4x4 actuator upgrade

[Michaeljp86]

How do you take it out of low do you have to put the trans into N? It would be kick ass if you could just put it back in high, then it would be like having a 2 speed rear end.

 

[SnowDrift]

I'd think you would treat it just as if it was 4LO and put the transmission in neutral before pulling the lever back to HI.

 

[Extremesounds13]

I know this thread is old but here is my problem. I just did a cummins swap in my truck and now that I am done and driving the truck I decide to hook up the speedo and 4x4 cause I had not done them yet. I some how managed to loose my front axle wiring harness in the project so I grabbed one from the junk yard and plugged it all in and no 4x4. So here is what I think happened, before the swap my 4x4 ALWAYS engaged super fast no waiting at all so I think at some point someone put the electric actuator in. So now I have the good actuator but I have just a regular wiring harness, so can and where do I get the right harness to make my actuator engage? And is there a way to tell for sure which actuator is in the truck?

 

[great white]

The thermal actuator is small, not much is visible outside the diff at all. The new design is essentially a stepper motor and is quite large outside the axle housing.

The TLA next to the posilock aftermarket piece. The "dirty" part of the TLA is all you see when installed:

Solenoid/motor style (98 and up):

 

[Big T]

I have Posi Lok NIB that I bought for my '95 Suburban. I was finally able to get the electric actuator conversion to work (key is to splice into the brown wire below the plug at the firewall by the fuel filter) and I prefer the electric. I'll let it go for $150 plus shipping. PM me if interested.

 

[Matt Bachand]

I have the quite large 'big boy' style on my 97 factory. Not sure if it because I also have the borg warner T/C. It works flawlessly, I need to be rolling about 2-5 mph and can hear the teeth 'grind' a tad before it engages. I use it often as I do most of my plowing in 2wd, unless I think I may need 4wd. As always, the key is to have it in 4wd BEFORE you need it.

 

[great white]

I have the quite large 'big boy' style on my 97 factory. Not sure if it because I also have the borg warner T/C. It works flawlessly, I need to be rolling about 2-5 mph and can hear the teeth 'grind' a tad before it engages. I use it often as I do most of my plowing in 2wd, unless I think I may need 4wd. As always, the key is to have it in 4wd BEFORE you need it.

Really? Grinding?

My 98 goes in and out without a single word of protest. At a standstill or rolling...

 

[Matt Bachand]

Really? Grinding?

My 98 goes in and out without a single word of protest. At a standstill or rolling...

More of a meshing, not a bad grind like trying to powershift a manual at the wrong speed, but can hear teeth rotation until it grabs. I think It will engage from standstill, and the second I'm rolling its in, but I go to a rolling almost stop, and can hear/feel a few teeth rotation (5-6) before engagement.

Its not a bad sound, just a normal sound I thought. None-the-less, defanately a sound. Perhaps something is worn (what else is new).. been doing it this way since 85k when I bought it. Now has 140k, and does it the exact same way.

The 4x4 picture on the floor shifter wont light up until that 'grind' noise and engagement procedure is over. And only then is my front axle engaged.

I also like to roll backwards a little bit when disengaging to assure dis-engagement. Sometimes I feel like front still engaged before I stop and roll back to relieve front pressure.

But I don't Off-Road, the only time I use 4x4 is plowing, so I'm constantly stopping, moving slowly, and backing up. I just make it part of my routine and its a seemless transition if timed right.

Perhaps I'm overly sensitive to noises, or perhaps its more of a feel than a noise, or perhaps something is wrong, but It has never not engaged or disengaged once, and it gets a huge workout in the winter time, and only once or twice in between seasons just to keep things from freezing up.

 

[great white]

My 89 was thermal, my 98 is servo.

Night and day difference. Can't even say how great it is.

If you want to keep it without the hassle of yanking the front diff into engagement every time you shift to 4x4, I highly recommend converting to the later model servo actuator.

Of course, you could just leave a posi lok engaged all the time I guess....

 

[Michaeljp86]

My 89 was thermal, my 98 is servo.

Night and day difference. Can't even say how great it is.

If you want to keep it without the hassle of yanking the front diff into engagement every time you shift to 4x4, I highly recommend converting to the later model servo actuator.

Of course, you could just leave a posi lok engaged all the time I guess....

Im surprised your 89 is still going, my dads gave out a long time ago. I wonder how well that thermal gizmo worked when it was new.

 

[jrsavoie]

POur 98 has to move for the 4x4 to engage. I've been stuck a few times because it would not engage. Usually in 1/2" of snow or a little bit of ice. As soon as it moves a little it engages. It's always really pissed me off to get stuck and know I could get out if the front wheels were turning.

I wonder what's up with our 98 not engaging at a stop. We get pulled a few feet and the 4 wheel drive engages and all is well.

 

[jrsavoie]

I ordered a new OEM actuator GM part number 26060073 off Ebay for $76.50 and the harness update GM part 88959465 from oehq.com for about $53.

 

[great white]

My 98 engages as soon as I hit the dash button.

No muss, no fuss.

Just immediate forward traction.

 

[jrsavoie]

I ordered a new OEM actuator GM part number 26060073 off Ebay for $76.50 and the harness update GM part 88959465 from oehq.com for about $53.

For the 1994 K3500

Are there any explicit installation instructions someplace?

I've done the job before on the 95 Tahoe but it has been quite a while.

Thanks
Jeff

 

[Big T]

It's pretty simple to install the actuator as it just scews in. The new harness plugs into the old, but there is a 3rd brown wire that must be spliced into the brown coming from or going to the switch on the transfer case. Instructions with the harness will tell you to splice it there at the switch. Gearheads on another site advised to splice into brown where it runs alongside the transmission tunnel in the cab as that keeps the splice out of the elements. I tried splicing there and had nothing but problems. I finally spliced into the brown on the plug behind the fuel filter on the transmission side of the plug. Your only looking to splice into a power source that's on when the ignition is on. Never had a problem since.

 

[jrsavoie]

I assume you use some pipe dope on the threads?

It looked as if some of the new units I saw had sealant on them from the manufacturer. The OEM I bought does not.

 

[Big T]

Teflon tape, mine came with that on it. Screw it in all the way to the bottom, which should come naturally.

 

[NVW]

Teflon tape, mine came with that on it. Screw it in all the way to the bottom, which should come naturally.

ROFL

 

[dms4x4]

The thermal actuator is small, not much is visible outside the diff at all. The new design is essentially a stepper motor and is quite large outside the axle housing.

The TLA next to the posilock aftermarket piece. The "dirty" part of the TLA is all you see when installed:

Solenoid/motor style (98 and up):

That was an excellent post (with the picture). Thanks.

It takes my actuator between 10-11 seconds to engage. Is this about right?

 

[great white]

That was an excellent post (with the picture). Thanks.

It takes my actuator between 10-11 seconds to engage. Is this about right?

Meh, seems a bit long.

With a TLA, if it engages at all it's working. Ambient temps effect it with engagement.

11 seconds probably indicates a very old one and that's always a "hit or miss" situation...