Hondata

I am having a similar issue to a previous user at this link viewtopic.php?t=23269 Where his voltage shown on kmanager is not the same as the voltage as what is on a voltmeter. Testing from the positive battery post to the ecu show a steady voltage whereas the voltage for battery shown in kmanager is erratic. I believe my alt is not charging properly which makes be believe its going bad but this issue has always existed even when the alt was outputting 14.5v.

From the positive on the battery to the ecu/alt/fusebox and everything I could find was a steady 13.87 with the fan off and about .5 less with the fan on. The kmanager never makes it over 13.5 and often dips down under 12. Compared to another user on k20.org my battery graph looks terrible. The issue is that it has always looked this way even between new alternators and batteries.

I have checked all my grounds from the positive battery post to each ground and they all have the same voltage to the T and it is steady:
Timing cover to chassis
Harness to valve cover stud
Trans to chassis

My battery is in the fender and grounded to the chassis as well. Not sure what I am missing. Is it normal to see such an erratic battery reading in kmanager?

PRB
Serial 55835

Forgot to post my files.

Just did some more testing and I think my battery must have just been low from sitting. I now get a 14.10 v reading from the alt after charging the battery.

Fan off or on made very little difference like .001-.005 difference.
battery + to alt 0.37v
battery + to ecu 0.27v
battery + to inj 1/2 0.26v

I ran a dedicated wire from the battery to the conversion harness to power the ecu rather than through the oem fuse box and the voltage is much more stable in kmanager but it still never seems to go above 13.5 despite the wire itself providing full voltage and the ecu plugs reading full voltage as well on A2 and A3.

You should have the alternator tested.