Hey guys I decided to do a DIY write up on locking your front differential to and Electric locking system.

Let’s start off how it works. Well 1st you engage your 4wd Either to HI or LO range. Then you Flip the switch and that will activate your solenoid. The Solenoid will feed vacuum to your actuator. Wallah your front end is locked.

Things you will need.

Switch for your cab
Wire to run the electrical
EGR vacuum solenoid
Pigtail for the solenoid

these solenoids can be found on early Chevy 350 motors and also 2nd gen blazers with an 236 transfer case.
I Found the solenoid on rock auto under 1988 Gmc k2500. These solenoids can be found on many other makes and models but this is the one I used.

The pigtail depends on what you get your solenoid off of. The Solenoid off a k2500 would use this pigtail.


Here Is a picture of the solenoid off an k2500.



Here are the steps for installing and preparing for this system.

Step 1: Crawl under your vehicle and locate your transfer case vacuum switch. You would have to disconnect the 2 smaller hoses and plug the 2 ports where the hoses connect too.

What I did was left some vacuum line and plugged the line with a small bolt.

The 3rd line (large one) is your transfer case vent. That is the only line you won’t touch.

Step 2: Route your vacuum lines into the engine bay. The 2 lines run up your bell housing and come up by the distributor. Gently pull the lines up while someone feeds the bottom end up to you.

Once you have both lines into your engine bay you can figure out where you want to mount your solenoid. Once you find a spot for your solenoid run the lines to the solenoid. On the solenoid you will have a Vacuum supply port and a port where you need the vacuum to go.
Here is a diagram I made. This only covers the solenoid off the K2500 solenoid. I’m sure the others act the same.

Hook up the lines like the diagram shows and then do the electrical.
The electrical is very simple. It’s just like wiring a fog light but with no relay.

I did not add a fuse but if you would like one. It’s possible to add one.
Once all the wiring is done take your truck for a spin in 4x4 and see if it works. You will feel tension when turning on dirt. I would not recommend doing this on dry pavement.


Here is a picture of my solenoid location


The System works really good and I hope you enjoy it. I know i will.
A good thing about this system is just in case it fails you can jump the vac lines and get out of your sticky situation your in.

Admins/Mods Please feel free to change any thing that is needed to avoid confusion. Thank you.

 

Nice setup and great write up!! I love the thinking outside the box man.

 

Thanks for the right up bud, I plan on doing this mod when I swap in a blazer front diff, I'll just need to snag the diaphram thinger majig & the bracket for it under the battery.

 

Thanks guys Glad the write up is not confusing. Gotta admit It came out better then I thought.

 

i kinda like the being able to jump it encase it doesnt work. i got so fed up with one i had i just ran a valve inside the truck i could just turn the valve to work

 

I agree this system gives you the option to jump the lines god for bit the solenoid fails. Just need to buy a vac coupler from the auto parts.

 

This will work for a 2nd gen right? And what do you mean by jump the lines?

 

yes this will work on 2nd gens. Just In case the solenoid fails you get both vac lines and connect them together with a vac fitting... This will lock your diff till you can swap a new solenoid in. I dont think these solenoids go out this easy but its a possibility.

 

awsome write up another idea i never would of thought of as i was planning on doing the pull cable style instead i like the electonic idea better and there isnt much modifacation needed.

 

Well I ordered the part but not sure if my vacuum hoses are hooked up correctly. My hvac doesn't work right and I can't find a place that shows the vacuum diagram for the 4x4 under the hood I just found the vacuum line that goes to the resoivor with a screw in it.