Main relay replacement (What if you need that relay now?) - Honda CBR500R Forum : CB500F and CB500X Forums
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post #1 of 6 (permalink) Old 11-05-2019, 02:57 AM Thread Starter
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Main relay replacement (What if you need that relay now?)

A few weeks ago I started having no-start problems with my 2015 F, starter would chug along but no ignition. It got cold so my first thought was voltage drop from a cheap-o battery, did a simple load test and it failed miserably so the battery was replaced. Then it didn't start again. This time, I inadvertently ran the starter long enough to get some DTCs, two codes for injector voltage. Went through the service manual and all the electrical diagrams, discovered that that code could also be for a failed main relay as they're the only things on that circuit with ECU diagnostics.

There I was, in need of a relay. I thought it would be a simple thing, just call my local powersports parts department and get one. No. Not in stock, 5 days to order and get there. Ok, so what about an auto parts store that sells motorcycle parts. They don't sell them. Bulbs and batteries, that's it (if you're lucky). Amazon? They have it but no Prime shipping, ends up being sold by a company that waits 4 days to put it in the mail (wooo). Finally received it, replaced it this morning, and the relay seems to work fine.



Well what do you do if you need a relay? I had to scramble with getting some maintenance done to my car because the motorcycle is my daily transportation. I'm lucky though, the motorcycle isn't my only vehicle and I was only a few miles from my house when it gave me grief. I set out to find a replacement that isn't a powersports application.

The relay is a Micro ISO type, one of the most common relays used in cars these days. It's also a normally-open, single pole single throw relay, which makes it the most common configuration. But it's resistor-protected, which makes it tricky. The manufacturer is Panasonic (NAis). The part number on the relay is ACV31212-M11, which the manufacturer explains all but the suffix "M11". Here's some bad news, you won't find a replacement that costs what the OE relay does, about $8 USD. But, a horn relay from a 2008 Subaru Impreza is also an ACV31212 relay from NAis, though it has -M05 on the end (for reasons unknown). If you're stuck somewhere without a powersports place and you cannot wait around for a week, that might be your best option.

I will be purchasing one of these horn relays, with the intent of testing for coil resistance and etc. I will also attempt to contact Panasonic (NAis) to determine if the suffix denotes a different specification, or just batches them into different manufacturer part streams. My best advice is to purchase an OE replacement relay before you need it, keep it under your passenger seat or any storage you have. This is quite honestly a dumb issue to have, and I'm disappointed in Honda for not just using a relay that's in their automotive parts bins, because some of them are very close in specifications but I'm not comfortable using them without more data and interchange information with other parts. Panasonic is surely fine, but if it were a Denso relay then cross-referencing a replacement would have been much easier. Maybe that's why they didn't...

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Last edited by phatcyclist; 11-05-2019 at 03:22 AM.
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post #2 of 6 (permalink) Old 11-06-2019, 12:32 PM
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They dont because ALL motorcycle parts have inflated prices for increased profits!!
It might be the same and used elsewhere, but they then put a different PN on it and charge a higher price!

AND why would you think a starter relay would go out so often that you would have to carry one around with you?
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post #3 of 6 (permalink) Old 11-06-2019, 09:03 PM Thread Starter
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Quote:
Originally Posted by jdock View Post
They dont because ALL motorcycle parts have inflated prices for increased profits!!
It might be the same and used elsewhere, but they then put a different PN on it and charge a higher price!

AND why would you think a starter relay would go out so often that you would have to carry one around with you?
I doubt that this new one will go out soon, but there are three of this type of relay on the bike, used for the cooling fan and fuel pump as well. The starter relay and flasher relay are each different types, but the starter relay has been in use for a long time on Honda motorcycles, so getting one of those is probably not too difficult. I may keep a spare around though, if I can get them cheap enough and knowing at times a part like that could be a week away.
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post #4 of 6 (permalink) Old 11-07-2019, 09:03 AM
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That's kind of like saying
I need to carry a new engine with me in case I blow this one up.

Sorry I just dont get it, but yea keep one at home.
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post #5 of 6 (permalink) Old 11-07-2019, 11:15 AM Thread Starter
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Quote:
Originally Posted by jdock View Post
That's kind of like saying
I need to carry a new engine with me in case I blow this one up.

Sorry I just dont get it, but yea keep one at home.
Not really a good comparison, a relay is $8 and barely the size of a walnut; Keeping one somewhere on the bike is cheaper and easier than a $200 specialty tow back to your house. I guess if you don't rely on your vehicle for daily transportation, it's not something you'd put much thought into.
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post #6 of 6 (permalink) Old Yesterday, 08:09 PM
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Thank you, Phatcycyclist, that was a masterful bit of detective work and a tutorial on "how to". A prime example of why these forums are so invaluable!

Ralph

"You don't stop riding because you got old...You got old because you stopped riding,"
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