2012 Fit Sport MT. 140K miles (or thereabouts)

Today we were cruising at highway speed and the battery light came on. A minute or so later the Power Steering light came on and I lost steering power assist. Air bag light came on as well.

Pulled over. Shut down. Checked under the hood. Belt looked OK. Nothing obviously wrong with the terminals on the battery. Got back in and turned the key on. Instruments came on but we only got a click when I tried to start. I bump-started it (Manual Trans FTW) and drove home. On the drive home...we had a few minutes of surface streets at fairly low speed. The failure/warning lights gradually went away. We got back on the freeway and all was well for a few minutes. Then the failures started again. First the battery light. Then PS light and loss of steering power assist. Then airbag. Eventually we also lost ESC and ABS. Then even the clock went dead. Fortunately we were almost home by that point.

We got off the freeway and had about a 2 mile drive home on surface streets. The clock came back while we were waiting for the light at the offramp and one by one everything else came back as we drove home. By the time we got home, everything was working and the battery light was off. Parked in the garage, shut down, then tried to start...it fired right up.

To me this seems like a charging system issue...under the load of high speed (freeway) driving, the charging system couldn't keep up and as battery voltage dropped, the computer cut power to the unnecessary systems. Back at low speed/low load, it was able to recharge enough that the computer brought everything else back online.

I'm going to check the obvious stuff like battery terminals (They looked OK, but I'm going to check them more thoroughly) the ground strap from the battery to where ever it goes, and the wires on the back of the alternator.

If all of that seems OK, I'm guessing it is probably the alternator...but I'm open to other alternatives and/or troubleshooting steps to help verify the issue.

And...how big a deal is is to replace the alternator? It looks fairly simple: Disconnect the big wire and the small wiring connector. Remove the belt. Unbolt the alternator and remove. But...I just took a quick glance, so I don't know if there's some hidden gotcha like you have to take the engine out and remove the tailgate glass to get to it.

Any thoughts/advice/tips would be appreciated.

FWIW, so far this is the only thing that's gone wrong with the car in 140K miles. It gets driven hard every day.

 

Why don't you get a voltmeter and plug it into the accessory receiptical. Now you can watch the alternator as you drive. They are anywhere for $3.00 out of China to under $20.00 for a US one. Walmart use to have the Innova 3721 one in the area were they sell batteries. I haven't looked for one in a few years but I assume they still sell them. Harbor Freight also has them. I happened to notice one when I was there today.

A fully charged battery with the engine off should be around 12.6 volts. An alternator normally runs around 14.0 volts with the engine running. Honda has something called ELD (Electric Load Detector). It will scale back the charging voltage when the computer thinks your battery is near full charge.

I'm not trying to talk you out of cleaning up battery cables or checking the battery but in reality your car runs off of the alternator. The battery is simply a storage device. The problem with removing the battery in today's cars is you are never quite sure what the computer will do if it is not there. In earlier cars you could remove the battery after starting and it would run just fine.

Back on the ELD. Have you installed any aftermarket devices that consume power? If you did and did not attach the power source for the device AFTER the ELD, then the ELD will not detect it's power usage and will under charge the battery.

One other thing that people overlook is a slipping belt on the alternator. If the belt tensioner is loose or bad it will cause the alternator belt to slip and not charge. A very hot pulley on the alternator is a sure indication that the belt is slipping.

Al of the above said, My best guess is that you have an alternator or ELD problem.

Universal Digital Car Battery Engine Voltage Meter Monitor Tester Voltmeter-4.31 and Free Shipping| GearBest.com

 

Freeway driving doesn't have any significantly higher electrical load than local driving, and the alternator produces a lot more power when the engine is in the power band than when it's idling. (If anything, highway driving has lower electrical demands—the radiator fan isn't running, the brake lights aren't in use as much, there's less power steering assist, etc.)

It does sound like something is awry with the charging/electrical system. Checking for a slipping belt sounds like a very good idea.

 

Multimeter shows high 13's at idle, but it starts dropping if you rev the engine.

I'm not finding any evidence of a slipping belt...the belt feels tight, the pulleys are not hot, etc.

The local O'Reilly plugged in their tester and it showed everything good...but that was at idle.

 

I agree that the alternator SHOULD be producing more power at freeway speed than at idle, but my multimeter shows that is not the case.

 

Update: When I apply electrical load to the system by turning on the high beams, AC, rear defroster, radio, and the fan on high, it is making less than battery voltage...around 11.8 volts.

I'm going to swap the alternator and see what that does.

 

definitely its the alternator.

 

HOW THE EFF DO YOU GET THE DAMN BELT BACK ON???

I've replaced serpentine belts on Ford, Dodge, Jeep, and BMW. This seems prett y much the same...route the belt around everything except the alternator pulley. use a 19mm wrench to pull the tensioner all the way up. Slide the belt over the alternator. Release the tensioner. Have a beer.

I've been at this for almost 2 hours. I tried going back to the old belt, just in case the new one is shorter...same issue.

It just seems like there's not enough slack, even with the tensioner pulled all the way against the stop.

What am I missing? It can't be this difficult.

 

here u go buddy

 

Yup...That's what I was doing. Even with the tensioner up against it's stop, the there wasn't enough slack to slip the belt on.

I did get it, though. It wasn't pretty, but whatever.

I ran a ratcheting tie down from the 19mm wrench attached to the tensioner up to a hook in the rafters of my garage. Cranked the tie down until the tensioner was on the stop. That left my hands free and I used one hand to guide the belt onto the alternator while the other hand used a socket wrench to turn the alternator pulley to suck the belt on.

Once the belt was on, there was plenty of slack,but getting it up over the outside lip on the alt pulley was not happening.


The good news...once I got the belt on, the rest of the job went quickly. The car's back together now with the rebuilt Alternator and is charging at 13.6v at idle with the AC, fan on max, high beams, rear and rear defroster on. So It looks like the Alternator was the issue.

I'll post some more details later...hopefully my experience will help the next poor schmuck who has to do this. This job was way more complicated and difficult than it needed to be.

 

So...details...

I don't have a service manual for this car (yet. I'll be fixing that problem soon.) so I don't know if this was the best way, but here's how I did it.

The alternator comes off very easily...just remove the belt, then the two mounting bolts, two connectors, and the little 8mm bolt for the wire hanger. The problem is there's not room to get it out of the engine bay.

It looked like I could either remove the intake manifold, or the radiator fans. I chose the fans.

I removed the battery, airbox, coolant expansion tank, and both fans. I also removed the bolts and brackets which secure the top of the radiator so that I could tip the radiator forward a bit. And I removed the upper radiator hose from the radiator. (Secure it up high so that it doesn't dibble coolant on the floor while you're working.

At that point I was able to get the alternator out...it was a tight squeeze but came out fairly quickly.

I also wound up removing the splash guard. this make it easier to route the belt. It might not be strictly necessary but it's pretty quick. If you do this, make sure you have some of those stupid miserable clips that secure the splashguard to the car since they often fall apart.

Putting it back together...I put the alternator in and secured it's mounting bolts, wiring, and the wire hanger, and then set about putting the new belt on. This part was a real bastard, though once I figured out my trick, it went on quickly. Having another person there to hold the wrench that pulls the tensioner up would be nice...but you'd have to be careful not to get in each other's way. Since I just used a tie-down, that wasn't a problem.

Once the belt was back on, everything went back together pretty quickly.

Plan on having to replace a few of those little push-mount cable ties since they often seem to break when you remove them. Or just replace them with regular zip-ties (which is what I did.)

The job is much harder and complicated than it needed to be because of the crap you have to remove to get the alternator out. I think the shop bills 1.5 hours. It took me closer to 4 hours, but a bunch of that was trying to figure out what I needed to remove to get the alternator out and then struggling with the belt. 1.5 hours is probably legit if you know what you're doing and/or you're reading from a service manual.

 

I'm having the exact same problem. Figured it was the alternator. Did you get yours rebuilt or buy a new one? If so, from where?

 

Check fuse #12. If it keeps, poping it is wire harness between MAF and fuse box. Just had happen to me. Alternator will not work for me. Did replace alternator, but same thing. Going to replace harness soon.

 

Update: found the source of the issue. Second O2 sensor cable has been rubbing on exhaust and finally exposed wires. This caused the #12 breaker to keep tripping.