The old '90 Loyale has turned over 400,000 miles, chassis seems to be getting tired.  Latest problem,  4WD has quit.  Button on shifter no longer causes 4WD to engage.  Dash display does not illuminate.   Haynes manual doesn't even mention this possibility in the electrical section, or anywhere else I can find.

 

Doesn't seem to be a fused circuit, at least not mentioned on the fuse box lid, no coverage in the schematics...

 

HALP!  I really need my 4WD for work..

Teh electrical is probably still working.  The switch activates the solenoids.  The light in the dash won't come on until the trans actually engages 4wd.

 

It's more likely a vacuum issue.

 

Check that the line supplying vacuum to the solenoids is connencted.

 

Solenoids are on the drivers side strut tower, fed vacuum from the resevior on the other side strut tower.

I have a 1988 DL (ie., Loyale) with push button 4wd.  For this vehicle, on the passenger side of the engine compartment there is a vacuum hose coming from the manifold going diagonally up to the passenger-side corner on the fire wall.  In the corner is a small white vacuum canister mounted on the fire wall.  Just make sure that the vacuum hose, via a T-fitting, is connected to this canister.  When my 4wd does not work and is not illuminating on the dash - it is always that the hose is not connected properly. 

Thanks guys.  You nailed it first time, the vacuum line was disconnected, took about 10 seconds to find and fix, when I knew what to look for..  I probably did that myself when I was changing that side halfshaft and wheel bearings, couple of weeks ago..

 

Recently:  Wore out all four tires, replaced with Michelin Defenders.  Hit a buzzard, broke and replaced the windshield.  Broke the clutch cable, stranded in Murphy's, CA for an afternoon.  Replaced the afore mentioned halfshaft and bearings.  Replaced the timeing belt and water pump, re-replaced the water pump with proper part (my bad).

 

To do list.  Replace worn out drum brakes with GL disks & calipers, probably master cyl too.  Replace rear pumkin, making noise.  Will want shocks pretty soon, KYB I reckon... Steering tie rod ends want replacing, too.

 

Been running Shell Rotella T pretty much since I bought this thing, runs 45+ oil anytime off idle.  I check and adjust the oil as needed, daily, an yet sometimes have lifter noise from the right side when cold.