something seems to be missing. http://www.offroadtb.com/articles/tech-docs/what-is-wrong-with-my-4wd-system/
Before I get into a lengthy post, I keep seeing that changing TC fluid is a must, but no info on what symptoms or effects occur if that doesn't happen. I don't have a maintenance schedule for the vehicle and don't know when or if its changed. Encoder motor and actuator both engage (both replaced). Lights are solid on the selector, service 4wd comes on shortly after driving. Fuse #8 has been pulled while running to try and clear any (none show up) codes. On a jack both wheels spin freely and independently while in 4wd. I am suspecting the transfer case or splined disconnect (wheels are supposed to lock of this is the issue) after all this reading, but relatively little has come across with respect to the transfer case. Can the fluid be the issue on its own? If its a transfer case issue is it likely to be the clutches?
Before I get into a lengthy post, I keep seeing that changing TC fluid is a must, but no info on what symptoms or effects occur if that doesn't happen. I don't have a maintenance schedule for the vehicle and don't know when or if its changed. Encoder motor and actuator both engage (both replaced). Lights are solid on the selector, service 4wd comes on shortly after driving. Fuse #8 has been pulled while running to try and clear any (none show up) codes. On a jack both wheels spin freely and independently while in 4wd. I am suspecting the transfer case or splined disconnect (wheels are supposed to lock of this is the issue) after all this reading, but relatively little has come across with respect to the transfer case. Can the fluid be the issue on its own? If its a transfer case issue is it likely to be the clutches?
Likewise, hoping someone is still looking at this thread. Followed the steps at the beginning. Step 2, no sound from disconnect actuator. Pulled it off and plugged on to a second TB I have. Still nothing. Great, easy fix. Buy new actuator, connect it, still nothing. Connect new actuator to second TB, works fine so it isn't a bad part. What now? Connector looks good, no corrosion or broken wires, harness still in plastic tubing. Any measurements I can take at the connector? Trace wiring back to ??. Fuse?
Any assistance appreciated.
Any assistance appreciated.
Mooseman
Moderator
Fuses should definitely be checked. What are the switch lights doing? Is the service 4x4 light on? What year is your truck? 2002 had bad TCCM modules.
OK after lurking for a while And owning an 03 Tb that has given me very little grief. I bought an 02 tb for my mom so she can have 4x4 for the winter.. I drove it home and got a service 4wd light.. so I start thru the usual procedure. and will explain.... some one tell me what or where i missed.
every time the key is turned on the lights in the switch flash and 1 stay on.. it usually will default to a4wd no matter where the switch is.. switching from a4wd before the service 4wd light comes on it will flash the desired light then light the services light and default back to a4wd I have been able to get it to go to 2wd once in a while. but usually it goes back to A4wd... I couldn't hear the encoder so i bought and changed it... now on key up i can hear it. I also changed the front axle actuator and heard its whine the first time I keyed up... while changing the actuator i did take and make sure i could push in the shift fork and it moved roughly 3/4" in and sprung right back out.... Im going to pickup oil from dealer $7.50 qt tomorrow and change the Tcase lube..
Any thoughts insight comments... does this sound tccm or am i pulling a tcase?
every time the key is turned on the lights in the switch flash and 1 stay on.. it usually will default to a4wd no matter where the switch is.. switching from a4wd before the service 4wd light comes on it will flash the desired light then light the services light and default back to a4wd I have been able to get it to go to 2wd once in a while. but usually it goes back to A4wd... I couldn't hear the encoder so i bought and changed it... now on key up i can hear it. I also changed the front axle actuator and heard its whine the first time I keyed up... while changing the actuator i did take and make sure i could push in the shift fork and it moved roughly 3/4" in and sprung right back out.... Im going to pickup oil from dealer $7.50 qt tomorrow and change the Tcase lube..
Any thoughts insight comments... does this sound tccm or am i pulling a tcase?
Mooseman
Moderator
Tiggerr
Member
I'd also grab a 4WD switch from the pick a part I've seen where they've gone wonky too.,
While your changing oil in TC I'd do your diffs too.,, especially if you have no history on it.
Me personally I change all fluids/filters..,and update all normal maintenance items... when I buy a vehicle... unless I know where it came from...
While your changing oil in TC I'd do your diffs too.,, especially if you have no history on it.
Me personally I change all fluids/filters..,and update all normal maintenance items... when I buy a vehicle... unless I know where it came from...
Thanks guys I wondered about both but since the lights in the switch stayed on i wasnt sure about tccm....
I sure hope i can get this 02 to be as trouble free as my 03 has been ...
I sure hope i can get this 02 to be as trouble free as my 03 has been ...
2002 Trailblazer 208,000 miles. I replaced the TCCM about a year ago with a 2003 one. Also replaced front drive shafts about a year ago.
Started vehicle after stopping at Home Depot and the "service 4wd" plus the ABS and brake lights all came on. Brakes seem to work fine so drove vehicle home.
I rarely use 4wd and have not used it for about 3 months. Need to get in the habit of using / testing it every month.
Tried pulling fuse 8 for +1 minute - no difference.
The lights on the switch flash as expected when turned on. When moving from 2 wd to any of the other settings I can hear what I think is the encoder. Roughly same noise for all the different settings. The light on the 2 wd stays on and the light above where the switch is flashes. Also applies to 4 lo (in neutral). I do not hear two different sounds as expected.
I am thinking this is the actuator? Also wondered why the ABS and brake warning lights would come on for a 4 wd problem? Torque Pro is not showing any codes.
Any thoughts comments?
Thanks
Started vehicle after stopping at Home Depot and the "service 4wd" plus the ABS and brake lights all came on. Brakes seem to work fine so drove vehicle home.
I rarely use 4wd and have not used it for about 3 months. Need to get in the habit of using / testing it every month.
Tried pulling fuse 8 for +1 minute - no difference.
The lights on the switch flash as expected when turned on. When moving from 2 wd to any of the other settings I can hear what I think is the encoder. Roughly same noise for all the different settings. The light on the 2 wd stays on and the light above where the switch is flashes. Also applies to 4 lo (in neutral). I do not hear two different sounds as expected.
I am thinking this is the actuator? Also wondered why the ABS and brake warning lights would come on for a 4 wd problem? Torque Pro is not showing any codes.
Any thoughts comments?
Thanks
Mooseman
Moderator
Torque would not show codes other than P powertrain codes. Download Car Gauge Pro which can read other codes. The lights have to be on to be able to read those.
I was doing some more research on this and found some threads about the Service 4wd, ABS and Brake lights coming on being caused by the ignition switch.
This was usually accompanied by the blower not working. I checked my blower and yup, it is not working.
I replaced the ignition switch probably 6 - 9 months ago however there are many reports of them failing regularly so seems like that is the best place to start.
Mooseman - thanks for the response. Do you know if I need Car Gauge Pro or can I use the free Car Gauge Lite?
This was usually accompanied by the blower not working. I checked my blower and yup, it is not working.
I replaced the ignition switch probably 6 - 9 months ago however there are many reports of them failing regularly so seems like that is the best place to start.
Mooseman - thanks for the response. Do you know if I need Car Gauge Pro or can I use the free Car Gauge Lite?
Mooseman
Moderator
Thanks Mooseman, I'll keep it in mind for the future.
Problem solved, it was the ignition switch. I actually replaced it Dec 2014 with one from Advance Auto that had a Lifetime Warranty so fortunately, it did not cost me anything for the part.
Everything is working as expected including the 4 WD.
Problem solved, it was the ignition switch. I actually replaced it Dec 2014 with one from Advance Auto that had a Lifetime Warranty so fortunately, it did not cost me anything for the part.
Everything is working as expected including the 4 WD.
I am not familiar with the newest 4wd systems but, should the front drive shaft spin freely while locked into 4wd on my 05 Chevy Trailblazer? The vehicle is on the ground and in Park while testing. In older vehicles the front drive shaft doesn't spin but, I am very unfamiliar with these newer setups. The front actuator and encoder motor on the transfer case are making the noises that they should but, still have no 4wd. The lights for the 4wd switch are working and it is lighting up in each selection.(2WD, A4WD, 4HI, 4LO)