Anybody have an answer for this problem for a 2nd Gen 4 runner?

My 4wd indicator light on the dash panel doesn't stay on. When I manually engage the transmission to H4, the ADD(?) relay on the dash clicks a few times, then the light flickers and goes out. I'm not sure if the 4wd drive is engaged or not.
The linkage to the transfer case moves when the shift lever is positioned in H4. So does that mean the 4wd is working?
How can I check if the 4wd is engaging? I hope it is just a little relay...
BTW, I recently had the motor replaced, the vacumm hoses look to be in the correct spots.

1990 4 runner -

 

I sorta had that same problem with my 3rd gen except the light wouldn't come on at all. The front driveshaft rotated for mine too. But when I went up a dirt hill, the guys watching me noticed that my front wheels weren't spinning. I thought I was in 4wd, but I wasn't.

So to answer your question, I don't think you are. Good way to check would to be go to some sandy area and have somebody watch you.

Also are you trying to shift to 4wd on the fly? Or when you're parked? Cuz mine won't shift on the fly anymore, just in park.

 

Put the shifter in the H4 position, then put it in park. Get out and try to turn your front drive shaft by hand, if 4wd is engaged it will not turn. If its in 2wd, the front drive shaft should turn freely.

 

I had the same exact problem after i had my engine rebuilt, relay clicked, and no light came on. For me, it was the vacuum hoses. Might not hurt to give them another look.

 

Where are the 4wd vacuum hoses for a 1990 4 runner?
I found the blue filter hose, but I'm not sure where it should start and end.

Is this the only vacuum hose for the 4wd system?

 

Both vacuum lines are on the front axle housing. Remove both and start your engine. One of those hoses should suck. As soon as you put it in 4WD the other hose should start to suck.
If not, your ADD control system is malfunctioning.
If they do, your ADD system is mechanically failing inside the axle.
You can test it by running a long vacuum hose and connect it to either one of the pipes from the ADD housing on the front axle.
You should hear the system engage and disengage.
O, both vacuum solenoids are on the right fender wall, just follow the lines from the front axle. They run just below your power steering hoses.

 

This might be totally unrelated, but when I first got my 92, I had the same problem. Luckily I new the previous owner and he said that he shifted into 4WD maybe 5 times in the 10 years he owned the truck.

Long story short, I just put the shifter in 4WD and drove around for about 20 minutes, being careful not to take sharp curves, etc. It blinked and turned off for several minutes, and finally it stayed on.

It's worth a shot...

 

thanks for the tips...
I'll try these tests today. I hope the engine rebuilder didn't screw up. It's been almost a year since I had the work completed. My first test will be to jack up all four wheels and see if they spin in 4WD. Then, I'll try to tackle the vacuum hose test...
I'll post the results soon.