Bad coil??? I hope!

[Guy Rand]

o.k., don't have all the readings, but here is what I got.

power to front=.9
power to rear=.9
front to rear=1.5 or so.

on the secondary, I didn't realize how to check all the readings, just front to back, and I don't remember exactly, but it was 13,800 to 14,800, something like that. I am away from the bike right this second, but that's the best I remember.

Is that any help?

 

[Hoople]

The dual primary is created by a center tap. It would be very unusual to have 2 shorts of the same magnitude, one of which was on each winding. Possible but unlikely. Having exactly .9 & .9 indicates no short but at the same time anything under an ohm is getting really low. Coils that have such a low primary resistance like that are usually found only (not always but usually) with capacitor discharge ignitions. I don't think that is what you have. By chance would you have access to a scope with a 10X probe OR an 8 ohm ballast resistor and a condensor out of an old chevy or VW. I can tell you how to trigger the coil without the bike electronics.

 

[Jonas]

o.k., don't have all the readings, but here is what I got.

power to front=.9
power to rear=.9
front to rear=1.5 or so.

on the secondary, I didn't realize how to check all the readings, just front to back, and I don't remember exactly, but it was 13,800 to 14,800, something like that. I am away from the bike right this second, but that's the best I remember.

Is that any help?

Sounds right to me. .9 ohmns - .3 meter error = .6ohms

Secondary. I am not 100% how to check this, but when you go from plug wire to plug wire connector. I think you are measuring across both secondary coils. If true you should have 11K to 15K your 13.8 to 14.8 fall right in range.
I believe the small power terminal to each plugwire connector will give you the individual secondary coils.(I'm just not sure)

If you get a chance can you check again, the numbers from my previous post. Mostly on the secondary side.

Thanks

 

[Guy Rand]

o.k. Jonas, I took my coil to work, and checked it with another volt meter. I got some different readings, and realized some information/questions about which lead to use to test what prong on my coil. I don't know which lead to use for the power, and which lead to use for the front or rear coil. I decided to use the positive lead for the power, and the negative lead for the front/rear. When I did on the primary side, I got 2.2 - 2.6 ohms....sometimes I would get different readings...from 1.8 to 2.4. At first I thought maybe my leads were coming off the prongs, but I really don't think so, it just seems like I'm getting different readings. At least with this volt meter. I am going to check it again when I get home. The rear to front coil was 2.2 to 2.5.

On the secondary side front terminal was 6,000, and rear was about the same. Front to rear was about 12,000. Does any of this indicate if the coil is bad? What else to check?

 

[Jonas]

Polarity of the leads should not matter checking continuity of a coil. It will be interesting to see what you find out at home.

The 12k ohms for the secondary sounds good. So when you got the 6000ohms on each secondary was one lead on the Power small terminal?

Primary readings measurements seem high. And do not really make sense.

Front to Rear should = (Power to Front) + (Power to Rear).



Not coil related, but I would check the connection of the ECM plug, maybe connect and disconnect.

From your earllier post about the plug wires, seems this problem is intermittent.

Do you know if you have a Power Commader on the bike? If you look at the plug going to the ECM and all the wires are black(in color), more then likely you do. Take the Power Commander out and try it.

 

[Guy Rand]

o.k., back to where I was last night. Primary, either side was .9 ohms, front to rear was 1.5.

On the secondary, (with one lead held to the power) front is 6.0 one side, and 5.9 the other. Front to back is 11.9. That's my numbers, and I'm sticking to it. I'm not sure about the equipment I was using at work, I'll stick with mine at home....that's the latest readings.

I was reading some of these posts at work today, and it seems like my coil might be o.k. I got two different sets of specs for where the ohms should be on the primary and secondary windings. They fell within range of the specs I got from one guy. Since I don't have a manual yet, I'm at the mercy of what other people tell me, and I just don't know for sure if any of these people have a 2001 Fatboy.

Someone else suggested that I try checking power at the harness that connects to the coil with the test light. When I tested the connection that goes to the coil, the b contact lit up. However, when I turned the ignition on and tested both the a, and the c contact while cranking it over, I got nothing....no light. So I need a little help here. If voltage isn't getting there, where do I check next? I checked for codes last night, but everything came back clear. I'm all ears....

 

[BUBBIE]

i gave you the numbers from my 2000 book and coils are the same.. your specks show okay.
primary 0.5-0.7 ohms
secondary 5.5-7.5K ohms bubbie

also on ckp sensor look at the end and see if it has a shinny metal showing ..mine did when it was bad.

 

[Jonas]

o.k., back to where I was last night. Primary, either side was .9 ohms, front to rear was 1.5.

On the secondary, (with one lead held to the power) front is 6.0 one side, and 5.9 the other. Front to back is 11.9. That's my numbers, and I'm sticking to it. I'm not sure about the equipment I was using at work, I'll stick with mine at home....that's the latest readings.

I was reading some of these posts at work today, and it seems like my coil might be o.k. I got two different sets of specs for where the ohms should be on the primary and secondary windings. They fell within range of the specs I got from one guy. Since I don't have a manual yet, I'm at the mercy of what other people tell me, and I just don't know for sure if any of these people have a 2001 Fatboy.

Someone else suggested that I try checking power at the harness that connects to the coil with the test light. When I tested the connection that goes to the coil, the b contact lit up. However, when I turned the ignition on and tested both the a, and the c contact while cranking it over, I got nothing....no light. So I need a little help here. If voltage isn't getting there, where do I check next? I checked for codes last night, but everything came back clear. I'm all ears....

I think you coil rings out good.

BUBBIES manual matched mine for your bike. Those reading sound fine, even better with the .3ohm static reading on your meter. So the .9ohm is more then likely a reading a little higher then it is. Thanks for the info on testing the secondary.

I do not know about that test light theory. The front and rear terminals go directly into the ECM.

Checkout my last post about the power commander.

 

[dboone]

I had the same thing happen to me on my 01 dyna and it turned out to be the ignition module. But I had an aftermarket Dyna 2000 module on a highly modified motor, I replaced it with a SE 7000 and haven't had any problems since...and I dont have to take the seat off and adjust the module for low octane gas like I did for the Dyna module. The SE module does the trick!

 

[Hoople]

I was reading some of these posts at work today, and it seems like my coil might be o.k. I got two different sets of specs for where the ohms should be on the primary and secondary windings. They fell within range of the specs I got from one guy. I'm all ears....

Guy, I am not trying to discourage your plan but I must inject because you may be going down a dead end street. I want you to realize that reading the correct ohmetric value of the primary and secondary windings of a coil does not mean the coil is Good. The ohms readings are only intended to separate "Toast from POSSIBLY Good". Remember that these coils are epoxy filled. If the die-electric strength of the secondary insulation has been exceeded, the epoxy will get punctured. Once that takes place, it is easier for the coil to jump the internal puncture than to jump the spark gap of the plug. Something as simply as bad spark plug wires can result in the coil getting punctured. Pulling a spark plug wire and telling the coil to put out it's maximum available voltage is 1 sure way of pushing your luck also.

Once punctured what you will have now is a coil that will pass the ohms test with flying colors but it won't produce enough voltage to jump the spark plug gap. That is the reason I had suggested earlier to dynamically test the coil with a ballast resistor & condensor. That will test the most important specification of a coil which is it's breakdown voltage or di-electric strength.

I admire your enthusiasm and would never try to discourage you. Just as long as you know that even if it ohms out perfect, it still can be bad.