silverado 4WD does not work

[lkm7764]

After reading many posts on here for the last few hours i have decided that it's time to ask for help. I have a 2001 Silverado Z71 with auto trak, the front wheels do not get power to them when in 4WD. I have done several of the tests listed in the various posts for TC problems. The lights on the switches all work, there is no DTC codes at all, started the truck and cycled thru AUTO, 2HI, 4HI, and 4LO and back and jumped around between them several times. every time the TC can be heard and felt switching between the gears. test drove in 4LO and was rolling in the proper gear, but no power to the front wheels. (Tested by visual and also tried to climb a small hill that i play on all the time and the rear wheels just spun in the dirt) Any help would be greatly appreciated. I'm leaning towards chain broke or jumping or gears stripped. Thanks to all in advance.

[MT-2500]

Welcome to AF
Any service transmission or transfer case lights on?
how many miles on it?
Has the special GM transfer case fluid ever been serviced/changed
In 2W High or 2W low check for front drive shaft locking in.
If it is check the front actuator electric motor for locking in front axles.
Check for 12 volt power to actuator and for shifting in in 4W and out in 2W.
Look wiring and fuse and related over real good.
Let us know on the upper test and checks.

[lkm7764]

update on symptoms, while driving about 25 mph tried shifting into 4HI and the noise was deafening, sounded like trying to go into reverse, came to a stop and felt the shift complete into 4HI started driving again and the grinding noise returned

[lkm7764]

Originally Posted by MT-2500

Welcome to AF
Any service transmission or transfer case lights on?
how many miles on it?
Has the special GM transfer case fluid ever been serviced/changed
In 2W High or 2W low check for front drive shaft locking in.
If it is check the front actuator electric motor for locking in front axles.
Check for 12 volt power to actuator and for shifting in in 4W and out in 2W.
Look wiring and fuse and related over real good.
Let us know on the upper test and checks.

no service lights are on almost 180,000 miles on it transmission was replaced appx 20,000 miles ago fluid leak around the motor and have had to add to it only twice in the last year, 1 quart each time. where are the fuses located for the actuator?

[MT-2500]

Originally Posted by lkm7764

no service lights are on almost 180,000 miles on it transmission was replaced appx 20,000 miles ago fluid leak around the motor and have had to add to it only twice in the last year, 1 quart each time. where are the fuses located for the actuator?

We need the results of the test as outlined in first post before we can help.

Auto or manual transmission?
The auto transfer case uses special GM Blue transfer case fluid and should be serviced ever so many miles.
Has it ever been serviced?

Fuses can be found in under hood fuse box and inside cab fuse box.
Always check all fuses and for 12 volt power on both sides of fuse.

Do not use 4L or 4H on the road/dry payment.
Shifting into 4H and 4L always stop and put trans in neutral or rollback and forward.

[lkm7764]

thanks will get out there and test them tings and post what i find

[lkm7764]

Originally Posted by MT-2500

Welcome to AF
Any service transmission or transfer case lights on?
how many miles on it?
Has the special GM transfer case fluid ever been serviced/changed
In 2W High or 2W low check for front drive shaft locking in.
If it is check the front actuator electric motor for locking in front axles.
Check for 12 volt power to actuator and for shifting in in 4W and out in 2W.
Look wiring and fuse and related over real good.
Let us know on the upper test and checks.

ok there are no transmission or transfer case lights on, fluid has never been changed or serviced to my knowlegde (bought this truck 9 months ago), in 2HI front drive shaft turns freely, locks but can be turned by hand almost an inch and a half in 4HI or 4LO, front actuator on front diff has power to it and the motor sounds like it is working when going in and out of 4WD, all wiring and connections look good and there is power to all connections, checked and replaced the 4WD fuse just to be sure. i can find no reason on the above checks for it not to be working. and as stated before almost 180,000 miles on it

[j cAT]

Originally Posted by lkm7764

ok there are no transmission or transfer case lights on, fluid has never been changed or serviced to my knowlegde (bought this truck 9 months ago), in 2HI front drive shaft turns freely, locks but can be turned by hand almost an inch and a half in 4HI or 4LO, front actuator on front diff has power to it and the motor sounds like it is working when going in and out of 4WD, all wiring and connections look good and there is power to all connections, checked and replaced the 4WD fuse just to be sure. i can find no reason on the above checks for it not to be working. and as stated before almost 180,000 miles on it

drain the transfer case fluid inspect for metal debris and color [blue]

drain the front diff inspect for metal debris and an amber color....

if the fluids are black or very dark gray this will need disassembly to determine the extent of the damage...


as stated never operate these 4wd vehicles on solid dry pavement in any 4wd operation ....except for a very ,very short testing distance....


just a side question are the tires on the vehicle matched as to size and amount of wear ????

[lkm7764]

Originally Posted by j cAT

drain the transfer case fluid inspect for metal debris and color [blue]

drain the front diff inspect for metal debris and an amber color....

if the fluids are black or very dark gray this will need disassembly to determine the extent of the damage...


as stated never operate these 4wd vehicles on solid dry pavement in any 4wd operation ....except for a very ,very short testing distance....


just a side question are the tires on the vehicle matched as to size and amount of wear ????

tires are 35" BFG all terrain and mounted on 16.5 wheels, i dont know if this makes a difference but the truck has a 7" suspension lift and a 3" body lift, tires are all evenly wearing, pressure gets checked at least once a week and rotated every 10,000 miles

[j cAT]

Originally Posted by lkm7764

tires are 35" BFG all terrain and mounted on 16.5 wheels, i dont know if this makes a difference but the truck has a 7" suspension lift and a 3" body lift, tires are all evenly wearing, pressure gets checked at least once a week and rotated every 10,000 miles

thanks for that quick response on my question....

since you have a significant amount of mileage and the fluid maintenence is not known it is very very possible you will need a new transfer case/front diff as many have had your problem before totally locking up the wheels...be careful as if this occurs you may get into an accident...do as I suggested and if metal particles are found in large pieces and the fluid is filled with metal ,you must investigate if repair or replace...is needed..

some have had this occur and it took out the transmission....

[lkm7764]

thanks for your help, i'll make an appt tomorrow to get it into the dealer for service

[j cAT]

Originally Posted by lkm7764

thanks for your help, i'll make an appt tomorrow to get it into the dealer for service

I hope this is a small item ....the dealer may be too expensive in cost to justify repairing this vehicle ...take time to make your decision ,, if you must spend XXXXX.oo to complete repairs...or buy another vehicle...

good luck