I HAVE AN 88 ISUZU TROOPER THAT DOES NOT WANT TO BE FIXED. ABOUT A YEAR AGO THE HEAD CRACKED, SO IT GOT REPLACED. AND EVER SINCE THEN NOBODY SEEMS TO KNOW WHAT IS WRONG. THE PROBLEM WITH THE TRUCK IS THAT IT HAS NO SPARK. IT HAS A NEW DISTRIBUTOR, PLUGS, WIRES, COIL, AND HEAD. IT CRANKS, BUT NO SPARK. WHEN I RAN THE SELF DIAGNOSIS TEST IT GAVE ME A CODE THAT SAID,"THE POWER TRANSISTOR CIRCUIT" IS BAD. I DON'T KNOW WHAT THAT IS,LET ALONE WHERE IT'S LOCATED. PLEASE HELP...