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Chasing an intersting bug

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Old Oct 23, 2021 | 04:16 PM
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From: denver
Default Chasing an intersting bug

Get this,

My 04 Electraglide classic EFI was running fine, just getting an irregularity on the volt guage. It was jumping up and down intermittently. Got it home and shut it down, never started again.

I changed the battery because it was toast. Pulled error codes for voltage regulator, coil, and Crank Pos Sensor. Tested all, changed all. Cleared codes, bike still won't start with the Crank Pos Sensor code returning,(p0374) Tested part. All good. Tested wiring, continuity all the way to pin 30, and 12 of ECU(red and black wire). Wiring is good.

Talked to a Harley tech, he said it's either the ECU or flywheel damage. Is it really a bad battery that roasted my system? Could my ECU be effed? Don't know how the flywheel could've been damaged.

Someone please advise.
 
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Old Oct 23, 2021 | 04:36 PM
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Unplug CKP and make sure neither lead is common to ground. Only other test is to check AC volt from CKP while cranking, minimum 1Vac.
 
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Old Oct 23, 2021 | 04:38 PM
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Originally Posted by sullyegc
Get this,

My 04 Electraglide classic EFI was running fine, just getting an irregularity on the volt guage. It was jumping up and down intermittently. Got it home and shut it down, never started again.

I changed the battery because it was toast. Pulled error codes for voltage regulator, coil, and Crank Pos Sensor. Tested all, changed all. Cleared codes, bike still won't start with the Crank Pos Sensor code returning,(p0374) Tested part. All good. Tested wiring, continuity all the way to pin 30, and 12 of ECU(red and black wire). Wiring is good.

Talked to a Harley tech, he said it's either the ECU or flywheel damage. Is it really a bad battery that roasted my system? Could my ECU be effed? Don't know how the flywheel could've been damaged.

Someone please advise.
What does never started mean to you? Does the starter turn when you hit start button?
Did you have the "new" battery tested?
Do you have 12+ power at starter lug?
Do you have power at starter trigger wire?
 
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Old Oct 23, 2021 | 06:10 PM
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From: denver
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Originally Posted by im
What does never started mean to you? Does the starter turn when you hit start button?
Did you have the "new" battery tested?
Do you have 12+ power at starter lug?
Do you have power at starter trigger wire?
Rolls over, not even a sputter. It is definitely spark related. New battery is good. All power to starter is good.
 
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Old Oct 23, 2021 | 07:39 PM
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Originally Posted by Vernal
Unplug CKP and make sure neither lead is common to ground. Only other test is to check AC volt from CKP while cranking, minimum 1Vac.
I checked the new CPK. It is giving me the recommended voltage. I traced the wires back, and I have continuity to the ECM.

Are you saying that a grounded short on either lead would give me appropriate continuity in the designated ECM pin?
Please advise. Thank you!
 
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Old Oct 23, 2021 | 08:33 PM
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No, the manual wants you to make sure the the two wires to the CKP are not shorted to ground.

The ECM controls the ground for the system relay. The kill switch provides power to the start button and to the coil on the system relay, the ECM provides ground for that relay for 2 seconds once the kill switch is turned on, you hear the fuel pump run and shut off. The ECM will ground the coil to the relay again once it receives the voltage from the CKP telling the ECM the engine is rotating. The System relay not only powers the fuel pump but the ignition coil and fuel injectors too.

Do you have schematics?

If the pump does run with ign and kill switch on we know the circuit is good.

Hook up your meter and check continuity from the GN/O wire, pin 4 on the ECM to ground. You should see continuity to grd for the 2 seconds when you turn the switches on and again when the starter kicks in.

You could try grounding the GN/O wire and see if the bike will run but be aware the fuel pump is running when ever the kill switch is in run.

Did you take a good look at the pins and connector to the ecm? Clean and straight all wires look even, none pulled out a bit?


 
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Old Oct 24, 2021 | 08:54 AM
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From: denver
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Thank you for the explanation.

I do have the schematic, and I also have a question that might be dumb. How do I check continuity of pin 4 while the ECM is plugged in?
 
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Old Oct 24, 2021 | 10:50 AM
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Not a dumb question at all, the connector for the ECM is sealed so you can't get to the wire ends. A better method may be to just look for 12V on the fuel pump fuse, when the system relay is energized the fuse will have 12V.

Does the fuel pump come on when you turn ign and kill switch on?
 
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Old Oct 29, 2021 | 02:02 PM
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From: denver
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Yes, fuel pump runs.
 
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Old Oct 29, 2021 | 04:36 PM
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If the fuel pump runs when you first turn on the Ign and Kill switch the relay is fine. If you put your volt meter on the fuel pump fuse and ground and crank the engine and do not see 12V then the ECM does not recognize the input from the CKP or if it does for some reason the ground does not close for the system relay.

I would pull the system relay, and either jump the ECM power to the fuel pump at relay or just jumper 12V to the fuel pump fuse and quickly start the bike. With 12 v on the pump the fuel pump is running 24/7. If it runs I would suspect the ECM.



 
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