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Reoplacing the ignition module on a 1998-2003 Sportster
The original module worked good on idle (not so go on hight revs) but when the bike got hot it stoped giving spark until the bike cooled down and then it was like before so I went ahead and ordered a simple Dyna S module copy kit with coil with no advance features like for VOES or rev limits https://www.ebay.com/itm/185542693341 . This should be a simple installation with having just 2 wires that go to each side of the coil and then you supply another wire with 12V conection to the same side that doesn't have continuity to the back plate of the module I reused the same connector that supllied 12v to the oem coil from the main wiring harness). So here is my problem: when I hook up a test light to the coil and the light should be off until you move the module to the correct position BUT in my case the light stays on allways!
What could I be doing wrong? In the begining I thought the module that I bought was bad but I got a secong one rom another seller and it's the same problem... I don't think the problems are with the replacement modules but with something how I'm connecting everything.but I don't figure out what could be the problem.
Any thoughts?
PS:
Since those years of Sportsters where the only ones that had the hole electronic ignition module inside the point cover I don't know if there is something that I'm not taking in to account that might be the reason why the test light is staying on always... maybe I also have to eliminate something compared to a previews year model?
Last edited by El Chiguete; Jul 23, 2025 at 12:59 PM.
Can you show us a wiring diagram for your bike, and also for the Dyna S module? A couple pictures would be easier than trying to decipher your text, it's a bit confusing.
The ad you posted says to contact the vendor with any questions, have you tried that? It's only two wires, does that module also advance the timing, or is it just a replacement sensor?
John
Last edited by John Harper; Jul 23, 2025 at 01:29 PM.
I see no mention of a mechanical timing advance. The Dyna S is not like the original unit in that it does not use the timing cup/voes like stock. It uses weights/springs/magnets to advance the timing so if you are using the cup still it will not work.
Last edited by OCSpringer; Jul 23, 2025 at 01:48 PM.
This is the original ignition module with 5 cables that connecto to the main wiring harness.
Since this is obsolete and they don't make new ones anymore I got a copy of the Dynatek S module on eBay. As you can see on the wiring diagram it's a simple connection of two wires (one to each side of the coil) and a third wire that provides the 12v. BTW i bought installed a mechanical unit for the module to sense.
The way that im tryin to set up the timing is to use a tester light connected from the blue wire that goes to one side of the coil to ground and then rotate the ignition module until it lights up... BUT my problem is that the tester light stays always on insted of stay off until I turn the module to the correct position.
So what could be causing this and do I have to take in to accout anything when replacing the original ignition on this generation of Sportsters?
Hmm. I have static timed the Dyna S quite a few times in the past with no issues. I always just hooked it up, making sure the motor was at TDC on the compression stroke (lined up the timing mark in the timing hole at the base of the cylinders) and advancing/retarding the ignition module until the light turned on.
Here you guys can see what I'm talking about the tester light that is supposed to turn on when the timing is correct (skip ahead to 8:06) vs staying on allways like it's happening to me now.
Are there any wires connected to the coil terminal besides the blue wire? I also see a wire from the original ignition module to the bank angle sensor, perhaps that's causing an issue. I found a wiring diagram and was trying to trace the 5 wires from the original module. I also see a Violet/White wire but can't see where it goes. I think I'd look at what was deleted from going from 5 wires to 2.
How is spark advance handled with that Dyna S module?
John
Last edited by John Harper; Jul 23, 2025 at 06:30 PM.
It replaces the timing cup and as the cam gear spins the lobes expand out as the centripetal force overpowers the spring tension advancing the timing as the rpms increase. You can change when it advances by putting stiffer springs on. There are three spring types denoted by different colors (black, gold, silver).
Last edited by OCSpringer; Jul 23, 2025 at 07:24 PM.
I have a Dyna S on my 77 and have installed on quite a few other Harleys, so I a good idea what's going on here. Reading you text I see "I got a copy of the Dynatek S module on eBay." So congratulations ya got what ya paid for, a cheap knockoff from China that does not work.
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Reoplacing the ignition module on a 1998-2003 Sportster
