I have had this headlight problem with my last toyota and my current 1993 4runner. My low beams work perfectly, and my high beams will only work when I pull back on my headlight switch to pulse them. If I push the headlight switch forward to turn the high beams on constant then the low beams turn off like their supposed to, but the high beams will not turn on. I've replaced the switch cluster in the steering collum with the headlight controls and the blinker and no dice. The high beam fuse under the hood is still good. I dont know where to go from here, if you have dealt with this problem before let me know what it could be and where to defective part may be.

 

Was the replacement parts new or used ? If used the contacts in the switch may need touched up with a emery board. I had to do this on a friends t-100.

 

One page 8 #199 of my build below, I have a fix for this. Probably the little contact behind the clear cover. I just took a nail file and knocked the corrosion off. You can rent a steering wheel puller for free from a parts store.