2001 gmc seirra 1500 z71 problems

Caleb1 · August 3, 2017

Caleb1

Today, 08:38 PM

4wd selector switch does not show what it is in. It's in 2wd but doesn't show. Tried actuator and switch neither worked. Bought truck with 4wd not working hoping someone can help me here. Also my truck does not display a service 4wd message. Another thing is it doesn't read park, neutral, third or 1st. It reads park only if I first turn truck on after that it doesn't read unless it sits running for awhile then it will show back up. Thanks in advance

Swimmer8366 · August 3, 2017

Sounds to me something on the Transmission is fooling with you.....can't think of name for it brain fart .....sensor actuator on shift cable....off transmission?

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Caleb1 · August 4, 2017

Okay thanks I will try to look into that

benjaminearle · August 22, 2017

I'll add to this topic instead of creating a new one.

I've got an '01 Silverado 1500 Z71 with 292,000mi on it. It's always gotten between 11 and 12 mpg running in medium traffic turning 305/70/17s

It's always (since I've had it from 280,000mi) had to be coaxed into 4x4 and won't come out unless you stop, shift back to 2hi and put it in reverse and then there's a big clank/thunk and you can feel everything unbinding.

Well, the other night i was attempting to flash someone driving at night without their lights. I was going about 45mpg and by mistake hit the 4hi button instead of the light switch. It was like i did a 4-2 downshift and dropped the clutch. Got slowed down and out of 4x4 by selecting and reversing but ever since it's felts tight and it whines/moans at all speeds.

I haven't yet had a chance to check diff fluid - trans is fine - does the trans share with the xfer case?

Anyway, anybody had a similar problem? If the front drive is f'd can I just pull the front driveshaft or should i pull the half-shafts too (or instead) and just run 2wd for the time being?

Thanks

Sunnysidebeach · August 23, 2017

1999 GMC Sierra 1500 factory lift 4 inches, 5.3 240k

I've had to replace the 4 wheel drive switch, and the 4 wheel drive actuator that attaches to the transmission. That fixed the problem your talking about. After running it a week in 4 wheel auto in heavy deep snow last spring, I had to replace the front end differential.

benjaminearle · August 23, 2017

So replacing the actuator and switch fixed the problem or only when you replaced the front diff was the problem fixed?

1999 GMC Sierra 1500 factory lift 4 inches, 5.3 240k

I've had to replace the 4 wheel drive switch, and the 4 wheel drive actuator that attaches to the transmission. That fixed the problem your talking about. After running it a week in 4 wheel auto in heavy deep snow last spring, I had to replace the front end differential.

Sunnysidebeach · August 24, 2017

So replacing the actuator and switch fixed the problem or only when you replaced the front diff was the problem fixed?

The 4 wheel drive problem was fixed.

The front end replacement happen due to the all the seals leaking and replacing it was cheaper than the labor to pull it apart and replace the seals.

Chubbs878 · August 27, 2017

If the front drive is f'd can I just pull the front driveshaft or should i pull the half-shafts too (or instead) and just run 2wd for the time being?

Thanks

Do not drive an early GMT800 4WD model with the CV shafts removed. The original wheel hub is designed to operate with CVshaft holding it from the inside. If you drive the truck with CVshaft removed, the hub will self-destruct, most likely while you are in motion. Plenty of threads warning against this with first hand accounts of resulting carnage!

As for the case clunking, binding, & so forth; it possibly is in need of a rebuild given the symptoms. It's never a bad idea to replace the encoder ring, rephase the encoder motor assembly and reprogram the TCCM. The encoder ring is $50 or so and any DIYer can replace it with a couple hand tools. They always burn out at some point if yours hasn't already. Moving on, these TC units are prone to destruction wherein the oil pump spacer rubs a hole in the rear case half, draining the oil and grenading the internals. At the very least you want to drop the TC & install a cheap "case saver" pump-rub eliminator piece to avoid this catastrophe. It's just another 1 of those things that will eventually happen if you do not attack preemptively. While you have the case halves split you are able to examine the internals and replace seals/bearings/clutch pack/etc. after that it will go for another 200k.