Testing for Spark on M8 touring
#72
01-14-2024, 08:26 PM
Road Captain
You supposed to get system voltage (12.5V) on the red wire, unless the battery is low.These are basic checks you must do before looking elsewhere, so this is good experience for you. Also if you unplugged the CKP and got a code then a bad CKP should throw a code BUT not always. If you are getting ac volts it should be ok. See if the injectors are firing, ( a wet plug or put the leads ,red at red and black on the other terminal of the injector plugged in, and you will see 12V pulse) If its working CKP good if not CKP definitely bad. You will fix it soon.
#73
01-14-2024, 08:27 PM
Road Captain
My money is on the crank position sensor. There is no reliable way to say for certain it is good except to replace it.
This is what I've always believed...
There is no battery voltage to the CKP.
The pulse is not a pulse but a constant a/c voltage produced by the ckp sensor itself
The drop in a/c voltage caused by the missing tooth tells the ecm what stroke the engine is on.
The only way to test the ckp, is to UNPLUG it from the ecm, put a multimeter on the 2 wires, (R/B and B) and crank the engine. it should show 1-5 VA/C.
This is NOT 100% reliable tho as some will show good when they are not, but if it shows bad, it IS bad.
They seldom throw a code.
This is what I've always believed...
There is no battery voltage to the CKP.
The pulse is not a pulse but a constant a/c voltage produced by the ckp sensor itself
The drop in a/c voltage caused by the missing tooth tells the ecm what stroke the engine is on.
The only way to test the ckp, is to UNPLUG it from the ecm, put a multimeter on the 2 wires, (R/B and B) and crank the engine. it should show 1-5 VA/C.
This is NOT 100% reliable tho as some will show good when they are not, but if it shows bad, it IS bad.
They seldom throw a code.
#74
01-14-2024, 08:32 PM
@60Gunner I had the crank sensor unplugged and got a code when cranking engine, so I hope that none of the wiring up to the sensor is damaged. When I want remounting engine pinching wires was my worry, I don't remember touching the sensor but it's possible it got hit. Do you know if the voltage I got at ignition coil was good (11.5v on red)? I'll check compression again tomorrow to see if that improved and put oil in the spark hole like @paulmedford said. See if that bumps compression while both cylinders are still similar values.
That should be 12V at the coil. You could have a pinched wire or corrosion causing a voltage drop. Did you check the ground to chassis connection? Relays by the ECM?
Electrical issues can be a real bitch. Even harder online.
Last edited by 60Gunner; 01-14-2024 at 08:34 PM.
#75
01-14-2024, 09:05 PM
@60Gunner @paulmedford my battery 'should' have been at 12.5v... that's what gauge was reading but never bother to check it with multimeter. Was not wanting an electrical issue and of course that's what I get. I'll look at price of new sensor, charge battery and maybe get something better on the ignition coil but this is my new battery. Would really really cold weather drop voltage a bit? I'm grasping at straws here. At this point what would yall do?... when I did my audio system 2 years ago I got weird ground issues that threw bcm codes and it just sort of worked out if nowhere after undoing and redoing every connection and every screw damn near.
#76
01-14-2024, 11:07 PM
@60Gunner @paulmedford my battery 'should' have been at 12.5v... that's what gauge was reading but never bother to check it with multimeter. Was not wanting an electrical issue and of course that's what I get. I'll look at price of new sensor, charge battery and maybe get something better on the ignition coil but this is my new battery. Would really really cold weather drop voltage a bit? I'm grasping at straws here. At this point what would yall do?... when I did my audio system 2 years ago I got weird ground issues that threw bcm codes and it just sort of worked out if nowhere after undoing and redoing every connection and every screw damn near.
I've cut the connector off and made the wiring long enough to use. I might even have that one. I could send it to you if i do. Might have 2.
Sucks throwing $$$ at it to see what works.
Throw a charge on that battery first. 12.5 isn't good. Should be 12.8. 12.7 at least.
Sitting in the cold will drain them tho.
Last edited by 60Gunner; 01-14-2024 at 11:10 PM.
#78
01-15-2024, 09:03 AM
I would see if anyone i knew had a sensor I could plug in. They're all the same. Just different lengths of wiring to reach the plug in as far as I can tell.
I've cut the connector off and made the wiring long enough to use. I might even have that one. I could send it to you if i do. Might have 2.
Sucks throwing $$$ at it to see what works.
Throw a charge on that battery first. 12.5 isn't good. Should be 12.8. 12.7 at least.
Sitting in the cold will drain them tho.
I've cut the connector off and made the wiring long enough to use. I might even have that one. I could send it to you if i do. Might have 2.
Sucks throwing $$$ at it to see what works.
Throw a charge on that battery first. 12.5 isn't good. Should be 12.8. 12.7 at least.
Sitting in the cold will drain them tho.
I'll try checking voltage at ckp when cranking engine and see what I get.
#80
01-15-2024, 12:34 PM
Seasoned HDF Member
that's the weird thing and something thats confused me, ive been taking the batteries inside and charging them on a battery tender and I usually test them before taking them out and they DO read 12.7 or even 12.8v then when on bike it drops to 12.4v on the gauge. Got tired of lugging them back and forth so i left one in bike with battery tender hooked up.
I'll try checking voltage at ckp when cranking engine and see what I get.
I'll try checking voltage at ckp when cranking engine and see what I get.
If your close to 12v at testing point Your good to go.
if you all of a sudden see say 10.5 v at test point reck the voltage at the battery and go from there.
Most circuits I have dealt with and components will operate just fine at 10.5v, it's not great but still works
You can have 10.5 v as long as there is enough amp currant flowing
WP
Last edited by WP50; 01-15-2024 at 12:38 PM.
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paulmedford (01-15-2024)