4x4 Front Actuator Change...

spoolin4 · January 15, 2011

Well, seeing my 4x4 used to engage when I bought the truck (4 months ago or so) then it worked off-and-on and now it doesn't, I've decided that the culprit must be the front diff actuator seeing there's no "service 4x4" light.

Anyways, I managed to pick one up for $100 cash from a friend who works at a parts store and when I went to remove the OEM actuator, it will NOT budge. I even had the biggest guy at my shop give it a shot and he couldn't even move it.

Basically my question is; Can I use little heat or what are other things can I try? This is a plastic component so the last thing I need is for it to snap and be stuck in the transfer case.

I'm looking at the new one and it doesn't seem to be reversed thread either, so I'm obviously loosening it the proper way...

Thanks!

Feel like a noob seeing it's just a "thread-on" part and we can't get it off...

8.1HD/ALLISON · January 15, 2011

If you are changing the front diff actuator and can't get it to move, it shouldn't hurt to apply a little heat to the housing where it threads in. Just don't go overboard with the torch.

spoolin4 · January 15, 2011

If you are changing the front diff actuator and can't get it to move, it shouldn't hurt to apply a little heat to the housing where it threads in. Just don't go overboard with the torch.

I was going to throw some heat at it, but just wasn't sure seeing the actuator's plastic.

I'll have to give it a try.

Thanks.

spoolin4 · January 16, 2011

Well a propane torche didn't do a thing. This actuator is seized on there good!

Going to have to use the oxy-acetelyn torches at work tomorrow and see...

I can break it off, but the threads will still be in the housing which I need them out to put the new actuator on, so ya, that won't work, lol.

spoolin4 · January 22, 2011

Okay, so I got the old actuator off, put the new one one and the 4x4 has worked awsome all week.

Now, for some reason, it's doing it again... No 4x4, no dummy lights, when I press the button to change modes the light/switch does everything right, but in auto 4wd and 4hi/lo the trucks still in 2wd...

2005 GMC Sierra 1500 5.3l

I'm getting really pissed off about this seeing I bought the truck specifically for 4x4 and GM was always the brand I would want for a truck...

Matt_ · January 22, 2011

Time to get out a DVOM and check the voltage going to that front actuator. Did you verify that the old one wasn't working by applying voltage?

How are you testing to see if you're in 4x4 or not?

spoolin4 · January 22, 2011

Time to get out a DVOM and check the voltage going to that front actuator. Did you verify that the old one wasn't working by applying voltage?

How are you testing to see if you're in 4x4 or not?

How much voltage should be going to the actuator? Should it be constant or only when different buttons are pressed?

As for testing it, either floor it (rear end kicks out) and jacking it up and spinning the free-spinning front wheels when in 4x4.

Who knows.... maybe it'll work today, lol...

If it's not getting proper voltage, could it possibly be the switch even though the lights go on and everything works as normal, besides not having 4x4 for that spurt of driving last night?

spoolin4 · January 22, 2011

Well, guess what?

Just went to do groceries and 4x4 is working....

This truck has a mind of its own!

jro909 · January 22, 2011

why not allow a qualified mechanic to diagnose the problem

spoolin4 · January 22, 2011

why not allow a qualified mechanic to diagnose the problem

Because I am a lisenced autobody repairer/painter and I will NEVER pay ridiculous diagnostic fees that I can do myself.

I've also built a 420 whp Honda prelude drag car(11.6 e/t) and race dirt oval. By saying that, I'm not a noob when it comes to mechanical repair.

This is just my first GM truck so I'm still learning the flaws and common errors with these things. I'm not the first person in my area with 4x4 issues, just everyone I've discussed this issue with, share different symptoms.

[email protected] · January 22, 2011

When my 4x4 worked at random, years and years ago, it was the switch in the dash, but many people have the t-case actuator go out, never heard of a problem with the front diff actuator though.

spoolin4 · January 22, 2011

When my 4x4 worked at random, years and years ago, it was the switch in the dash, but many people have the t-case actuator go out, never heard of a problem with the front diff actuator though.

I'm gonna get a hold of another switch and see if the 4x4 will stay working longer than a week.

I can't see the actuator freezing up, I mean, I live in Canada and you would think trucks would not have week items like this involving the infamous 4x4...

Matt_ · January 22, 2011

faulty switches or motors will normally cause a "service 4x4" problem. front actuators going bad are actually a very common occurrence on GM vehicles.

With 4x4 engaged there should be a constant 12V going to the front actuator. I'd start there.

Also keep in mind that the front diff is open... so if one tire is on ice and you punch it, it's going to feel like you have 2wd. Your 4x4 might be working perfectly fine...

When you jacked the front off the ground to "free spin" the front wheels, what exactly did they do AND did you try spinning the driveshaft?