power lock problem
 

i hope someone can help me out here. i have a 2000 4runner and there's a problem with the powerlock. the problem is that it wont lock automatically but it will unlock. i can also lock it manually by pushing it in or using the key. the alarm works fine too. the problem is for all 5 locks. i recently took it to the mechanic to see if they can fix it, seemed to me that it's not really a big deal. at the end of the day the mechanic told me that its a body modulator that needs to be replaced. it also cost heck of a lot. so i told them no and spend 300 buks for nothing. i need help here. i can just manually lock all the doors forever if its gonna cost me arm and a leg to fix it. does anyone have any idea? is there someway that I can fix it myself???

wait, i need clarification.

you can push the arm button, and they will all lock? But it won't lock when you push the lock button inside the cabin?

no, i have to individually lock them all. so to lock the car i have to either individually push down the lock or lock them with the key. it wont lock when i press the powerlock switch or through the remote.

Perhaps its a sign that the remote batteries are dying?

nope, not the remote b/c i can't lock it by pressing the powerlock switch. i checked the fuse on the fuse box by the driver side but seems to me they're all fine. any other ideas???