4WD not working but no Service 4wd light

[Fless]

What should those numbers be? Or how would I interpret them?

@Dusty_GMT800,

Kinda rough picture, but it would look something like this.

 

[Dusty_GMT800]

Ok, so now I just drove the truck again, just because I was curious I hit the 4lo button in neutral, and then the truck drove as though it was in 4lo (revving higher, driving slower, etc.) So could this mean it's the front diff not locking? Still have to get it on a lift and find out if the front driveshaft is spinning, but this has me feeling a bit hopeful

Edit: This truck is weird man

 

[rockola1971]

Ok, so now I just drove the truck again, just because I was curious I hit the 4lo button in neutral, and then the truck drove as though it was in 4lo (revving higher, driving slower, etc.) So could this mean it's the front diff not locking? Still have to get it on a lift and find out if the front driveshaft is spinning, but this has me feeling a bit hopeful

Edit: This truck is weird man

Sounds like it went into 4lo and yes the tahoe would rev and feel like its in a low gear because the rear axle is slaved to the gear reduction (4lo) within the Tcase. Your front driveshaft could be removed and your rearend would still be in 4lo so bottom line is that your 4lo works but still not enough information yet to determine if your front axle is at fault or chain inside tcase.

4wd 99-02 has NP246
4wd 03-07 has NP246E (Enhanced)
246 behind a 4l60e is NOT interchangeable with one that was behind a 4L80E. Different number of splines on input shaft of Tcase.
What year was yours again? Do you have AUTO 4wd button?

But since im a gambling kinda guy. My bet is on the front axle actuator or the electrical circuit to it. Typically when a chain gets loose enough and just before failure you usually hear alot of noise before the end comes.

 

[Dusty_GMT800]

Sounds like it went into 4lo and yes the tahoe would rev and feel like its in a low gear because the rear axle is slaved to the gear reduction (4lo) within the Tcase. Your front driveshaft could be removed and your rearend would still be in 4lo so bottom line is that your 4lo works but still not enough information yet to determine if your front axle is at fault or chain inside tcase.

4wd 99-02 has NP246
4wd 03-07 has NP246E (Enhanced)
246 behind a 4l60e is NOT interchangeable with one that was behind a 4L80E. Different number of splines on input shaft of Tcase.
What year was yours again? Do you have AUTO 4wd button?

But since im a gambling kinda guy. My bet is on the front axle actuator or the electrical circuit to it. Typically when a chain gets loose enough and just before failure you usually hear alot of noise before the end comes.

I have an 02, with the auto 4wd button, I'm hoping to get some time soon to get under the truck and poke around, really hoping it's the actuator.
I haven't heard any abnormal noises from underneath nothing loud or otherwise

 

[Dusty_GMT800]

Just curious, if the transfer case shifts into 4lo and drives like it's in 4lo, why would the front tires not receive power? Assuming the front diff actuator is all good.

 

[rockola1971]

Just curious, if the transfer case shifts into 4lo and drives like it's in 4lo, why would the front tires not receive power? Assuming the front diff actuator is all good.

In 4lo the Tcase provides gear reduction to both the front and rear end. Your rearend is connected to the transmission via a shaft internally through clutches and gears. Your front end is connected to the transmission through the clutches and output shaft via the chain ultimately ending in the front driveshaft output propeller. So you could disconnect the front driveshaft so the front wheel would never be powered and your rearend would still be in gear reduction (4lo) and drive funky and slow with lots of torque. So the 4lo working tells you nothing about what your problem is with your vehicle. It does not isolate your Tcase chain or the front actuator.
You could put your tahoe in 4hi and get it all locked in and then park it and let someone drive it forward a few feet while you lay down beside it with a flashlight and look up under and see if the front driveshaft is turning. If it aint then you got problems in the Tcase. If it is then your problem is up front (actuator or electrical to actuator). You could lay a mirror underneath the vehicle and look down at it as the vehicle is moved forward in 4hi to see if front driveshaft is moving or not. This way would keep your old lady from running over your head.

 

[Chubbs]

You could lay a mirror underneath the vehicle and look down at it as the vehicle is moved forward in 4hi to see if front driveshaft is moving or not. This way would keep your old lady from running over your head.

LmAo

 

[Doubeleive]

In 4lo the Tcase provides gear reduction to both the front and rear end. Your rearend is connected to the transmission via a shaft internally through clutches and gears. Your fornt end is connected to the the transmission through the clutches and output shaft via the chain ultimately ending in the front driveshaft output propeller. So you could disconnect the front driveshaft so the front wheel would never be powered and your rearend would still be in gear reduction (4lo) and drive funky and slow with lots of torque. So the 4lo working tells you nothing about what your problem is with your vehicle. It does not isolate your Tcase chain or the front actuator.
You could put your tahoe in 4hi and get it all locked in and then park it and let someone drive it forward a few feet while you lay down beside it with a flashlight and look up under and see if the front driveshaft is turning. If it aint then you got problems in the Tcase. If it is then your problem is up front (actuator or electrical to actuator). You could lay a mirror underneath the vehicle and look down at it as the vehicle is moved forward in 4hi to see if front driveshaft is moving or not. This way would keep your old lady from running over your head.

lol, nobody invests in jack stands anymore?

 

[rockola1971]

lol, nobody invests in jack stands anymore?

How would I know what you or anyone else owns. But no, I dont "invest" in jackstands because I have access to a lift.

 

[Dusty_GMT800]

How would I know what you or anyone else owns. But no, I dont "invest" in jackstands because I have access to a lift.

Wish I had lift access, but I do have plenty of stands.