Hello VPN:
well, its been my experience, and I'm not a expert, but my 95 Montero has a vacuum assist to help it engage the hubs in 4WD. I think if vacuum is low, or not much vacuum at all, the indicator, flashes. I see this when its very cold, here in Virginia, like 15? Fahrenheit. After the engine gets a little oil worked up in it, if you tap the accelerator just a bit to race the engine up to 2000 RPM and drop it quickly,that deceleration with the butterfly valve closing in the throttle body, will cause the motor to draw a vacuum, and your indicator should go out. IF you have good vacuum hoses and no leaks. There is a little 'can' lack of a better name, down there near the front axel, that has a little vacuum line running to it, I suspect its a vacuum reservoir. make sure there is not a rusted hole in the can, and the line is still connected to it. If you have your oil changed at a dealer or quicklube, check the 'can' reservoir to make sure the line is still there connected and the monkeys didn't knock it off.
When its cold, I have noticed mine flash for a 12 or 15 seconds in the mornings, especially if I haven't started it for a few days. But when vacuum is created it goes away.
ABS, I don't know. I need a IAC motor for my Montero. Rock auto was sold out last week. I would keep your Montero if I were you. They don't make'em like this anymore.
hope this helps
Rob