I finally get all the little things working on this 91 loyale, and then the 4WD stops working! It's got the pushbutton 5spd manual transmission, so I've managed to check everything up to the two vacuum solenoids near the right front strut tower, the vacuum seems fine out of there (the front solenoid gives vacuum when the switch is on, the rear one when it is off, you can hear a hiss when the button is pressed). There doesn't appear to be any leaks in the hoses up to the transmission, but that's as far as I've got so far in terms of diagnosing. The 4wd did work when I used it a few weeks back, and it sure would be nice to have it work for the winter coming up, anybody have any hints or ideas as to what I should be looking for?

Ben:

 

You're on the right track.

You may have to trace those vaccum lines further back, but it's very likely to be a leak somewhere in the system. Interesting that you hear a "hiss" but haven't yet located the source.

good luck, John

same happened to me, but my leak was real easy to find. all i can suggest is tracing those vac lines back until you find it.

You can check the cable that is operated by the vacuum pods.

 

 

It is located on the pass side of the trans and should move to the back and to the front, shifting a small lever on the side of the trans.

If that is working then you might just have a bad sensor that is not lighting up when it shifts in. or maybe just a broken or disconnected wire to the sensor.

 

Hush