a friend of mine brought over two Suzuki Swift ECU's, and reportedly told me that Suzi wanted 1300 for a new one from factory.
So he came to my house, i cracked it open. it turned out to be a 1/2 watt 100 ohm resistor or so that was chipped and exposed the ceramic leads inside. I promptly unsoldered it. and popped a new one in.
wouldn't you know.... it worked!
so basically.
1300 dollar ECU, or.... 20 cent resistor? hmmmm.
he took me out for wings. im still waiting for the payback of 1280 dollar in repair fees .
LOL j/k.
there are multiple ways of checking circuits. If you find the schematics for each individual IC (chip = Integrated Circuit) that you can find on the board, you can most often check what the voltage/resistance/current at each pin is supposed to be, and sometimes they come with a cross examination diagram that tells you what reading you should yield if you were to test each input/output by using a digital multimeter across two pins (dont use analog, theyre gonna drive you crazy).
I recently repaired a megasquirt with a dead processor.
the processor was replaced, but then the computer couldnt see the device when i hooked it up. so i checked the trouble shooting guide and it told me that the RS232 (serial connection circuit chip) was supposed to show 5 volts across two pins. upon inspection, it was about 0.01 volts.
$3.50 later, the board was up and running again =)
i hope that sorta makes you feel a bit better about your broken ECU. often times they can be repaired instead of replaced.