Alright folks, I'm about 6 minutes away from burning my k1500 to the ground and buying an electric car.

I have been having problems with the thermal linear actuator for the front diff on my 92 k1500. My transfer case engages the front driveshaft no problem. When the vehicle is cold, the thermal actuator engages the front diff no problem. When the vehicle is warm (operating temp) the thermal actuator no longer engages the front diff. The fuse panel shows power  on the 4wd fuse, and the fuse is good.

Today I installed a new thermal actuator (upon the advice of my mechanic). NO change in the problem and I am out $120. I cannot afford a "posi-lok" cable, nor can I afford the drop in MPG by putting in a solid bar, but i need my damn 4x4 becasue duck hunting starts soon.

I used a test light an and found that there was no power going to the new actuator with the t-case in 4wd.  

What I need to know is some further details to the location  of relay's and switches in this system as I belive i have a heat induced electrical short somehwhere. I imagine there must be a wiring harness from the t-case to tell the front diff to engage, but i have yet to find it.

The internet seems devoid of any info. HELP ME!!!!!     

I had a thought in the last 1/2 hour (rare occurrence). Does anyone see a problem with me running the new actuator off a keyed 12V source with a toggle switch in the dash??? (with an in-line 25amp fuse as well). This would allow 2 low as well! Plus the indicator light on the t-case would function the same, preventing me from leaving the front diff engaged in 2HI.

Comments/Concerns?

Well i went ahead and did it, and it works amazing!

I would like to claim to be the first try this, but someone must have done this before.

It works perfect so far, cold, havent had a chance to bring the  truck up to temp and try it (which was alot of the prob before).

I'll see if this is the solution. And i get 2Lo out of the deal!

Good idea! I don't know of any one that has bypassed the electrical side of the actuator. If it keeps failing on you, I built a "copy" of the posi-loc system for less than $50. The most expensive part was the locking cable push-pull cable (about $35 from O'Reilly or Napa Auto parts) the rest was common odds and ends from the hardware store.

I was gonna do that too (build a copy of posi-lok) but the open end of the cable would probably disagree with the copius amounts of salt the province isnsists on rotting my truck with all in the name of traction (for yuppies who wont buy winter tires).

I am lovin that switch in my dash now. I am impressed with my own ingenuity...had been in a "brain slump" for quite some time now...

I used a piece of 5/16" smooth rod, threaded with a clevis on one end to pass through  the axle housing to the central axle disconnect. I used parts of the original actuator housing, and some washers, grommets, and O-rings to seal it up, and it's been working great for 3 years.  I might post a picture, but I'm not sure that the Posi-lock guys would appreciate it...  

I could see why they might not like it!. Sounds like you built a better unit anyhow.

So far my switch is operating problem free. I do have some concerns on how much juice that the actuator may be drawing from IGN+ source. I am considering rewiring and using a proper relay.

Any ideas on how many amps that the actuator might draw?

Hey my name is dennis and i've got a 92 with 330,000 on her and have the EXACT SAME D*MN PROBLEM !!! I took the actuator out and hooked it up too the battery to test.  It worked, but slow, real slow.  And that thing got so hot even when held to power for several seconds that I almost couldnt hold it.  So what i'm thinking from what u put down, is that the slow means its workin, right? My question is did u test yours, and if so, did it move slow?  And does yours get real hot when engaged for a long time?  I'm thinking if i wire it up to 12v somewheres that its gonna fry something.  Let me know.  I can use all the help i can get. Thanks  bignmuddy  

Sorry i forgot that thee ol battery has  700 some amps and the actuator probably doesnt need that to engage.(that would explain the so hot i cant touch thing.)   Do u guys no what amps that takes to engage?  Well i'm makeing some progress, i think.....thanks again  

is it the vacuum switch on top of the transfer case? this is the only other thing i would think!!!!  

The actuator is only going to draw the amount of current it needs. To find out what the current draw is you can either connect an ammeter inline and measure it, or start stepping down in fuse size until one blows.
And you defenitely want to rewire using a relay.