it's entertaining that you know how to troubleshoot the problem, but you have no clue where to start

check:
-brake fluid is in the res (switch in the reservoir when fluid is low)
-ebrake isn't sticking (switch)
-test drive the car and see if the ABS works (sensors)

 

This sounds like the common issue of ABS wheel speed sensors and their wiring harness with 2007/2008 Yaris up to a certain VIN as found in a Toyota TSB here:
T-SB-0120-08

There are two good threads about this issue on YarisWorld
ABS and Brake Warning Light Thread 1
ABS and Brake Warning Light Thread 2

If after checking your brake fluid level and e-brake operation are fine I'd start investigating those sensors

 

Thanks i found out the problem, i drove through a snow strom and a speed or skid control sensor must have got covered with snow. So i Kept it in the garage over night and checked all my fuses and took the battery cable off to reset it. So far so good.

 

VERY common problem this one. Dealers will replace rear ABS speed sensors and wiring looms for $750 or you can spend 30 minutes under the car for free! I did this a while back and no problems still. Behind the rear drums unplug the "only" electrical plug you can see, give it a full clean out with whatever product you favour (I used WD40 then air pressure to dry off). You will need a small screwdriver as its a bugger to seperate the connection. Put it back together and hey presto... ABS again and a fortune saved! I live in the Southern Ontario snowbelt and the sensor isnt positioned well for winter here!

Good Luck

 

I did this a while back and no problems still. Behind the rear drums unplug the "only" electrical plug you can see, give it a full clean out with whatever product you favour (I used WD40 then air pressure to dry off). You will need a small screwdriver as its a bugger to seperate the connection. Put it back together and hey presto.
Good Luck

Has this worked for anyone else?

 

This seems to be an issue with the 07 Yaris. My car has the ABS and the emergency break light on. I am nerves to take it in because of the cost of fixing it and not knowing if it is fixed.

Upset Yaris owner