An electrical schematic will help you a ton.You can probably get one from this forum! I Would start at the coil connection. a simple volt test wiyh the key in run.I think its a red\white wire. Given 12+vdc,move on to signal from icu.I would test with low impedance test light.Mine is a snap on,I would think anyone would do.Anyways, ground the test light,probe the signal wire connection and crank.The test light should light up and flash.If it starts, you can test your light on a coil that is firing so you know what you should be seeing.When its running probe the red\white again,Your test light should be on steady.If Your light is real dimn,You may have amperage problem.If You dont have one or both,You need to trace the wire back until you find a break or bad connection.That won't be much fun however.I have a 85 also and those wires have lost some flexibility.You can also test for volt drop in the power wire.Hook Your volt meter up to batt. positive and probe red\wht. at coil with key on and started. Zero reading would be the best.Any voltage shown, would be the volt drop in that circut. If I found I was missing either,I would bypass the wire with a jumper wire and see if i get spark.If that does it,run a new wire or fillet the harness. BTW,Does the tach work? I see one signal wire supplies the v boost contol,fuel pump relay and the tach.Not sure if thats Your dead cyl. or not.The three other signal wires run direct from icu to coil. Hope this helps.Good luck!
