The coil tested bad on my 93 XLH1200 so I bought a new one. When I pulled the old one, there were four wires attached to the primary terminals. two white wires, a blue wire and a pink.
The wireing diagram in the factory service manual shows four wires as well. Two whites, and two pinks, NO BLUE wire. One pink goes to the tach, one pink goes to the ignition module, one white goes to the stop/start switches and one white goes to the ignition module. There is simply NO blue wire shown in the diagram, and nothing should wire directly to the coil except for the tach.
A little investigation shows that one of the white wires and the blue wire run directly to the timing pickup sensor. HUH??? According to the wiring diagram, there should be THREE wires coming from the sensor, a Red, Green and Black/White and they should go to the ignition module, but my sensor has two wires, a blue and a white and they go directly to the coil.
This makes no sense at all. I don't even know where to begin.
The timing cover has never been off as near as I can tell. The rivets were unmolested, and the gasket looked original. That, and the level of corrosion lead me to believe it is the original sensor, but as you can see, there are two wires (blue and white) not three, and they go direcly to the coil.
I traced (continuity check) the two pink wires from the coil back to the tachometer and the ignition module harness as they should be. There were no breaks in the wiring, so no reason that I can see to replace/bypass them. I also traced the white wires from the coil back to the stop/start switch and the ignition module; again, no breaks, no reason to replace/bypass them.
The only thing I can think of is that at some time in the 23 year history of the bike, the timing sensor was replaced with an after market sensor that only has two wires and to make that work, the wires from the coil to the ignition module were cut, and the two wires from the sensor run directly to the coil to compensate.
But I don't know enough about the internal workings of the ignition module to know if that's even possible.
That pickup doesn't look stock, and it definitely doesn't have the right wires to be the OEM one. The way it is wired sounds aftermarket, too.
I saw this after I posted my previous thoughts. Thanks for commenting.
You are right, the sensor/pickup does NOT look stock according to the wiring diagram but whoever put it in there replaced the pop rivets on the outer cover. Based on the "unmolested" look of the timing enclosure I assumed it was an original setup.
I wonder if it was installed during the time that the S&S carb and performance exhaust was put on. But why would someone replace the sensor/pickup with a carb/exhaust modification?
So I'm kinda doing this thread now just to think things through.
Last night I traced continuity on a lot of the wiring harness from coil to switches to ignition module. All checks were good, no breaks in any wires.
I found where the PO had disconnected and tucked the harness connection for the OEM sensor/pickup behind the oil tank. I pulled it out, cleaned it good and did a repair on the green wire that had been scalped a little by rubbing against something. Then I did a continuity check on that section of the harness. It was good as well; all wires checked out.
Why the PO replaced the sensor/pickup with an incorrect part I can't figure out. but to make it work, he had to wire it directly to the coil, then bypass the ignition module/coil hookup. Strange thing to do, but it ran pretty well the way he had it wired.
My next step is to test the ignition module to make sure it is good. I'm thinking it might be bad and that's why he bypassed it with a different sensor/pickup. If it passes then I'll get a new sensor/pickup and wire it back according to the factory service manual wiring diagram and see what happens.
04-05-2016 | 09:29 PM
Timing Sensor Wired Directly to Coil????
