Battery voltage

[Boyle.r]

When logging in Kpro my battery voltage is fluctuating between 12.5-13.2 volts but upon checking voltage at battery using a volt meter it's holding a steady 14.2 volts so alternator seems to be functioning ok. My first taught was bad earths so checked all those and even ran a large jumper cable direct from battery to earth of engine harness and still the battery reading in Kpro was lower than actual battery voltage. Any ideas?

Car is a K swap DC2, I have wired it up as per your diagram used in race car. Only thing I noticed is, there is no mention as to where pins E3(LG3 Logic ground) and E4(SC3 sensor ground) should be connected, I assume these need a earth from somewhere?

[Hondata]

Do not connect LG3 or SG3 to anything (they normally are used for the FTP).

Do not add any extra grounds. There should be transmission to body, main harness to engine and engine timing cover to body only. Remove and clean the grounds so the lug in on bare metal.

Use a voltmeter to narrow down where the voltage drop is and/or current flows on the grounds. See http://www.hondata.com/techk20swapgrounds.html

[Boyle.r]

Thanks Hondata.

I'm thinking perhaps the fact my main power feed to ecu etc is also powering the relays for fuel pump may be the problem? Which pin at ecu should have constant 12volts?

[Hondata]

No pin at the ECU gets constant 12V. The ECU gets all its power from the main relay energized circuit.