Russ' Do It Yourself Home Workshop

Finding Fixes to Just About Anything and Everything

Installing an Engine (ICE) Hour Meter on a 2018 Honda Clarity PHEV

Posted by Russell Wright on June 29, 2019

Love my Honda Clarity…and we also own a Prius Prime.  The Prius has lots more tech than the Honda, especially when it comes to monitoring the operation of the ICE (Internal Combustion Engine).  One of the simple upgrades is to install an engine hour meter so you can really keep track of how much the ICE is running.  This is most important for maintenance reasons.  And, if you’re concerned about the environment and don’t want to “over oil change” it is also a way to make sure you don’t throw out completely good oil.

Following the advice of KentuckyKen on the InsideEVSForum I purchased a low cost hour meter on eBay.  Shipped from the US, mine cost $6.98.  I purchased another from Hong Kong for $4.47.  I figured I’d do one for the Clarity and then try one for the Prime.

While there was a part of me who wanted to get a mechanical hour meter, I determined that not having to find a 12V wire that was energized when the ICE was on was a benefit of using one of these self-powered meters.  There is no power required as the meter has its own internal battery.  When it runs out, I’ll just buy another.


Here’s how it came.  Now to connect it to my snowmobile…oh, I live in Texas…I mean my motorcycle.


The package contents, unpacked.


The installation instructions.


For a mounting location, I like the plastic cover over the wires.  I think I can use the short screws through the meter to attach to the plastic cover without damaging anything.


The meter is just the right size to fit there.


See how it will look when installed?


Let’s remove the cover to expose the spark plug coils.  The cover just snaps in place with rubber grommets, so just pull upward to remove.  Here are a couple of pics to show you what the part looks like.



Now we have the coils exposed.


The easiest way to do this is to remove the coil.  Start by pressing the tab on the connector near my thumb end and gently pull on the sides to disconnect.


The coil is held in place with one 10mm bolt.  Simply remove it and pull up to remove the spark plug coil.  For all you old-timers, remember when there was one coil with spark plug wires running all over the place?  Now the low voltage wires are run to the individual coils and it makes for a much neater installation.  This EE loves me some electronics!


Here’s the fully removed coil.  So simple and elegant.


While you have the coil removed you can wrap the wire around it.  Try and keep it up off the seal.  What will happen is when you reinstall the coil you’ll find the wire is snugly compressed and, at least on my installation, it doesn’t appear to be going anywhere!  Be sure and leave enough to connect to the meter.


This is a little hard to see, but the wire just slips into the slot in the back of the meter and is held in place by compression.  Use a small screwdriver to shove it in place.


So here it is installed and I’m testing it.  Already have 0.1 hours (6 minutes) on the meter.  Had to run it around the neighborhood in Sport HV mode.


And here we are with the screws installed.  I’ll remove this in a bit and make sure the tips of the screws are not causing any issues.



Now let’s get out the label maker and put a label on it so those folks peeking under the hood will (hopefully) understand what it is.


After running around for a bit, punching it in Sport HV mode to get some hours on the ICE.



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