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Drawkward
| | Posted on Tuesday, October 21, 2008 - 02:39 am: | 
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While riding today to go pick up some parts for a friend's Sportster, the bike just quit on me. Not bogging, not stalling, just turning off.
I have already taken the carb apart and cleaned it thoroughly and replaced the "bad" ignition pick up which I thought was the culprit.
Now, it is happening again. I finally got the bike home and took off the points cover to find the new pickup in perfect condition (i.e. not melted).
Does anyone have any ideas at all???
4 hours later.....
So I've tested everything the book tells you to (Ign Module Test, Ign Coil Test, Ign Pickup heat temperature test with a blowdryer) and this is what I came up with....
During the Ignition Resistance Test - Ignition Module Harness where the conditions are:
Engine stop switch - Off
8Pin Ign Module Harness - Unplugged
3Pin Ign Sensor Harness - Unplugged
After completing those steps I proceeded to check the black connector that the Ign Module connects to (I am pretty sure this connector is what is supposed to be tested since in this config the Ign Module is completely unplugged and isolated). I found that the ground (pin7) was good (0 ohms - grounded properly). However, pins 1 and 4 (W/BK and PK) showed resistance. Pin1 is connected to the positive side of the coil, side 86 on the Ign relay and Engine stop switch. Pin4 is to the negative side of the coil.
This would mean that there is a short somewhere along the wire? Right??
When I turn the Engine stop switch to the ON position the resistance goes to 0, which would make sense, I think.
So, either there is a short somewhere along the harness, which is hard to believe, or the Ignition stop switch is bad....right?
I disconnected the pos and neg wires to the coil and did the test again and the only side that is showing resistance is the positive side, which also connects to the Ign Relay and the Engine stop switch.......
That has to indicate that there is either a short/ground or the switch is bad. I tested the relay as it is outlined in the manual and it checked out OK.
Am I missing something??? |
Bombardier
| | Posted on Tuesday, October 21, 2008 - 04:12 am: |
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Had a dirt bike that used to do the same thing to me.
10 kilometres up the beach amongst the sand dunes on a sweltering summer day and ................push city.
Turned out to be the coil. As the coil heated up it shorted/grounded and that was that.
May well be your problem. |
Sparky
| | Posted on Tuesday, October 21, 2008 - 03:16 pm: |
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As long as you are checking for continuity (with the battery disconnected I hope), pin 1 at the ign module connector (W/BK wire) goes to one side of the coil and to the right handlebar switches for engine on/off and start. However, you should not have continuity to pin 86 of the ign relay (as compared to a '98 S3 wiring diagram). Pin 86 is the +12 VDC from the ign fuse.
If anything, you should have continuity from pin 1 of the ign module connector to pin 87 of the ign relay if the engine on/off sw is in the Run position and no continuity to pin 87 with the on/off sw in the Off position.
Try disconnecting the wires at the rt handlebar switch connector and repeat the continuity test. You should only read coil resistance (2.5 to 3.1 ohms) at pins 1 & 4.
Did you try the voltage tests for the ignition circuit as called out in the service manual? It checks the neutral, sidestand and clutch switches as well as the ignition relay and all the wire harness wiring in between. All this must be 100% serviceable and reliable for trouble free operation.
Have you bypassed the sidestand switch? If not, check it for continuity, as those are known to go bad over time. The ignition coil depends on that for its ground connection during normal "Run" operation. |
Drawkward
| | Posted on Tuesday, October 21, 2008 - 09:51 pm: |
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Sparky:
I was wrong, had my numbers mixed up.
I put on the new coil today and the bike started up but cut out at around 1.5 minutes...and would not start after that.
Called my uncle up (master harley mechanic) and he told me to get my ass to the store and buy a test light(I already had one, haha).
He told me to probe the signal wire that's on the coil to see if it was turning on and off, signaling that the module was sending the signal to the coil to fire. It wasn't, as far as I can tell. Which means, I think, that the module is bad.
I tested the Ign pickup to see if the impedance was changing (due to the hall effect) as the motor was cranking and it was...so the pickup is good.
The only thing left in the circuit is the module.
Anything you guys think I'm missing in that deduction??? |
Sparky
| | Posted on Tuesday, October 21, 2008 - 11:59 pm: |
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Because your bike runs for a while then doesn't, that unfortunately means you have an intermittent failure which also means you have to test things when the bike doesn't work. Don't go replacing parts until you can verify something is broke.
You said, "I've tested everything the book tells you to...". Did you do the ignition voltage tests called out in the factory service manual?
If not, there could be a bad neutral switch or clutch switch or sidestand switch that is interrupting the voltage to the ignition relay, causing you to think that the ignition module is bad.
Try swapping the ignition relay with the starter relay and see if that changes things. Check out that sidestand switch; make sure it does not open-circuit when the sidestand is up. |
Drawkward
| | Posted on Wednesday, October 22, 2008 - 01:48 am: |
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I got on the bike, turned the ignition on with the clutch in and the sidestand up...I tested for a ground on the tan/white wire like it says in the book and lo and behold it was grounded. Indicative of a faulty switch?
I bypassed the switch but the bike still doesn't run...
Also, I think I tried the Ignition Voltage test. The manual just may have it worded wrong...what's the gist of the test?
Thanks for the patience.
(Message edited by drawkward on October 22, 2008) |
Sparky
| | Posted on Thursday, October 23, 2008 - 03:24 pm: |
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OK, you've got a good ground on the tan/wht wire. That's half of the problem solved. Where did you test the TN/W wire, at the sidestand switch or the ignition relay?
What I want you to focus on, IMHO, is whether you are getting ignition voltage (+12 VDC) at the ignition relay on the gray wire on relay terminal 87 with the key on and the engine On/Off switch to On. That wire sends ignition voltage to the On/Off switch and the W/BK wire to the ignition module and the coil.
If it's getting voltage there (terminal 87) under normal run conditions, but not when the bike stops running (your original problem), then the other half of the mystery is identified and further troubleshooting can go down that path.
The fact that it hasn't blown a fuse yet kinda makes me think you're either losing a ground somewhere or there's an intermittent broken wire in the ignition circuit. |
Drawkward
| | Posted on Friday, October 24, 2008 - 11:02 am: |
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Module was replaced and that solved the issue.
I was having trouble verbalizing everything I tested, Sparky, but I checked the things you told me to and it all was good. The only other thing I could think of was the Module. I wasn't getting a spark across the pick up terminals in the plug from the module and the book says that is indicative of a faulty module.
I just replaced it with the same model.
If I would have known it was the module from the beginning I think I would have just bought a brand new SINGLE-FIRE ignition instead.
I guess you live and you learn.
Thanks for the help, and hopefully this thread will serve someone else in the future.
Be Diagnostic. Not a Mechanic (i.e. don't just replace shit!!!)
Thanks again!!! |
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