4WD to 2WD Integrated Vacuum Switch - Jeep Wrangler Forum

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Old 01-18-2011, 05:07 PM   #1
Join Date: Oct 2010
Posts: 6
Jeepentg is on a distinguished road
4WD to 2WD Integrated Vacuum Switch


01 Fuel Selector Valve – “Borg Warner” – Part Number FSV1 – O’Reilly Auto Parts
02 Fuel Filter – “Maxpower” – Part Number 334282 – Advance Auto Parts
03 Two-Way Check Valve, 1/4”x3/16”x3/16”– “Dorman” – Part Number 47150 – Pep Boys Auto Parts
04 (2) Vacuum Connectors, 1/8”x1/4” – “Vacu-Tite” – Part Number 47302 – Pep Boys Auto Parts
05 (2) Vacuum Tee Connectors, 3/16”x1/4”x3/16” – “Vacu-Tite” – Part Number 47337 – Pep Boys Auto Parts
06 1/4” I.D. Cap – “Vacu-Tite” – Pep Boys Auto Parts
07 15 Amp Push/ Pull Switch – “Dorman” – Part Number 85933 – Pep Boys Auto Parts
08 1 Amp Inline Fuse – “Pep Boys Auto Parts”
09 16 – 18 Gauge Wire – “Pep Boys Auto Parts”
10 6’ of 5/32” I.D. Vacuum Line – “Advance Auto Parts”
11 5’ of 3/32” I.D. Vacuum Line – “Advance Auto Parts”
12 1’ of 1/4” I.D. Fuel Line – “Advance Auto Parts”
13 Zip Ties
14 Wire Conduit
15 (2) each - 1/4”x20x1/2” Bolts, Nuts, and Lock-Washers


Before you start, make sure you have all you parts on the list.
Cut the 5/32” I.D. vacuum line into, (2) two and a half foot lengths, leaving a one foot piece.
Cut the 3/32” I.D. vacuum line into, (2) two foot lengths, leaving a one foot piece. Use the remaining piece to cut your desired length to connect the 4wd vacuum tee to the two-way check valve, and from the two-way check valve to the fuel filter.
Cut the 1/4” I.D. fuel line into, (3) one and a half inch lengths, leaving a three inch piece.
Wrap a piece of electrical tape around the fuel filter making sure you don’t cover the top.
Plug the large port on the two-way check valve.
Mount the fuel selector valve on the inner passenger side fender-well just below where the factory scissor jack is located. There should be one hole already supplied. Bolt it down. Now using a 1/4” drill bit, drill out your second hole and bolt it down. (The fuel selector valve is now grounded. And no, not like when you’re bad.
Make sure you are in two wheel drive, parked on level ground, with e-brake on.
Fine tune “cut” your desired length of the 5/32” I.D. vacuum lines leading to you axle shift motor. (Keeping in mind you’ll want extra for wheel travel).
Un-plug the factory two port vacuum connector and plug in the new lines.
Fine tune “cut” your desired length of the 3/32” I.D. vacuum lines that you will be slipping over the two hard plastic supply lines coming from the transfer-case switch, accessible under the battery tray and possibly inside black wire conduit. The best spot would be after the “Y” from the main conduit. There will be two plastic lines going upward that lead to the one-way check valve and the air filter vent. The other two plastic lines head along the inner fender-well to the vacuum axle shift motor. They are the 2wd and 4wd supply lines. “Cut” those two approximately four inches past the “Y”. This will be your “Integration Points”. Plug them in.
Organize all the vacuum lines as you see fit with wire ties and wire conduit. I left my factory vacuum lines mounted and plugged on both ends for a redundancy, just in case.
Locate a mounting spot for your 15 amp switch. I found it handy to zip tie it to my four wheel drive lever just below the knob.
Run your wire(s), including your 1 amp inline fuse to the 12 volt post on the fuel selector valve.
Test – when you turn on your switch you should hear a little “thud” come from the fuel selector valve. Good, now turn it off.
Time for a test drive. If you’re running an “open axle” you’ll know its working while in low range and in a sharp turn, your front end doesn’t jump around. You know what I’m talking about. If you’re running an “auto locker” you’ll know its working while in high or low range, giving it a little gas, and it pulls hard to the right. (Hang on to the steering wheel). To put things back to your normal, simply turn off your switch.

Notes: This is intended for the use on a '91 - '95 YJ factory Dana 30 or any Dana 30 with an intermediate axle shaft, open or with an auto locker. The items within the red box are what is covered in this thread as "integrated" I’ve tested this in 10 degree weather, through snow, ice, and water crossings with no issues what so ever. I hope you enjoy this as much as I have. The most expensive part will be the fuel selector valve at 40 dollars. This may also be used to by-pass the transfer-case switch. Make sure your system is working properly before installing. Included below are two printable diagrams to help you along. ***ENJOY***

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4wd transfer case switch , 4wd vacuum lines , posi-lok

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