Blue Vacum Hose

'89, 231, with disconnect front D30.

Coming up from the t-case, up by the back of the valve cover. The green, yellow and blue vacum hoses split from the red. The green, yellow and blue go into a triangle shapped plastic adapter. The yellow and green then go through another harness to run the shift motor on axle. The blue runs from the triangle adpater to what looks to be pressure regulator. WHERE DOES IT GO AFTER THE PRESURE REGULATOR?

Anyone know if I order the second harness, that is between the triangle adapter and hard line, if I'll get the "T" part that runs from the white hose?

Nowhere! Confuesd the hell outta me too.

I just ran out an took a quick look and the yellow and green hook to the hard lines going to the axle then theres a white that hooks to a T and that goes to the axle and switch on the fender. You probably knew all this, but on mine the blue is just sitting there not hooked to anything so no help here sorry

Why are you trying to trace this, 4wd not working?

TORX

From what I recall here's how it goes (I've since ripped all that crap out)..

Red - Source vacuum to TC Switch
Yellow - 4WD
Green - 2WD
Blue - Unused.

The vacuum switch gets it's vacuum from a split junction in the yellow line (by the way, I may have the colors of the lines wrong here, but I nkow blue is right!). One side goes to the blue/green vacuum switch, the other to the shift "motor".

The Green line goes straight to the shift "motor" to pull it out of 4WD.

The Blue line goes to a check valve of sorts and terminates there. I looked all over hell for the other side of that blue line!

GSequoia said:

From what I recall here's how it goes (I've since ripped all that crap out)..

Red - Source vacuum to TC Switch
Yellow - 4WD
Green - 2WD
Blue - Unused.

The vacuum switch gets it's vacuum from a split junction in the yellow line (by the way, I may have the colors of the lines wrong here, but I nkow blue is right!). One side goes to the blue/green vacuum switch, the other to the shift "motor".

The Green line goes straight to the shift "motor" to pull it out of 4WD.

The Blue line goes to a check valve of sorts and terminates there. I looked all over hell for the other side of that blue line!

Click to expand...

So the blue line goes in to the black round check valve and ends? Nothing attaches to the other side of the black round check value?

Any idea if a NEW second part of the harness includes the white hose's "T" connector that one end attaches to the hard line on the fender and the other attaches to a pressure regulator on the passengerside engine compartment?

Thanks!

GSequoia said:

From what I recall here's how it goes (I've since ripped all that crap out)..

Red - Source vacuum to TC Switch
Yellow - 4WD
Green - 2WD
Blue - Unused.

The vacuum switch gets it's vacuum from a split junction in the yellow line (by the way, I may have the colors of the lines wrong here, but I nkow blue is right!). One side goes to the blue/green vacuum switch, the other to the shift "motor".

The Green line goes straight to the shift "motor" to pull it out of 4WD.

The Blue line goes to a check valve of sorts and terminates there. I looked all over hell for the other side of that blue line!

Click to expand...

That sounds right to me I too ripped it all out and slapped a posi lock on there.

TORX

JohnJohn said:

Any idea if a NEW second part of the harness includes the white hose's "T" connector that one end attaches to the hard line on the fender and the other attaches to a pressure regulator on the passengerside engine compartment?

Thanks!

Click to expand...

I've no idea what a new one comes with...

The "pressure regulator" you refer to, is that the small blue/green device about 1" high, cylinder in shape at about 1/2" diameter, with a wire coming out of it? If so that would be your vacuum switch to put your 4WD light on.

Are you having trouble with your system, or just patching up sixteen years of use?

If you are having trouble I'll tell you the trouble spots I found:

The switch in the transfer case. These go out, amazingly they can be gotten cheap from the Help! section of most auto parts store.

Vacuum Blocks. The big rubber guys that the lines go into to, that's where the go from that crappy brittle plastic line to a metal hard line. The rubber gets bad and will not hold vacuum, I bypassed all of thse (there will be two for the short section that the lines become metal, at the RH "frame" rail and one at the shift "motor" itself).

Cracked lines. Those crap plastic lines suck!

If you ahve any questions post up...time for me to go hit the Meet and Greet.

Sequoia

PS - Found any confused wait staff lately? :gag:

TORX said:

Why are you trying to trace this, 4wd not working?[TORX

Click to expand...

As with everything I try to complete...I was replacing my gauge cluster....stick with me here.

I busted the white plastic clip on the gauge end of the speedo cable. After calling the dealer to get a replacement cable orderd. I head out cursing at myself, I pop the hood and begin to pull the cable through the firewall. I get it all pulled through and head down to remove the cabel at the case end. As I pull out the the cable out of the cone it gets caught on the vacum hoses...brittle as they are...three of the four crack and the rest is history. The vacum stuff under the hood is just as brittle and busted a bunch of that stuff just trying to get it all unpluged....

The blue hose is not "unused" but open to the atmosphere so that whichever side of the vacuum diaphragm is switched to "no vacuum" will vent and allow the other to pull. If you think about this it will make sense. The little gadget on the end is just a filter to keep out the bees and spiders.

Matthew Currie said:

The blue hose is not "unused" but open to the atmosphere so that whichever side of the vacuum diaphragm is switched to "no vacuum" will vent and allow the other to pull. If you think about this it will make sense. The little gadget on the end is just a filter to keep out the bees and spiders.

Click to expand...

Learn something new everyday :lecture:

TORX

Matthew Currie said:

The blue hose is not "unused" but open to the atmosphere so that whichever side of the vacuum diaphragm is switched to "no vacuum" will vent and allow the other to pull. If you think about this it will make sense. The little gadget on the end is just a filter to keep out the bees and spiders.

Click to expand...

Thanks for validating my theory Matthew! I figured it out on the phone tonight :cheers:

FEI(for everybodys info)
Those cheep hard brittle pos lines that break waaaaaaay to easily can be spliced with 5/32 gas line hose....and if you wanna you can dab a little rtv sealant around the splices.
The most common breaks are at the firewall,or under the battery tray.
When I first got my 89' I had no 4wd,defrost only got to lookin round under the hood started splicin and Taaaaaa Daaaaaa all of it works.
Now if I could just get the SOB that jacked my AM/FM/CD player to bring it back all would be just fine :laugh3: