Any ideas at this.point.would be helpful.. I am occasionally getting a loss of electrical power where.all.my.gauges will die and car sometimes stalls.. I got a p0685 code. Brought it.to.honda and they replaced the ecu under warrenty .. Prob stopped for about a week now its back seems like.its happening.when.the.car.is under a significant.electrical load lights radio ac on etc ..now tje voltage is reading 14.1-14.4 so i.know.the.alternator.is.working seems.to moastly happen when driving.down an incline but happens.other.times.as well ive tried cleaning off all the battery leads with a wire brush and testing.the.batteryas well .. The prob seems pretty intermitent but is annoying as hell .. I am.still.getting.the p0685 code.sometimes.but.it.gets erased as soon as the.car.shuts.off .. So needless.to say its not the.computer .. But.now the warrenty is expired so im gonna.have.to come.up with a solution on my own .. Any ideas? Anyone ? Please help

 

Just a SWAG but sounds like a wiring harness/grounding/contact issue once you've eliminated the ECU from the picture.

OBD2-OBDII Engine Light Trouble Code P0685 HONDA - Electronic Control Module Power Control Circuit Malfunction | Engine-Codes.com

 

Jeez .. So how do i go about.fixing that?where do i look or start? Of all.issues eletrical is def my.weak.point again.any help on.how to fix or where to start would be.very.helpful...

 

Electrical/Electronic troubleshooting (TS) is hard enough. Virtual TS makes it even harder. I'm not a Honda/Fit pro like others on here. Just an average DIY guy but do have some electronic/electrical background.

I think it would help to pay closer attention to the conditions when your intermittent loss of power occurs - what's on (car), road conditions, speed, rpm, how/when it (power) comes back on, etc. and post them with as much info as you can remember. This would help in analyzing the issue. You mentioned "while driving down an incline" and "others." Interesting... What would be the other conditions?

Visual inspection would be my 1st step - wiring harness, connectors, pins, grounding strap, etc. for anything obvious like loose connectors, frayed wires, burn marks, etc. Stay close to the main harness and ground points. Just my take.

Maybe some of the pros on here can chime in. Good luck and keep us posted.

 

ok so today I tokk the battery out and took the positive cable assembely apart including the 80 am fuse / relay located on the positive terminal and to my surprise it was extremely corroded not only on the terminal it self but on many other parts of the assembely as well I took time and sanded away every little piece of corrosion then air blasted it to clean everything up really nice took the ground cable off the car and al thought it wasn't really corroded I took it apart as well sanded it a little cleaned away the large amount alomast a teaspoon full of sand and debris that was behind the ground cable which connects to the body it self and so far the car has not done any of the described sypotoms I also unplugged and replugged every plug under the hood I could find just in case of a bad connection .. so im keeping my fingers crossed ill keep you posted

 

Hey did the code ever come back ? .. I know it's an old thread but I have same problem !!:/

 

NECRO BUMP!

I'm looking to see if anyone else is having this problem and how it was fixed. My problem is exactly as was described here.

 

It has all the steps for this code . Check the relays, that was my issue .
http://ww2.justanswer.com/uploads/acuramstr/2012-05-08_124957_p0687.pdf


QUOTE=RoachsRSX-S;1339623]NECRO BUMP!

I'm looking to see if anyone else is having this problem and how it was fixed. My problem is exactly as was described here.[/QUOTE]