Weird starting issues - starts sometimes and not others?

[StraightUpHippo]

Hey all,

So I've developed a very weird starting issue on my 172 after a failed sub install over the xmas break. For some reason, my car starts sometimes and not others, when it doesn't start I hear one click and the car fails to turn over. I've checked my battery with a volt meter and it's reading around 12.2v (which I understand is normal) so that leaves me with the alternator or possible fuses? I've noticed if I leave the battery unplugged and then go to start the car it works most of the time, never experienced anything like this before...

Was wondering if anyone could point me in the right direction? It's my daily so as you can imagine this has been a right pain!

Also a forum noob so bare with 😅

 

[StraightUpHippo]

Finally got this issue sorted, turned out to be the starter motor relay

 

[Fishfire]

Finally got this issue sorted, turned out to be the starter motor relay

Don't suppose you have a part number for the relay?

I'm having the same issues (new starter so defo not that)

Also.....which relay possition is it? I can't find a definitive "it's this one" picture anywhere 🤦