4WD Actuation

[Jay P]

My 1988 GMC K1500 has had a problem where 4Hi and 4Lo wouldn't engage. I thought it was my 4WD actuator but... I get under my truck too see my 4WD actuator is completely not plugged in. There are no wires under the truck connecting the transfer case too my front diff seems like. The only thing I can pick up on is a three prong female connector coming from where I think my transfer case shift linkage is. There is a 4WD actuator harness you can buy but I don't see where the harness plugs into on my transfer case.

Some more info on my truck that could factor into my 4WD not working... My truck was originally a 4.3 V6. When the motor blew a 5.7 V8 was swapped in from a 1990 2WD pickup. The engine computer and wiring harness was carried over. Yet the 2WD light on my transfer case still works and the 4WD fuse is still in my fuse box.

I'm considering getting this differential lock kit for my truck hoping it would fix my problem. My question about this is do I need to have any wiring for this too work and will my 4WD light come on?

Anyone on here use or know how to install the Differential cable lock>

https://www.4wheelparts.com/Drivetr...9aKkz8d8QNmTBe77KIjz0hfxhOqA5G0saAltNEALw_wcB

Not my truck... video example of the posi lock.

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[Supercharged111]

If you used the 2wd 5.7 engine harness then I believe you've found your problem. I believe the diff plugs are on the engine harness. This would also explain why nothing is plugged into the t case. How did this go unnoticed during the swap?

 

[Jay P]

If you used the 2wd 5.7 engine harness then I believe you've found your problem. I believe the diff plugs are on the engine harness. This would also explain why nothing is plugged into the t case. How did this go unnoticed during the swap?

I didn't do the swap. Since there are no wires connecting the T-case, would the posi lock help me get working 4WD?

 

[Supercharged111]

That'll get the axle engaged. As long as the t case goes with just the floor shifter then that oughtta do it. I'm guessing the manual t cases only have wires for indication?

 

[Jay P]

That'll get the axle engaged. As long as the t case goes with just the floor shifter then that oughtta do it. I'm guessing the manual t cases only have wires for indication?

Yeah that's what I'm assuming. Wires for the fancy lights to come on.

 

[RustyTruck]

The light for your 4wd comes on when the actuator pushes the linkage in inside your differential. You don't need the actuator for this to happen, and it has nothing to do with your transfer case.

My actuator got caught and ripped out the wires while wheeling. I just unscrewed it and put a 7/8s socket from harbor freight in there between the differential and the actuator for the time being. This turned my 4wd light on. Now everything spins, but it won't be in 4wd until you engage your transfer case.

I looked at the posi-lok, and if I was going to keep my IFS I would get it. The thermal actuator is garbage anyway. Beware, there is a cheap Chinese rip off version of the posi lok, make sure to get the real deal.

Don't know if this helps any...

 

[lubbockguy1979]

I swapped a 91 tcase into a 94 truck. The plugs were different so i just wired the front actuator into a toggle switch. Worked like a champ. That was probably 10yrs or more ago

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[Jay P]

The light for your 4wd comes on when the actuator pushes the linkage in inside your differential. You don't need the actuator for this to happen, and it has nothing to do with your transfer case.

My actuator got caught and ripped out the wires while wheeling. I just unscrewed it and put a 7/8s socket from harbor freight in there between the differential and the actuator for the time being. This turned my 4wd light on. Now everything spins, but it won't be in 4wd until you engage your transfer case.

I looked at the posi-lok, and if I was going to keep my IFS I would get it. The thermal actuator is garbage anyway. Beware, there is a cheap Chinese rip off version of the posi lok, make sure to get the real deal.

Don't know if this helps any...

How did the socket work? Did you just place the socket inside the front diff and bolted the original actuator in after it?

 

[RustyTruck]

How did the socket work? Did you just place the socket inside the front diff and bolted the original actuator in after it?

Sorry I didnt respond, been to busy at work.

Its been working great. I havent had any problems(as of yet). Supposedly drives MPGs down a bit, but I havent checked it yet.

Yes, I unscrewed the actuator, slid the socket in, and put the actuator back in. I jacked one wheel up so it could turn. The way these differentials are set up, it needs to be able to move to engage. Thats why people burn up their 4wd actuators when they turn it on when parked and then dont move.

When I get the chance I will do a short write up with some pics. Ive seen a couple people looking for easy quick fixes(myself included) and it doesnt seem many people know this trick.

 

[brandon2500]

Sorry I didnt respond, been to busy at work.

Its been working great. I havent had any problems(as of yet). Supposedly drives MPGs down a bit, but I havent checked it yet.

Yes, I unscrewed the actuator, slid the socket in, and put the actuator back in. I jacked one wheel up so it could turn. The way these differentials are set up, it needs to be able to move to engage. Thats why people burn up their 4wd actuators when they turn it on when parked and then dont move.

When I get the chance I will do a short write up with some pics. Ive seen a couple people looking for easy quick fixes(myself included) and it doesnt seem many people know this trick.

i would love to see how u made thats work as im having simalar issues with my 92 k2500 i just need my 4x4 to work untill i do the axel swap to something more reliable