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Bad coil??? I hope!!!

29K views 32 replies 10 participants last post by  kd5cqt 
#1 ·
Had a problem last week getting fire in both cylinders. I changed the plugs, and everything ran good. THIS week, I started it a couple of times, and it ran great. I went home today, and tried to fire it up, and nothing. I mean NOTHING. Can anybody tell me how to test for a bad coil? I can't really afford any expensive fixes right now, so I'd like to try and isolate the problem, and try to fix myself. Problem is that I don't have very much equipment. An ohm meter, and new plug wires, and relatively new plugs.

Any suggestions?
 
#4 ·
Have you checked for codes, and more specifically a bad crank sensor?
 
#6 ·
#7 ·
O.k. Dave....learned a little about the computer on my bike. When I ran the check, this is what came back....These are the codes it showed in order. d01CLr,d02CLr,d03CLr,d04CLr,d05CLr,d06CLr,d07CLr,d08set,d09CLr,d10CLr,PPU,82883......found this on another thread, and my codes are identical.

I also found some information about testing the coil. When I tested the primary windings, the readings were off a little. I wasn't real sure which of the 2 leads to test. There were three where the wiring harness hooks up. Depending on which set of leads I checked, the readings came back from .9 to 1.4 ohms. The advice I found said it should be between 2.5, and 3. The secondary windings tested in normal range. At this point, I'm thinking the coil, but I hate to keep throwing money at the bike without fixing the problems. I'm allready into a new set of plugs and wires. Minimal I know, but I have champagne dreams on a budweiser budget.

Any ideas?
 
#8 ·
Check to see if you have voltage at the coil connector . Unplug the connector from the coil and use a test light . With ignition on the B contact should light the test light . Now hook the test light clip to the pos. battery terminal and probe the A and C contacts while cranking the engine , they should flash while cranking . The coil values you got when testing it sound like they're within spec . If the tests at the coil connector are good then there's either an open wire or the CKP ( crank sensor ) is bad .
 
#11 ·
o.k....hold the phone. 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. .5-.7 primary. I can't remember the secondary off hand, but they were within spec. 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.

so, SCHMIDTYS, I decided to try what you advised 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, 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....
 
#15 ·
When you tested the A and C pins did you have the test light clip hooked to the positive post of the battery ... not ground ?
You can test the CKP . Disconnect the CKP connector and check resistance at the pins , should be approx. 1000 ohms . The connector should be under / behind the regulator on your bike .
NOTE : Don't touch anything else with your test light while its hooked to the battery positive post .
 
#12 ·
I just wanted to follow up on our talk about ckp sensors. I got home from work, and pulled the ckp sensor off again to take a closer look at it. Someone else told me that if I saw metal, that it was worn out, and probably bad. Well, there is a small round magnet at the center (silver) but it really doesn't look like anything is worn off. It just looks like it is supposed to be like that. I saw a picture that was posted and on that one, it looks as if it has a plastic coating. Can anyone tell me anything they know about worn out / bad ckp sensors?.....please?
 
#14 ·
How did you check/find out that you have no spark? did you pull one plug out of the cylinder with the wire attached and ground it while cranking the engine over? Is the engine getting fuel? more info on the problem needed/what have you done so far to troubleshoot?
 
#16 ·
I tried that with the spark plug. I am getting spark, and fuel. I can get it to fire every now and then, but it is if it's out of time or something. When I pull the plugs out, they are wet with fuel. I have tested the coil, and it seems to ring out good.

When I tried the connection to the coil, I grounded the light to test the b lead, and I got a light. I attached it to the pos. terminal when I checked the a and c ports.

O.k., I would really like to test the ckp, but I'm not even sure where the regulator is on my bike. I am just getting familiar with this bike. I hate to sound so nieve, but please help, I'm desperate. When I was looking at the sensor, I was just looking at where the wires go, and I get lost after the first wire loom. I can't really follow them, much less see where they terminate.
 
#17 ·
The regulator is at the bottom front frame ahead of the oil filter , the wire from the stator goes to it . Unbolt the regulator ( 2 bolts ) and let it hang , the stator plug and CKP plug are behind the regulator bracket . Unplug the CKP connector and test ohms at the CKP pins , should be about 1000 ohms . If the CKP resistance is out of range the engine timing will be off enough that the engine wont start .
 
#19 ·
I was able to find the connector for my ckp sensor, and tried it out. Mine read 1050, or 1100 ohms. So I think I can rule out the sensor. My shop manual arrived today, but it appears as though I needed the electrical diagnostic manual. Figures. I was going to test some of the other stuff, voltage regulator, and what else I could find to test. I'll have to wait unless anyone can volunteer some information.

It is appreciated!!!

p.s., what should the test reveal of checking the coil connector. Like I said, I can get the test light to light up on the center terminal only. Nothing on A, and C though, and yes, it's hooked to the positie battery, ignition on, and cranking.
 
#20 ·
The test at the B contact is for battery voltage , it charges the coil . The test at the A and C contacts are testing the trigger circuit of the ignition . Each time they light the test light the coil should discharge to the respective plug .
I'm hoping you did the other obvious checks like the fuses , checked with a test light not the eyeball !
Another thing , 1100 ohms at the CKP is a bit high . Make an accurate reading of the ohms . The reason I say this is that the ECM program is looking for a range within a parameter , the CKP may not be shot but just out of the parameter . The CKP is an inductive pickup with a coil of wire and a magnetic core that can wear out from vibration and go out of range of the specified parameter .
 
#21 ·
Another thing about where the CKP connector is located , I was going by where they are located based on an '02 Heritage Softail I worked on 2 weeks ago . It was behind the regulator plate . Your MoCo service manual has a section at the back that shows connector locations .
 
#25 ·
That would be within parameters . I've got a brand new CKP at my shop and it measured 1015 ohms yesterday . I still wouldn't rule your CKP out as the problem .
Other things that could cause the A and C terminals to not get their signal are a faulty TSM or a poorly crimped wire pin contact at the TSM connector or a faulty ECM .
The BAS ( bank angle sensor ) located and incorporated into the TSM can cause the engine to not start . Also I have run into the bad wire crimp thing at the TSM connector before , a real bitch to diagnose I might add .
To get into diagnosing electrical problems in depth requires the Electrical Diagnostic Manual .
Now , if you had a buddy with a bike that would loan you his / her CKP just to try in yours would be nice . CKPs are all the same except for wire length and where the wire angles out of the CKP .
 
#26 ·
So, I'm just not sure where to go from here. I've checked my coil, and it's within spec, and my ckp sensor as well. I am hoping to be able to check more once the diagnostic manual gets here. I hate the thought that my sensor, and my coil test out o.k., but either, or both could still be bad. I hate this small town I live in. The only motorcycle dealer is in the next town, and THEY don't have a way to test the coil dynamically. Thanks for suggesting some other things. I'll have to get ahold of that manual, and dig in from there.

I hate to sound redundant, but here it goes....before it quit running...it would run pretty good, but miss here and there. Then it would run on one cylinder. Ran like that for a little while, not on the road, but when I started it up. Even took the front plug wire off, and put it on the back cylinder...that would make the back fire. At that point I decided it was the plug wires. After changing the plug wires, ran good for a trip around the block. Next day, firing on one cylinder again. Later that day, started one more time, and then just quit. Wouldn't run anymore after that. I hate to keep stating the obvious, but whatever it is, kind of went gradually downhill, and then just quit alltogether. Can any of these symptoms be used to isolate the problem?
 
#27 ·
I just reread all your posts and noticed that you didn't mention cranking the engine over while testing the A and C contacts , you won't see the test light flash unless you're cranking the engine at the same time .
From the measurements you took at the coil the numbers you came up with sound good , I'd rule the coil out untill you get the A and C coil connector contacts to register voltage . The coil won't fire the plugs untill it receives the trigger signal . The Electrical Diagnostic Manual has an elaborate diagnostic flow chart outlining the test procedure pinpointing the coil connector , about 3 pages long . At certain points the flow chart directs you to install " breakout boxes " which you won't have access to , bypass those tests and continue through the flow chart with your multimeter and test light .
Try finding a CKP that you can plug into your bike to either confirm or eliminate your CKP as the problem .
 
#28 ·
Understood, and yes, I was cranking the motor when testing the A, and C contacts. One thing I don't understand is that the light doesn't light up, but if I pull the plug wires and hold it just off the plug, it fires. So why would voltage get to the plugs when that happens, and not when the plug wires are installed, or the test light is at those contacts?
 
#29 ·
You get spark because you changed the circuit resistance , the spark had to jump the air gap . If you would have had the test light in series with the A or C pin at the same time you would have seen it flash .
I've had similar experiences with earlier Sportsters and Dynas , wouldn't start do to no spark , put the spark tester in series with the plug and plug wire and the engine fires . The spark tester caused the circuit resistance to rise . In the case of the Sportsters and Dynas replacing the ignition pickup remedied the symptom .
In a nut shell , you can get spark and you say it's getting fuel but it's not starting . If I had to take a guess and just throw one part at it ... CKP . It's firing the plugs and it's getting fuel but the timing is off .
Did ya get your electrical diagnostics manual yet ?
 
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