brucepick

Any hints on setting up an Alternator cutout switch for Gen 6?

A connector pinout would be good to have.

I don't want to just yank the connector. I want to be able to electrically disable the alt while driving (say under heavy throttle or a hill climb) and bring it back on when less load on the engine.

Yes my HX has plenty power but its an mpg project car. I drive 50-55 mi. to work each way and it doesn't need to run the alt at 13.x volts the whole way, as long as I'm not running a bunch of accessories.

brucepick

bump

Former User

MrMike

This is a good idea. Let us know how it works out once you figure it out. I'd say you'd pick up 3-4mpg losing the drag the alternator puts on the motor.

grumblemarc

iTrader: (4)

Until you forget to flip the switch one day.

NotAJDMFanBoy

The system is going to keep the battery charged at like 12.5 volts. Would running the alternator at higher load, increasing the drag more but for a shorter period benefit?

I know I heard not to run an alternator without the battery attached. Something about how the electricity has to flow somewhere and without anywhere to go it will damage the alternator. This is probably what you're trying to fix I assume?

brucepick

One thing I learned is that the ELD (Electrical Load Detector) plus ECM do cut the alternator electrically when certain conditions are met. Basically, that is: low electrical load, including headlights must be off, speed below 50 mph (rpms seem to have no effect), and engine not in fuel cut mode (coasting in gear with foot off gas).

[EDIT - correction: It may instead run the alt at a lower voltage, somewhere between 12.0-12.5. Watching the voltage on a digital gauge, I can't tell if it's totally cutting the alt or running at lower voltage.]

Supposedly it does this by grounding the white/green wire going to the "C" connector. I just haven't had time to chase it down and try it. Not sure if I really want to go grounding a wire with voltage in it though...

HondaPartsHero

Ignore the 3 pin diagram unless yours is a Canadian model with this style.

fleabag

Funny thing.... If you want to improve your fuel economy without removing the alternator belt, might I suggest you get a battery tender and charge your car? I discovered that putting my car battery on a battery tender improved my fuel economy by around 10% since the car didn't feel obligated to charge the battery like it did previously. Your idea won't save you fuel because the car will still try to charge it one way or another. Letting the alternator float charge at 13.5v will protect your battery. It's not the voltage but the amperage draw that increases your fuel consumption.

brucepick

Thanks to RonJ@HT and to HondaPartsHero for the diagrams. I will try put a switch in the line between Fuse 15 and the alternator. Black/white at the fuse, black/yellow at the alternator.

Sorry - I can't decipher the OBD2 pinouts above. Don't know if my car is OBD2A or OBD2B. Messing with the ECM/PCM connectors scares me. Lotsa wires in a small space. But I might be able to access the wire at the underdash fuse panel.

To those discussing whether it will save gas, and should I charge it from an outlet etc...
Yes I'd charge it from an outlet if running for any significant time without the alt. Will cost a few bucks though - my nice automatic charger disappeared from the garage, so I'll need a new one. Dang.

I don't doubt that doing this right will save fuel. Not huge amounts, but I've been doing a lot of little things and they all add up. Been getting 47-48 mpg in CT, USA in November. Got a solid 50 through the month of September, much nicer weather.

I also want to run the headlights off a second deep cycle battery because I run the lights nearly always in winter. I figure a decent size Optima yellow top, fully charged from a/c, would power the headlights for a good three hours. Doing that will take that load off the alternator, and when appropriate I can cut the alt completely. I can charge it up overnight.

California98Civ

I'm on the same road with you, brucepic. I just sent a PM. I started a thread on this same topic, not realizing you had too. I searched threads but I was looking for a "kill switch" and this uses the word "cutout" -- same thing but different words maybe hid the post when I searched. Anyway, I'll execute this mod on my 98 DX probably this week and then post back about it.

And kudos to RonJ@HT for the diagrams!