I am helping a freind out with a no start/ no spark problem on a 88 Blazer with TBI and external coil HEI. He has injector paulse, dist rotation, and key on power to the pink wire at the coil, but no spark. We have changed the modgual 3 times, the pick up twice, and ing coil once. With the tach disconected and a test light hooked in place we have key on power, but when I crank the engine over the test light dose not paulse. Any ideas would help.