I have a plx m300 that im using with s300j on a jdm p72. Im using an obd2a-obd1 conversion harness also. What I did was run the power and ground directly off the conversion harness. I called up hondata and the tech there said not to run power and ground for anything off of what the ecu uses for power and ground. I personally dont see why it matters. I used the solder butt connectors they sell at napa and am recording .2 ohms resistance on each wire, about the same as before the wires were cut and soldered. The connection is clean and tight. My answer to the tech at hondata was "Wouldnt circuit will run in a parallel , so should it matter ?" And he just said "Trust me dont run anything off of there."
Has anyone done this ?

 

the reason you shouldnt hardwire the wideband power and ground to the ECu because you dont want to draw power from it. Doing so makes the ecu have to work harder in order to perform its functions and can potentially be harmful.

When i reinstall my wideband i plan on running the power wire to the battery with a switch so its not powered when the car is off.

 

Thats what a few people are saying but if its in parralell it shouldnt take any power from the ecu. There should be 12v before the load on each leg of the circuit.

 

just giving you my opinion. I agree with hondata and many on pgmfi.org feel the same way.

 

yes i think they would also but doesnt that go against basic electrical principles ?

 

I've heard anecdotal stories myself of problems with taking power from the ECU harness.

I used power from the cig lighter, which does admittedly reduce its ability to do other things (added a tire pump, pop went the fuse), beyond that it works well enough.