'88 RX AWD, 4WD doesn't engage....

[SmashedGlass]

...tested out the 4WD on my RX this morning and there is no noticeable difference with the switch in the on position; I drove her in a tight circle with it on and with it off and got no drag, pop, shudder, etc. Also as I said awhile back I get no dash indicator for 4x4 though I do get the 'Lo' indicator when I shift from AWD Hi to Lo. So I'm guessing it doesn't engage when switched. I do hear a momentary hiss of air when I work the switch (perhaps a second or so) which tells me the switch itself works, but where does it go from there? I can't find any clear information in either my Chilton's or Haynes relating to the full-time AWD & 4WD system that is on the RX's and GL-10's. Help!

[Gloyale]

Are you talking abou thte Difflock switch? You shouldn't hear hissing. Perhaps you're vaccum lines form the solenoids to the actuator are disconnected? or maybe the actuator has a leak? Good news is that the actuator and solenoids are the same as the PT4wd Actautor. It just connects to a different lever on the trans. you can replace it with the actuator from any PT4wd.

[SmashedGlass]

Are you talking abou thte Difflock switch? You shouldn't hear hissing. Perhaps you're vaccum lines form the solenoids to the actuator are disconnected? or maybe the actuator has a leak? Good news is that the actuator and solenoids are the same as the PT4wd Actautor. It just connects to a different lever on the trans. you can replace it with the actuator from any PT4wd.

 

okay, so I shouldn't even get a momentary sound of air...hmm. but where is the actuator located?

[Gloyale]

It's on top drivers side of transmission. It's a big Vac diaphrahm with a cable coming out of one end. Follow the 2 vaccum lines form the solenoid down to the trans. Solenoids are right behind drivers side strut tower.

 

I need to clarify. This is a Fulltime 4wd right? you won't get a 4wd indicator on the dash. You'll get a *diff lock* light if its working. The Hi/Lo is a totally seperate portion of the trans, and should be working regardless of the difflock. Note that even without the diff locked you have AWD via the center diff. But if one wheel begins to slip you will lose power transfer. Do you're heater controls work? can you get air from the Defrost/vent/floor? or just the vent? What I'm getting at is that you may have a vaccum hose disconnected or crimped. Check all theVac lines espescially the one going to the reserve tank and the one going to the solenoids.

[Skip]

By chance are your heater controls stuck in one position?

 

 

The solenoids (x2) are located infront of the wiper motor.

 

The diff lock switch controls which solenoid passes vacuum.

 

This vacuum source is provided via the vacuum canister located behind the pass side strut tower.

 

This same canister provides the vacuum to operate the heater controls.

 

Hope this helps.

 

(sorry for the double info post G, you just type faster than I)

[joostvdw]

something else to add, if the central diff lock hasn't been used for a while, it might be somewhat hard to engage and may not engage at all if not driving perfectly straight

 

lubing the cable is also a good thing

[SmashedGlass]

Yes, everything else works fine (i.e. heater, defrost, even the frickin ICE cold and, I suspect, R12-filled a/c system); the only thing not working is the diff lock. And that's what I meant by not getting an indicator-the diff locked indicator on the dash. Thanks for the input guys, I'll get around to checking it when Mr. Blazing Orb isn't out trying to incinerate everyone here in Colorado. I'm just concerned about not having it operable because, though I have full-time AWD, I may want to do some light wheeling up in the mountains and having true 4x4 would be very nice....plus I like everything to work on my cars, regardless of how often or not I may use it.