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Xb12r_guy
Posted on Sunday, April 14, 2019 - 01:45 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Greetings fellow Buellers. I own a tuber (2001 Buell X1 Lightning) that I have been riding in shakedown mode after a year long restoration from a box of parts. I need some guidance on troubleshooting what appears to be an ignition problem but may turn out to be electrical.

Last night I was going about 80 downhill (straight unfortunately) and halfway down the hill I lost power to my gauges (speedo and tach). I slipped the tranny into neutral so I could coast to a parking lot at the bottom of the hill to troubleshoot the problem. While coasting I tried to restart the bike. It would turn over normally but it would not fire up. All this time my speedo and tach are lights out with no speed or RPM readings - trip meter out too. The LED shift/oil pressure idiot light bar remained on all this time as if nothing happened. Headlight and turn signals were working normal too!

Finally I parked the bike and removed the fuel tank without disconnecting the electrical harness or the fuel line and started digging around. I moved the different connectors around while I had the run switch in the run position and the speedo and tach blinked at me a couple of times but eventually they stopped. I could not get it to repeat the behavior. I checked the following in case anyone can narrow it down for me:

All fuses are 100%, diode fuses are good also (did diode test) All relays are good also (replaced them with new spares (2) that I carry). Main circuit breaker is good - changed with known good one I carry. I checked continuity of the grounds going to the instrument cluster and no problem there. Checked voltages at the connectors coming from the battery, 12V all the way.

Now hereís the crazy part that I have been saving for last! I hook up my negative meter lead to a known good ground bolt on the cylinder head and when I check the continuity to the grounds in the connectors, they read good. Then I switch the meter to voltage and I get 12V! Whoa! Never seen that. I am experienced in electrical troubleshooting but never experienced that phenomenon! So any ideas on where to start? Tomorrow night I will be checking for spark at the plugs to isolate that.

Thanks for any help!

Ed
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Akbuell
Posted on Sunday, April 14, 2019 - 01:27 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Um, first, with the electrical diagram at hand, trace backwards to see if the instruments have a common power source, or connector. Confirm that circuit good. Then check for a common ground to those instruments, and confirm it to be good.

Al at American Sport Bike had a mantra about Buells - Check your grounds ! Since the ign is also apparently involved, the first two places I would check are the battery ground cable (And pull/tug/ohm it) and confirm a clean, tight connection at both ends. Then do the same with the ground strap between the swing arm block and the bottom of the battery tray.

There was a recent post in the knowledge vault with a really good treatise on grounding. Or earthing, for the folks from Great Britain.

Hope this helps, Dave
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Xb12r_guy
Posted on Sunday, April 14, 2019 - 08:34 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks Dave! I checked the grounds today and the main ones check out ok (swing arm and under battery tray. No spark at the plugs but I do have 12VDC at the Grey cable going into the distributor. Will follow your suggestion to trace the fault from the gauges back to the source. Thanks again. Will keep you posted on progress.

(Message edited by xb12r_guy on April 15, 2019)
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Akbuell
Posted on Monday, April 15, 2019 - 11:17 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

You are very welcome.
As an aside, if you haven't already done so, might do to bypass the sidestand switch. A bad one can cause all kinds of problems, especially if the switch is in what I call a 'prefail' mode. I would do this first; the worst that can happen is a possible problem has been removed from the system. And the switch is one of the ground paths for the ign system.
Hope this helps, Dave
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Akbuell
Posted on Monday, April 15, 2019 - 12:26 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Looking at the wiring diagram, some things come to mind.

The speedo, tach, and speed sensor all ground 'into' a single splice (S20). 2 wires run 'out' of that splice - 1 going to pin 2 of the data link connector, the other to a splice (S17) that also connects pin 2 and pin 11 of the black connector of the ECM. The wire 'out' of that splice goes to what the diagram calls 'IGN ground'.

So if all of those wires are in good contact with each other, and pass the wiggle test, it would seem a check of IGN grounds is in order.

With the bike in neutral, clutch out, and sidestand down, the system grounds through the neutral switch. With the bike in gear, and the clutch in, the clutch switch grounds the ignition. With the bike in gear, and clutch out, ignition is grounded through the sidestand switch.

Pls let us know how it goes. Hope this helps, Dave
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Xb12r_guy
Posted on Monday, April 22, 2019 - 01:25 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hey Dave!

I came across the culprit before I got to your subsequent thread about the S20 ground connection. Yes it was there where the problem was! Thank you for your insight. You are correct, per Al of American Sport Bike! The grounds are the main culprit at times as it was in this case. I don't know where in the manual I can make reference to S20 connection point but one of the grounds on a ground connection point on the frame (under left side if tank towards rear of tank under bracket) was broken/severed. I suspect it was ready to fail because part of the break point looked corroded/worn.

I would like to figure out how to read where the different S connectors are located, especially the ground ones for future reference.

Anyway, thanks again for your help in troubleshooting this problem. I can ride my girl once again all week to work and have the time of my life!

Best regards,

Ed
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Jolly
Posted on Monday, April 22, 2019 - 10:38 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

When troubleshooting a recent issue on my S1W (turned out to be a previous owner issue of connecting wires to peanut bulb in the headlight) I started with grounds as well and found that same grounding point bad.. though it didnít fix the issue.

My first job in the military when I was enlisted had an extensive electronics course (13 months)... the rule of thumb was 75% of electrical issues was grounding faults.
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Akbuell
Posted on Tuesday, April 23, 2019 - 09:48 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hooray ! ! ! Glad you found the issue and the bike is now happy !

And Thank You for the update post. It adds to the community knowledge.

As to the splices, I suspect they are soldered joints, buried in the harness. Hence the suggestion of connecting the multimeter at the plug-in connectors at either end and doing the wiggle test. Probably the only way to actually see them would be to unwrap the harness and following a wire/s by hand to the splice.
Dave
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