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2013 Touring with about 90K miles. About a month ago, after sitting in the garage for a week, the lights would come on, but not enough juice to turn over the engine. Charged it and everything is fine for a couple more weeks until... once again... couldn't turn her over. So I charged it up yesterday and did the parasitic drain test today. I'm getting about .04 amps draw with the multimeter bridging the negative battery terminal to the disconnected negative cable and everything off. Then I reconnected the battery and tested voltage across several fuses and found that fuse #23... "Backup" ... was giving me a voltage reading. So I pulled that fuse and again disconnected the negative terminal and amperage draw is zero. So I know that something connected to #23 is the issue. Now I'm here asking if anyone is aware of any common issues related to this circuit that I might look at before I bring it in and cough up the cash to have the Honda guys take a look.
 

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2020 Honda Passport Touring AWD Metallic Steel
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Depends, which fuse box? There are 4 in the 13 Pilot Of which two have a 23 fuse. The main under hood fuse box 23 circuit would be the backup lights. I would suspect a chafed wire somewhere. The under dash fuse box 23 is the circuit for the STRLD circuit which is part of the electric power steering controls unit. On that one I wouldn’t hazard a guess.

FYI Honda abbreviation cheat sheet. RJAAI001_acronyms.htm
 

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Discussion Starter · #3 ·
It is fuse 23 in the triangular fuse box under the hood. It is labeled "Backup" but is definitely connected to more than backup lights. For example, when I start the car with the fuse removed the nav/radio display does not come on.
 

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Please let us know what was the problem and solution. Thanks much.
 

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Under-hood Fuse 23: 10 A Active noise cancellation unit ( + B)*4, Audio-HVAC display unit (+B)*7, Data link connector (DLC), Front HFL-ANC microphone*9. Front HFL-navigation-ANC microphone*4, Gauge control module (VBU), HandsFreeLink control unit ( + B)*8, Immobilizer-keyless control unit (VBU), MICU (VBU), Power mirror control unit (VBU)*2, Power seat control unit (VBU)*2, Power tailgate control unit (VBU)*1, Door multiplex control unit (VBU)*10, Rear controller and screen ( + B)*3, Navigation display unit ( + B)*4, Audio display-USB adapter control unit ( + B)

Lots of qualifications depending on trim level of course.

Under-dash Fuse 23: 7.5 A PCM (STRLD)

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Forty milliamps (0.040 Amps) is the normal resting draw for the car. The "backup" designation is the keep-alive power for the learned parameters in the PCM (engine and powertrain control module), and a few other smart accessories. FWIW, a new battery has a rating around 65 Amp-hours of capacity. The actual definition of that capacity suggests that there probably won't be enough left to start the car due to low voltage, so "useful" capacity will be less. So, divide 65,000 by 40 to get rated life in hours with that drain, and you get (drum roll please...) 1625 rated hours. But you want to have enough capacity left to start the car, so the real useful life is well under half of that new rated life. Each time you dip the terminal voltage below 10, you sacrifice a fraction of the remaining available battery capacity. So at this point you have less than 65 AH, and it's a slippery slope down from there as each drain or engine start dips voltage into that derate zone below 10.

My normal maintenance protocol includes an annual check of the specific gravity of the electrolyte (fluid) in the cells. The basic tester is a few dollars at your local parts store, and looks like an eye-dropper with colored balls inside. Draw a sample from each cell and see which balls sink. It's acid so use gloves and glasses. Start shopping when one ball sinks, start buying when two sink in any cell sample. Battery needs to be fully charged, plus 30 mins resting after charging, for the test to be valid. Winter is the toughest season for our Pilot, so it gets all this done in the fall. Investing in a battery before the old one fails has a payback the first time it would otherwise have stranded me, even in my own garage.

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So what to do now... If the battery is over four years old, it's quite likely due for replacement anyway. Five years is about the max reliable life in normal duty.

In these days of less driving, folks would do well to connect a battery maintainer when they know the car won't be driven for a week or more. Mine sits for most of the non-winter season, when a maintainer from one of the non-winter cars normally gets moved to the Pilot. I've been rotating one from a non-winter car that has the battery completely disconnected while it's stored, but have a couple more of the maintainers in my Amazon shopping cart; K's 4-runner is in the duty rotation too.

I've settled on the CTEK 7002 as my weapon of choice here at the dr bob world headquarters maintenance shop, but there are many acceptable options at lower $$. My local Costco usually carries a small Battery Tender at around $35, alternating with another one with a brand that escapes my feeble brain at this moment. A regular "battery charger" will cook the battery, so shop for a "smart" maintainer. Regardless of which maintainer you choose, connect it as soon as you park the car and don't anticipate use for the next few days. A good maintainer will extend the life of the battery a lot, plus it helps with alternator life too.
 

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Under hood is also causing me to have an amp draw that leaves the vehicle to not start after approximately 36 hours of not being started. Testing with my multi meter showed a 3.4 mv draw across the fuse. To my ability this equates to a .5ma draw. Since this circuit performs hands free linking I wonder if the proximity of my wifes phone to the vehicle while parked is causing the system to detect and try to activate? Any thoughts would be welcome.
 

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Move the phone out of range or shut it off and repeat the test. You will have your answer.
 

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Trying to guess current flow through a fuse based on voltage drop is just that, a guess. Measure the current flow with a meter intended for this purpose.

Some searching here will guide you to some popular causes, like the AC clutch relay. The clutch circuit really needs a suppressor diode, but instead has a tendency to arc when it opens. Over time the arc flash metal will cause higher current drain and run the battery down for you while parked. You can do a lot of testing, or just replace the relay.
 

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Thanks for the discussion, the phone has bluetooth turned off so not likely my first guess. I have already replaced the AC Clutch relay but the problem persists. Any further suggestions continue to remain welcome.:)
 

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Other than what Xtrac said, has anyone found out a fix for their issue? Been having an issue similar to this, and its not the ac clutch relay or hands free. Did Tony A the poster find a fix?
 
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