Optimax Voltage trouble?

[Cawagu]

I have a 2013 Optimax. I get a voltage drop and alarm on the initial startup of the day. The Voltage before I launch is 12.8V at the battery. I have watched the voltage drop to 9V on smartcraft when cranking. Once running, the voltage climbs to above 14V.
I have changed batteries twice and am currently running an Interstate 31, with 1150 CA.
The battery is showing 12.8V on the terminals at rest. The voltage drop is to 11V while cranking at the battery terminals, but drops to 9.8V at the engine when cranking. I changed the battery cables due to the difference in drop from the battery to the engine, but still getting the same readings with new cables.

Any help.......What's next????

 

[schematic]

where are you measuring it at the engine? The ECM complains when its voltage is below a threshold. The ECM is supplied voltage from a relay then through a fuse panel. A tired relay will not show up if you are measuring the voltage at the starter solenoid...

 

[Cawagu]

Thank you for responding. You have me somewhat excited because it appears maybe I'm not measuring correctly.
I am measuring with the black lead of the meter on the engine ground and the red lead of the meter where the positive battery cable connects just before the jumper wire goes to the starter.
Where should I be measuring from?

 

[schematic]

If you want to see what the ECM is getting, you have to measure at the ECM. Try checking the voltage at the ECM fuse while cranking. That will be a much more accurate reading than at the starter terminals. Voltage at the starter sounds OK, but that doesn't mean the voltage getting to the ECM is. A relay or related wiring could be adding excessive resistance, upsetting the ECM low voltage alarm.

 

[schematic]

G'night

 

[Cawagu]

Please bare with my ignorance, but does that mean I may have a blown fuse/relay that's causing the voltage drop or are you saying that the ECU is potentially bad?

 

[schematic]

voltage is supplied to the ECM via a relay. The relay may be bad, causing a voltage drop. The ECM complains of low voltage even though the battery is good. Checking the voltage at the fuse while cranking will give an indication of what the relay is supplying to the ECM fuse. If its low, you have to find out why. It could be the relay, associated wiring or poor grounds.