hey I was on the highway last night and I suddenly lost all power to the wheels. sounded like the engine was just reving and there was no longer any connection to the drivetrain. when I switch it through the gears it does feel like the transmission is changing gears but still no connectivity in any gear. I have been having a failing 4x4 system recently in my other post but I do not know if this can be related to that. we were leaning to a bad transfer case for that situation but are not 100% yet. could a bad transfer case cause no power to the rear wheels?
2003 envoy I6 lost all power to the wheels while driving
- Thread starter juiceboxxx26
- Start date
ok I I put it up today and took a look nothing is bropken or damaged by eye. but if I spin the driveshaft from behind the transfer case then the driveshaft in front of the transfer case does indeed spin as well. this leads my to the transmission. up on the jacks in drive the car does absolutely nothing at all. no tires spin or anything. no grinding until you try to put the car into park and then it grinds.
IllogicTC
Member
- Dec 30, 2013
- 3,452
Shelled out internal components in the transfer case, at the input shaft or planetary gearset.
I'm sure you know how park works, you bring the vehicle to a stop and shift to park. When your brakes have no physical link to also stop the transmission output shaft, it's still spinning in there as soon as it's in gear, so trying to put it in park would definitely start gnawing at the gears or more likely the parking pawl.
My suggestion for safely shifting to Park in this scenario would be to first shift to neutral and wait 45-60 seconds just in case the transmission takes some time to spend down, then briskly flip it up into Park. However this will not secure the vehicle as the link is broken, you should consider setting your parking brake to truly hold the vehicle in place while you prepare your fix.
I'm sure you know how park works, you bring the vehicle to a stop and shift to park. When your brakes have no physical link to also stop the transmission output shaft, it's still spinning in there as soon as it's in gear, so trying to put it in park would definitely start gnawing at the gears or more likely the parking pawl.
My suggestion for safely shifting to Park in this scenario would be to first shift to neutral and wait 45-60 seconds just in case the transmission takes some time to spend down, then briskly flip it up into Park. However this will not secure the vehicle as the link is broken, you should consider setting your parking brake to truly hold the vehicle in place while you prepare your fix.
IllogicTC said:
SO WHAT ABOUT THE TRANSMISSION? when I put the truck into drive I get absolutely no response from the front driveshaft coming out of the transmission. wouldn't that be broken as well?
the roadie said:
ok o how do I know If its 100% to be the transfer case? is there anyway to test it? I don't want to pull it out and then have it be the transmission all along
IllogicTC
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- Dec 30, 2013
- 3,452
juiceboxxx26 said:
You already said you likely have a bad transfer case. And if you have a bad transmission the transfer case has to come off anyway as part of the replacement procedure, so what have you got to lose? You already said it feels like the transmission is properly shifting, and the transmission has a bit more computer oversight to help find problems than the transfer case does.
Pull the transfer case. It's pretty much a must to test it. Then spin the input and see if there's any spinning on the output(s). You said the outputs seem to be linked, so the likely culprit is a shredded input gear assembly.
IllogicTC said:
ok so drop the transfer case then spin the input shaft to be 100% input shaft is the one that connect to the tranny? correct?
any other tests I can do ?
IllogicTC said:
ok done dropped the transfer case down on my chest and sure enough when I spin the input that would come from the transmission nothing else did anything nothing else spun at all. so I guess the transfer case is bad. can you explain to me what let go inside the transfer case that would cause this and where should I go about getting a new transfer case?
juiceboxxx26 said:
also I have another question now there is a hose coming from the top of the tranny that wasn't connected to anything. what is this hose for? where does it go? what does it do? there was another hose that connected to the transfer case but there was two
IllogicTC
Member
- Dec 30, 2013
- 3,452
Inside the transfer case, the input shaft engages a range collar which is moved by the high/low shift fork to either select 1:1 (normal) ratio, or 2.69:1 (4LO) ratio. In normal mode, the range collar is pushed forward toward the front of the transfer case. When switching to 4LO, the range collar moves rearward, disengaging the normal range teeth, and then engaging the teeth on the 4LO.
It could be the input shaft, the range collar, the planetary gearset maybe... a bunch of things.
You can either run on down to the stealership and get one for $1500 (not installed), or take a chance down at the junkyard. It can come from an Envoy or TrailBlazer or a couple other platforms, AS LONG AS it's 4x4. AWD does not count! It would have the shift selector knob just like you have, either on the dash or in the center console right above the cup holders, depending on the model. Again, junkyard parts have no known service history so it's a gamble, but a gamble that'd save you at least $1000 or more on the part.
I believe those hoses that are mounted on TOP of the units mentioned are for ventilation purposes. They are left just hanging there, it prevents improper pressure buildup from occurring in parts of the transmission where it shouldn't build up.
It could be the input shaft, the range collar, the planetary gearset maybe... a bunch of things.
You can either run on down to the stealership and get one for $1500 (not installed), or take a chance down at the junkyard. It can come from an Envoy or TrailBlazer or a couple other platforms, AS LONG AS it's 4x4. AWD does not count! It would have the shift selector knob just like you have, either on the dash or in the center console right above the cup holders, depending on the model. Again, junkyard parts have no known service history so it's a gamble, but a gamble that'd save you at least $1000 or more on the part.
I believe those hoses that are mounted on TOP of the units mentioned are for ventilation purposes. They are left just hanging there, it prevents improper pressure buildup from occurring in parts of the transmission where it shouldn't build up.
IllogicTC said:
yeah im prob going to take a gamble with a junkyard one. I saw some on ebay that had the milage posted but who knows how accurate they are . my truck has 124000 miles on it already runs strong though. no noises from the engine or anything that's the only reason I don't feel the need to junk it. you have been a lot of help I appreciate it really. im going to pick one of these up and see what happens
Get I have another question about the transfer case motor. Will the encoder motor still switch at all if there is an internal problem as I have inside the transfer case? Maybe that is the reason that I can not see the motor spin when switch 4wd gears.
If the transfer case has internal damage that jams the mode control shaft, then the encoder motor will be jammed. But it should still work fine if unbolted from the transfer case.
IllogicTC said:
Picked up a t case today everything works great when I spin the input shaft from tranny both rear shaft going to the rear wheels and shaft going to front wheels soon too. Picked up two quarts of autotrack 2 and also the t case came with a motor on it so I think I'm just going to use that one.
Just rotate the TC mode control shaft. Getting stuck in neutral mode would be a unique failure, though. Much more likely to have internal carnage.IllogicTC said:
IllogicTC
Member
- Dec 30, 2013
- 3,452
juiceboxxx26 said:
It's nice to see you on your way to getting your truck back on the road
Smart move to do a fresh fluid change as part of your install, then it starts out with a known service interval. I don't see what it'd hurt to just use the encoder it has.hey I got the t case installed everything works good now. now truck wont start its 23 degrees out now it cranks but wont kick over is there a sensor on the transfer case that would effect this??? before I had thwe t case in the truck would start right up now t case is on truck cranks fine sounds like it wants to go but just wont kick over
Transfer case has no such sensor. Tranny has the Park/Neutral switch on the driver's side. Fuel pump harness could be involved. Do you remember poking at anything under there or jostling any harnesses?
The_Roadie said:
ahh start actually does try and start fumbles but doesn't run it boggs and fumbles . smells rich out of the exhaust,. got a cam code umm cam lean or something
IllogicTC
Member
- Dec 30, 2013
- 3,452
juiceboxxx26 said:
It shouldn't affect a p0014 unless perhaps you're low on oil or something.
p0014 - Cam Over-Advanced. The actual and desired cam positions delta are >3.5 degrees after stabilization time of 2-6 seconds is met.
What commonly causes this is the CPAS. Check out the Article Submission area, there's a thread on cleaning the CPAS, it could very well be up your alley. If your CPAS in deemed to be shot, a new one cost me $44 (including S/H) on GMPartsDirect. Part number is 12615873, it'll be called a valve or sprocket or some such on there but that IS the part.
ok cleaned out throttle body really good truck started up!! now I have a p0300 arndom misfire WTF!!! I changed the cam position sensor and now I have a misfire random mis smh!! 4x4 light came on too
ok here is where im at!
I now have a random misfire P0300 and the truck runs like total crap but it starts right up. Also I still have a service 4x4 light on!!!! only when I switch the 4wd selector switch when the key is in the off position then switch the key to on is when I get movement from both the front actuator and the encoder motor. I can get the truck to go from 2wd to A4WD but cannot get the truck to go into 4hi. I put two quarts of transfer case auto trac 2 in the transfer case. at this point I have no idea where to go now with this 4wd system.
IllogicTC
Member
- Dec 30, 2013
- 3,452
juiceboxxx26 said:
On the misfire, did you change the sensor or the Camshaft Position Actuator Solenoid? The CPAS is what actually does the dirty work making the actuator move; the sensor just provides feedback on where the camshaft's VVT is. If the CPAS is still bad, it may still crop up a p0300, did you try cleaning it? Also, did you reset the PCM after cleaning the throttle body? It may still be trying to work with the settings for the dirty throttle plate.
It seems to me that the transfer case is having an issue pressing the clutches to 100%. If you switch to A4WD and then back to 2HI, does everything work okay without a service lamp?
[GMAP][/GMAP]
I'll try cleaning cpas tomorrow, I replaced only the cps. Yes I reset the PCM
If I switch from a4wd to 2wd nothing happens unless I turn the key off to on. But it does shift. I do have a service 4x4 light on
IllogicTC said:
I'll try cleaning cpas tomorrow, I replaced only the cps. Yes I reset the PCM
If I switch from a4wd to 2wd nothing happens unless I turn the key off to on. But it does shift. I do have a service 4x4 light on
ok fixed the misfires I had two bad coils. I still have no 4wd service 4wd light is still on.i cannot get the truck to go into 4hi. it is stuck in A4WD . when I switch jack up the front of the car and spin one tire the other side does indeed spin in the opposite direction.
with the truck jacked up its passenger side only I can indeed spin the tire. but the truck says it is stuck in A4WD
when I spin either side of the front tires the drive shaft going to the front of the transfer case does indeed spin.
now I feel like I have started all over again.
with the truck jacked up its passenger side only I can indeed spin the tire. but the truck says it is stuck in A4WD
when I spin either side of the front tires the drive shaft going to the front of the transfer case does indeed spin.
now I feel like I have started all over again.
IllogicTC
Member
- Dec 30, 2013
- 3,452
juiceboxxx26 said:
With misfire issues fixed, and the vehicle at least able to complete the powertrain circuit, you may feel like you're still on square one but you're actually further along than you were. If it's at least in driveable condition it's miles above just sitting there
I know you're not off the rough path yet but it's all about trying to keep on keeping on instead of throwing your hands in the air.I would also suggest checking the 4x4 switch. It could be just an issue with connector seating, contacts needing cleaned up, or maybe a whole new switch. If everything checks out good on the switch, let us know. No need to shotgun the part if everything checks out of course.
I never changed the 4wd switch but I do not see a reason that it would be bad, if I change the switch and then start the car it will at least try to switch I can hear both the new actuator and the encoder motor working. it will change to a blinking light over the selected gear and then go back to the 4awd.
I have replaced the actuator
various encoder motors
used transfer case with 80,000 miles on it. front diff seems to be good as well as the rear.
not sure if my front disconnect is good since I cannot get it into 4hi.
also replaced tccm and had it reprogrammed $200 waste
is it possible that the transfer case I got is bad? and how can I even tell what gear I am in since my car says its stuck In 4awd. how do I know if it is even in 4 awd. how long should I unplug the fuses before the tccm resets itself??
I have replaced the actuator
various encoder motors
used transfer case with 80,000 miles on it. front diff seems to be good as well as the rear.
not sure if my front disconnect is good since I cannot get it into 4hi.
also replaced tccm and had it reprogrammed $200 waste
is it possible that the transfer case I got is bad? and how can I even tell what gear I am in since my car says its stuck In 4awd. how do I know if it is even in 4 awd. how long should I unplug the fuses before the tccm resets itself??
juiceboxxx26 said:
also I would like to add that both before my car broke down and after changing out the transfer case my truck was stuck in A4WD
IllogicTC
Member
- Dec 30, 2013
- 3,452
juiceboxxx26 said:
One hour should be plenty of time for a TCCM reset. If it goes into A4WD the front disconnect should be good. The only time the front is NOT engaged is in 2HI mode, so a switch to 4HI wouldn't affect it. May have something to do with not getting into 2HI though.
IllogicTC said:
ok how do I know I am even in A4WD? I cannot tell when im driving it. Also when should A4WD be used?
it isn't going into 4AWD. it may or may not be in A4WD but it says im in A4WD I cannot switch to any other gear. any ideas on what I should look at next? maybe I should start all over? really need this fixed.
If the switch is the only indication you have you're in A4WD mode, then you really can't tell by driving it unless you're on snow and ice and force wheel slippage by goosing the throttle. The splined disconnect should be engaged in A4WD, 4HI, and 4LO mode, and the "spin one front tire and see if the other one spins backwards" is the test for that.
One should basically NEVER use A4WD mode. It's not a true AWD mode like many vehicles have, and running in that mode when you don't have a risk of wheel slippage can wear out the transfer case clutches prematurely. If it's slippery enough you can use 4HI, use 4HI. If it's not, drive in 2HI.
To get to the absolute bottom of this will require some detailed work with a voltmeter at the back of the TCCM and out at the front axle actuator probably. If somebody writes up a theory of operation, can you follow along and measure the voltages on a bunch of pins? Have you downloaded the schematics from here and understand a bit about the how the system works from the schematics? If not, we can talk you through it.
Like landing a plane after the pilot has a heart attack - how hard can it be?
One should basically NEVER use A4WD mode. It's not a true AWD mode like many vehicles have, and running in that mode when you don't have a risk of wheel slippage can wear out the transfer case clutches prematurely. If it's slippery enough you can use 4HI, use 4HI. If it's not, drive in 2HI.
To get to the absolute bottom of this will require some detailed work with a voltmeter at the back of the TCCM and out at the front axle actuator probably. If somebody writes up a theory of operation, can you follow along and measure the voltages on a bunch of pins? Have you downloaded the schematics from here and understand a bit about the how the system works from the schematics? If not, we can talk you through it.
Like landing a plane after the pilot has a heart attack - how hard can it be?
The_Roadie said:If the switch is the only indication you have you're in A4WD mode, then you really can't tell by driving it unless you're on snow and ice and force wheel slippage by goosing the throttle. The splined disconnect should be engaged in A4WD, 4HI, and 4LO mode, and the "spin one front tire and see if the other one spins backwards" is the test for that.
One should basically NEVER use A4WD mode. It's not a true AWD mode like many vehicles have, and running in that mode when you don't have a risk of wheel slippage can wear out the transfer case clutches prematurely. If it's slippery enough you can use 4HI, use 4HI. If it's not, drive in 2HI.
To get to the absolute bottom of this will require some detailed work with a voltmeter at the back of the TCCM and out at the front axle actuator probably. If somebody writes up a theory of operation, can you follow along and measure the voltages on a bunch of pins? Have you downloaded the schematics from here and understand a bit about the how the system works from the schematics? If not, we can talk you through it.
Like landing a plane after the pilot has a heart attack - how hard can it be?
Ok let's go I have no idea about the schematic but from my t case replacement and problem with 4wd I'm pretty knowledgeable about the system. Walk me through this and I will solve this.
