Persistent Electric Gremlin 2012 FLHX
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Joined: Dec 2021
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Persistent Electric Gremlin 2012 FLHX
Hey folks, after 6+ months of headaches and a trip to the HD dealer last week. I'm about to part out my 2-012 FLHX. I originally joined this forum with my first Harley back in 2008, but I can't remember my login, so I signed back up with my Gmail.
I'm hoping to get some fresh eyes on this intermittent no-start issue with my 2012 Harley Street Glide (FLHX, Twin Cam 103 engine) that has about 50,500 miles on it. The bike runs great once it starts, but sometimes (hot or cold) it just cranks without firing—takes multiple tries before it catches, very random; sometimes 1 try, sometimes 10+ cycling the ignition/key does nothing. I've confirmed via an inline spark tester that during these no-start episodes, there's no spark at either the front or rear plug. When the spark does show up, it starts right away. No consistent DTCs popping up, though I've checked multiple times.
Here's what I've done so far to troubleshoot and rule things out:
Thanks!
I'm hoping to get some fresh eyes on this intermittent no-start issue with my 2012 Harley Street Glide (FLHX, Twin Cam 103 engine) that has about 50,500 miles on it. The bike runs great once it starts, but sometimes (hot or cold) it just cranks without firing—takes multiple tries before it catches, very random; sometimes 1 try, sometimes 10+ cycling the ignition/key does nothing. I've confirmed via an inline spark tester that during these no-start episodes, there's no spark at either the front or rear plug. When the spark does show up, it starts right away. No consistent DTCs popping up, though I've checked multiple times.
Here's what I've done so far to troubleshoot and rule things out:
- Compression check: Dealer tested and got ~110 PSI (both cylinders similar). They noted some scoring on the cylinder walls and suspect bad rings, but they didn't answer my original question, why no spark... the bike fires instantly with spark present. Sure it may be a little sloppy on compression but I fine it hard to believe that is causing the no spark.
- Charging system: Replaced the regulator/rectifier with a new one as a precaution, but it didn't resolve the intermittent no-spark. Voltage is now stable (13.8-14.5V at idle, up to ~14.8V at higher RPMs).
- Crank Position Sensor (CKP): Tested resistance (within spec, ~0.9-1.1 ohms) and AC voltage output while cranking (~4V max fluctuating). Swapped with a new (non-OEM from Amazon) sensor and got the same readings. Since the problem persists and output is consistent, I'm ruling this out for now—seems marginal but functional based on manual specs.
- Other electrical basics: Battery is brand new, started here 6 months ago (holds 12.6V+ at rest, doesn't drop below ~10V during crank). Swapped all relays with brand new ones. Grounds and fuses checked/cleaned. Wiring harness inspected for chafing/corrosion (no obvious issues), and I've wiggled connections while cranking without inducing changes.
- Fuel system: Fuel pump cycles on with the run button, and dealer confirmed fuel PSI is okay.
- Not yet tested/replaced: Ignition coil (planning resistance and trigger signal tests next), bank angle sensor, or deeper ECM scan. I have a Power Commander V (PCV) installed as a piggyback on the OEM ECU, but the symptom persists even when I remove the PCV.
Thanks!
Last edited by phillipjplatt; Jan 25, 2026 at 03:27 PM.
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Joined: Aug 2006
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From: Pennsylvania
My thought on the coil was because the OP stated:
which to me means something that is affecting the spark or signal to generate the spark. Intermittent is always difficult to find.
Loose wires, shorting wires or connections not tight could be the issue. Because no codes, the electrical diagnosis manual would be the best bet if there is one. If the bike has a tuner on it that may be the issue - do not know though.
OP, let us know what you find out.
I've confirmed via an inline spark tester that during these no-start episodes, there's no spark at either the front or rear plug.
Loose wires, shorting wires or connections not tight could be the issue. Because no codes, the electrical diagnosis manual would be the best bet if there is one. If the bike has a tuner on it that may be the issue - do not know though.
OP, let us know what you find out.
Last edited by CoolBreeze3646; Jan 26, 2026 at 06:19 AM.
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From: OH
[QUOTE=CoolBreeze3646;2220601 If the bike has a tuner on it that may be the issue - do not know though.[/QUOTE]
It does / did , the OP removed it, no change
It does / did , the OP removed it, no change
Last edited by eighteight; Jan 26, 2026 at 07:27 AM.
Road Captain
Joined: Apr 2010
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From: Central Utah
Did your intermittent troubles start by chance (6 months ago) right after you replaced the battery? Try the RG battery and see what happens.
IIRC, Ive read the tach should read about 300rpm when cranking for the CKP to do its job of sending its pulse signal to fire the plugs.
Sluggish but sounding ok cranking vs a healthy crank might be your intermittent spark.
Or as CoolBreeze suggested the coil and its connections need checked.
IIRC, Ive read the tach should read about 300rpm when cranking for the CKP to do its job of sending its pulse signal to fire the plugs.
Sluggish but sounding ok cranking vs a healthy crank might be your intermittent spark.
Or as CoolBreeze suggested the coil and its connections need checked.
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,143
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From: San Diego, CA
- Crank Position Sensor (CKP): Tested resistance (within spec, ~0.9-1.1 ohms) and AC voltage output while cranking (~4V max fluctuating). Swapped with a new (non-OEM from Amazon) sensor and got the same readings. Since the problem persists and output is consistent, I'm ruling this out for now—seems marginal but functional based on manual specs.
I believe the minimum spec is 3V, but think 5V and up is normal.
If your original CKP was the issue, and you replace it with an Amazon clone, with the same readings, that doesn't in my mind justify the original readings. I am very weary of Amazon clone electrical parts...
I'd be tempted to get rid of the amazon clone CKP and get an OEM CKP to check it. Even if borrowing one from a running bike just to test...
Below is a video, where the guy shows how to test for spark...
He shows how to test the coil and the CKP.
At 5:35 he demonstrates how the CKP works and what you are testing, with a Harley bottom end on a bench, moving the flywheel by hand.
At 7:27 he shows how the CKP makes/sends voltage to the ECM. He gets the voltage to 7V just moving the flywheel by hand.
My point is that at "(~4V max fluctuating)" you are reporting, your CKP may not be making enough voltage to signal the ECM to fire the spark plugs...
I'd try an OEM CKP before parting out the bike...
That's all I got from what you are reporting...
Last edited by hattitude; Jan 26, 2026 at 10:39 AM.
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From: poway
The correct resistance for the crank sensor is about 1000 ohms.. Not 1 ohm..
Add: If you look closely, There is a small K at the top of the DMM display. The number 1.015 K ohms.
When the guy spins the crank, the max he gets is only about 0.7 Volts.
I would not trust this guys diagnostic abilities and after seeing his job on the tensioner change, not much else.
Add: If you look closely, There is a small K at the top of the DMM display. The number 1.015 K ohms.
When the guy spins the crank, the max he gets is only about 0.7 Volts.
I would not trust this guys diagnostic abilities and after seeing his job on the tensioner change, not much else.
Last edited by Max Headflow; Jan 26, 2026 at 12:27 PM.
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Seasoned HDF Member
Joined: Sep 2008
Posts: 14,143
Likes: 11,214
From: San Diego, CA
The correct resistance for the crank sensor is about 1000 ohms.. Not 1 ohm..
Add: If you look closely, There is a small K at the top of the DMM display. The number 1.015 K ohms.
When the guy spins the crank, the max he gets is only about 0.7 Volts.
I would not trust this guys diagnostic abilities and after seeing his job on the tensioner change, not much else.
Add: If you look closely, There is a small K at the top of the DMM display. The number 1.015 K ohms.
When the guy spins the crank, the max he gets is only about 0.7 Volts.
I would not trust this guys diagnostic abilities and after seeing his job on the tensioner change, not much else.
Wow... I totally misread the meter... my bad... I need to remember there's a reason I shy away form electrical advice..
Thanks for catching that...
Never saw the guy before. Now I'll have to look up his tensioner change... but I suspect I'll agree with you..
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From: poway