so my buddy gave me a pr4 ecu he was going to throw out...i said here give it to me so i can try to figure it out ,maybe something got burnt out on it, i can desolder it, and replace with a new one.....

anyway i plugged the ecu into my car and got the cel to come on but it never went out...i thought that was wierd....opened up the ecu and cant really tell if anything could be burnt out or anything .....what usually goes bad in these obd1 ecu's? if anybody has anything let me know..i would like to try to fix this as a mini project..... thanks in advance
heres a pic hope it helps