Having installed an EFI Technology X2 ECU, but using stock ingition swtich and relays. Relays are now buzzing or rattling when the engine is running. Is the problem with the Immobilizer or the relay circuits?

I would think the relays? Needs some heavy duty internals. That is the buzz, right? You might change that out to the other type relay. Like a horn relay. The one that has the [86 87 85 30] block kind of numbers? You can find a few wire hookups, switching around the relay prongs to do different things.

I'm the last to ask about electrics. I guess at it. There is a logic to it, but that takes common sense. Short (pun) on that... Long on noise < (pun) that too.

I found out the issue. I had removed all the fuses for lights including the fuse for the lighting relay. When that fuse was installed the relay worked fine.

Glad you got that figured out.

I've got a bunch of new relays on mine now. Two for the electronic cruise control alone... one to tell the cc that the brake has been applied, one to turn the Engaged light on and off.

Then I've got one for the Stebel air horn.

I don't have one for the Denali D2 LED driving lights, because they don't draw more than 10A on startup at 100% intensity, so the Dispatch 1 Electronic Fuse box can handle them directly.

Then I've got two more in back, one for the rider's heated clothing, and one for the rider's heated seat. They are wired directly to the battery (I ran a + wire and a - wire back there for them) and to the auxiliary switched +12 lead in back so they know when to disable themselves.

So 5 new relays. The air horn one will click everytime I use the horn, and the rider's two will click when the bike turns on. The cc pair will click everytime I touch the brake and everytime the Engaged light is toggled off or on.

But I won't hear them, they aren't loud enough under normal operation to be heard being buried under the seat or up beside the left front wire boot.