[DeerMeadowFarm]

The questions keep coming the more I drive it! My old truck had manual lock hubs; if the hubs were locked in you had 4WD as soon as you engaged the lever. The new truck has auto hubs (I assume). When I engage the lever, it takes a little while for the indicator to light and for the 4WD to engage. My buddy told me that it takes a few revolutions of the wheels for the front hubs to lock in. When I drove up an icy hill last night I pulled the lever into 4-Hi. For w few seconds I was still spinning the rear wheels before the 4WD kicked in. When it did, it clunked. Was this because my rear wheels were spinning and the truck was under power when the hubs locked in? It hasn’t clunked any other time I have engaged the 4WD. My buddy says I just have to change my driving habits; engage the 4WD before I start to spin; anticipate situations where I may need 4WD and engage it before hand. Does this make sense or is something wrong with the truck?
Also, when I shift into reverse, the truck hesitates a second or two before it actually begins to back up. The used car dealer told me he checked and topped off all the fluids so I assume the fluid isn’t low. Of course, he told me a bunch of stuff that he didn’t follow up on either so I think I’ll check it myself at lunch.
I’m starting to like the truck; it rides nice, etc. but I’ve got a 60-day warranty to figure out what could be wrong. My local mechanic, who I trusted, just moved so I don’t even know whom I could have go through it. The local GM dealer would most likely charge me 2 hours of labor to “inspect” the truck and I wouldn’t be surprised if it never made it into the garage. Suggestions?

 

[wyldman]

The newer GM's don't use any sort of hubs,they have a thermal actuator that engages the front diff.

It takes a few seconds to warm up and engage 4WD.You should not be moving at this point,just wait until the light comes on.They have a new updated electric actuator which is much quicker.It might be a good idea to replace it now,before it fails.You can also get a cable actuator,so it's manually operated.

The trans delay in reverse may be worth taking to a trans shop for a free inspection,and get an estimate.If there is something wrong,now is the time to do it while you still covered under the warranty.

 

[DeerMeadowFarm]

Wyldman - So are you saying that I can't shift "on-the-fly"? How much of a job is it to replace the actuator? Is it a GM service job or can anyone do it? Are there advantages to the cable vs. the newer actuator vs. what currently is in the truck?

 

[ratlover]

Cable are more dependable, dont fix it unless its broke though IMO Replacing the actuator is an easy job.

You can shift on the fly but its advisable to take your foot off the gas and not shift under power especially if the rears are spinning. It genneraly best to shift in while at a slight roll going straight and with your foot off the gas but you can put it in at any speed really. I guess we have differing oppinbions on what is ok

 

[ratlover]

I also personally dont ussualy engague 4x4 unless I am stuck or having a problem. Most of the time I'm in 2wd. If there is a place I know I will have a problem with I will go to 4 or if there is a spot I know will be nasty I will ussualy put it in if I want the extra controll you sometimes get without having your assend walking all over the place.

Personal preference but I try to stay outa 4x4 as much as possible but I do "anticipate" things as much as possible.

I have noticed that sometimes if I get stuck and put it in 4x4 while stoped(if I'm stuck i dont enguage wheile I'm spinning!!!) if I give it a very small amount of throttle I will still be in 2wd. I then lift and let it sit for a second and try again to see if 4x4 is enguaged. Its bad to have the back tires spinning and have the fronts enguaged buecause they will be stoped and when they enguage they will start to spin imediatly. Thays why its fine IMO and actuall I believe advisable to shift while you are rolling and the fronts and backs are at the same speed, seems to make things enguage quicker. I also try to shift to N and coast, let it enguage then put it in gear so there is as little binding as possible. I always do this when going to 4low and i think the truck makes you be in N but if I try to do it from a stop it seems to take much longer than from a slight 2mph or so roll.

 

[Fast Eddie]

My 94 K1500 does the same thing, but recently it hasn't disengaged 4wd as well as it should. I'd have to stop, go into reverse for about 15', then it would disengage.
It might have something to do with the way I engage it. Rat, the next time I use 4wd, I'll try your method..

-e

 

[ratlover]

its probably binding on disengagement. Happen on fairly grippy pavement?

Using the same method of a slight roll in N and trying to disenguage should probably do it. Or disengaging it in some slippery stuff or and gravel or the like.

Or the actuator is being a PITA

 

[urethane dino]

Chris not to be one to ever step on your toes, but didnt GM switch to an electrical CAD sometime around 94/95. My 98 is electric. Yes it does take a few seconds to engage, and if the wheels at spinning, the clunk will be noticable. It is not a major issue. If you engage 4wd before hand the engagement will be smooth. You can shift on the fly in 4 hi, but must stop and put the tranny in Neutural to engage 4 low.
Dino

 

[wyldman]

I don't know the exact year of the change,but I think it was later,like 1997 or 98.

 

[GLS]

I basically have the same truck as Deermeadowfarm.

So what is the proper way of engage FWD on my truck? I don't have any problems getting it in/out, but would like to know if i'm doing it wrong.

I thought it was shift on the fly, but I go easy on it. To engage 4hi, I usually engage it at a slow roll, not usually more than 15mph. A few seconds of rolling and it usually is in. If I am at a stop I can put it from drive to reverse and back into drive and it usually engages.

For 4lo, I put it in neutral. I had been going from 2hi to 4lo in neutral and letting it roll slowly, but it took quite a while to engage. I now first put it in 4hi (if not already) and then into 4lo, it engages right away.

 

[michfan]

Shift on the fly

OryanO,

This truck is a shift on the fly style 4x4 system. You can actually shift it into 4Hi from 2Hi at speeds up-to 50-55 mph. It will take a moment to engage into 4Hi because the actuater is a vacume style, and takes a couple revolutions for the system to engage. If you want to shift it into 4Lo, you do need to bring the truck to a complete stop, shift the truck into park or Nuetural. It will shift quicker into 4Lo if you go from 4Hi to 4Lo. When you move the lever to 4Lo, shift the truck to reverse and back up about 5-10 feet. You'll find that it goes right in. Remember to never shift any vehicle into 4Lo while rolling.

DearMeadowFarms,

The clunk that you hear when the truck shifts into 4Hi from 2Hi when the rear wheels are spinning is because the front wheels are not going near as fast as the rear wheels are, and when it engages, it slams the front in to try to catch up. It is not good on the 4x4 system, but sometimes it happens. Just try not to do this often. Now to shifting the truck into reverse and it taking a moment, is this in 4x4? If your talking about it only in 4x4, then I have the same thing going on with my truck. I've taken to the mechanic to check it over, and he stated that it is normal and not to worry about it.

Hope this helps......Aaron