[CalgaryHRV]

That is strange and not a commonly reported issue on this forum.

1st up for any modern vehicle is to scan the ECU for any DTC's.
For the HRV, monitoring battery voltage with some kind of in-cabin voltmeter is critical.
Just read all the HRV battery issue threads.

You mention that the issue mainly happens when it rains. Is there any evidence of water on the carpet, under the dash on either side of the vehicle?


Your EX HRV should have a push button start.
Many issues have been reported for that pushbutton, although the usual symptom is the HRV not starting.

I wonder if the push button start switch is acting up. Honda did issue a TSB/recall for it plus many other folks took the switch apart and cleaned it.

Have you looked into the push button start switch? TSB/recall and cleaning procedure?

 

[CalgaryHRV]

Going by your posts, it sounds like you are guessing, rather than a logical, step by step trouble shooting approach to the issue.
I hope this is not the case.

What is your voltmeter telling you about the battery voltage?
Your voltmeter will tell you if you need to replace the battery or not.

What is your OBDII scanner telling you about the ECU stored diagnostic trouble codes?
DTC(s) can point you in the right direction or to the exact issue.

Are you referring to a HRV Field Service Manual?

Trouble shooting automotive electrical issues without the FSM is very difficult even if you are a skilled automotive technician.
The HRV FSM is available for download with a google search.


A screenshot from the HRV FSM to answer your engine compartment relay question:

I hope you are able to resolve the issue.