|Posted: September 05 2008 at 18:51 | IP Logged
I've never had a problem with Mercruiser's Thunderbolt Ign system. I would go along with the Master Mechanic on that. Whether distributor mounted or Manifold mounted, the wiring for these modules are the same. Differance being only where they're mounted.
By the book here's the connections:
Purple wire coming out of #5 pin on the main harness is the 'I' from the Ing. switch.
Thru the main engine harness, Purple #5 connects to the Positive side of the coil, then continues on to the Ign. Module. Make sure you have Positive 12vdc voltage at the coil and ign module (use a pin to penetrate the insulation and an alagator clipped to the voltmeter) to see voltage there when the Ign switch is on in the 'I' position.
wht/red and white/green wires (rotor sensor) coming out of the side of the distributor and go to the IGN module.
Gray wire out of the module goes to the Negitive side of the coil.
Black lead out of the module is ground.
Carefully check the condition of the connector and its pins if your unit is the Distributor mounted type- they can get bent out of alignment.
I never give up until I'm positive about the Ignition voltage getting to the coil and the module. Then I move on- possibly the rotor sensor.
Roy & Laurie, S.F. Bay Area
'83 280, hardtop, single 305