So... anyone know what this wire is for? Corolla ZZE122 wagon engine bay

[Sick Puppy]

HI everyone, hoping someone may know what this wire is for.

Took it to mechanic a while back, normal service, but also suspension and steering gear replacement too. Mechanic has since ceased trading due to health issues.

Car has been running fine, but when I opened up bonnet, found this. Haynes book sheds no light. I'm going to take engine cover off to have a better look. Any pointers appreciated, thank you for reading!

[Hiro]

I assume you mean the wire/ring-terminal just to the right of the washer bottle?  Most likely a ground, when my wagon re-appears this weekend I'll confirm

[Sick Puppy]

Thanks Hiro, much appreciated 🐵

[Hiro]

Yep, ground wire for the head, the ring terminal goes on the rear-most bolt of the power steering reservoir bracket (which would make sense, since you said the steering gear has been replaced)

[Tony Prodigy]

Upon first glance,  it's a ground wire because those black wires with a circular connector are usually ones where it can and should to bolted to something. Looks like your mechanic missed this somehow. 

[Sick Puppy]

Hiro, you are my... hero 😋 Seriously, thank you very much! Sorting it now, once I get it out of the rain

[ChrisH073]

Looks like the earth wire that goes onto the bolt that hold the power steering reservoir bracket.