i have the repair manual and have gone thru the step by step diagnostic procedure. it will not fire the coil. have replace the started because it was slowing down, the ignition module was bad so i replaced it along w the coil. i can unplug the 4 wire side of the gm ignition module and the coil will fire. yet the computer throw no codes to read. i found some broken wiring in the wiring harness and replaced it w still no avail. and have replace the small 2 pin harness from the coil to the ignition module also. your help is greatly appreciated. cmp450l 0132 9589 is the rest of the numbers. sorry for the wrong info it is a tier 2 emissions, it does have a trim valve