2016 Pete 587 Starter interrupt relay clicks with the engine off.

Sounds like a short in where the relay is plugged into. Short to power. Sometimes the relay receptacle gets so hot it melts. You have some functions operating with the key off when they should be key on only. Use a multimeter to check continuity between terminals of the relay with the key off. An owners manual should have a schematic.

 

Make sure you have the right relay. The driver or another tech could have installed it.

Otherwise...

If you replaced the relay and/or you're certain it's the correct relay, there's no need to check it (if you did you would bench test it, jump power to the relay to see it function. Make sure power is sent to the terminal where it's supposed to with key on/off. Key off it shouldn't be doing anything.).

I recommend (meant to say) checking the terminals where the relay is plugged in. Look for discoloration. Smell it to see if it's burnt. Power should not be "relayed" between the power in to an output unless it is switched on via the relay. Use a multimeter in the terminal box where the relay is plugged into. Make sure there is NO continuity between power in and an output. If there IS continuity, something likely melted or deteriorated between the terminals in the box (not the relay).

Again, an output doesn't receive power unless it is switched on, so there should be no continuity.

Re-reading your original post, the fact that it clicks every 2 minutes makes me think it's the wrong relay.

Starter Interrupt Relay Diagrams (the12volt.com)

 

So it sounds like the wire could be crimping, possibly inside the harness. You will have to isolate the wire and test it the length of the circuit (from the relay to the starter solenoid?). If it were me, and as long as it complied with the DOT repair policy, I would snip that wire and replace it. 25 ohms tells me that something is interfering with the wire down range. Wires in a harness create an electromagnetic field. You experience this when you run your speaker wires along side your amp wire and it creates that whining sound. They're finicky.

What you could do is, run a separate wire from the relay to the starter (essentially a long jumper wire). Don't run it through the firewall. Run it from the fuse bus to under the vehicle, to the starter. Same gauge. Test the ohms with that set up. There should be little to no resistance. If there isn't resistance, then you know the problem is with the original wiring. If so, you'll have to trace it to find the problem.

 

Since the key is off there will not be any power going to your starter (unless it's normally closed) until you turn the key on. If you're that uncomfortable, use a test light to see if power is going to the starter from your test wire prior to doing anything. Before that, check the output from the relay to make sure power isn't coming out with the key switched off.