Heated Grips - Keyed/Switched Line - Relay

So, I finally created a new little wiring setup to replace the broken one the PO had installed for heated grips. High and low (blue and white) wires from grips to switch. Red wire from grips to frame ground.

Red wire from switch to relay (blade 87).

Red/Yellow fused wire from battery to relay (blade 30).

Aftermarket connectors (orange-colored blocks on diagram) plug into the OEM connectors (white-colored blocks on diagram) for the license plate light (keyed/switched line).

Green (ground) wire from license plate is a pass through from OEM to aftermarket to OEM connectors.

Brown&Blue (powered) wire from license plate and to ground both connect to the relay (blades 85 and 86).

In theory, when the key is turned on, the license plate line should be powered, thus closing the high voltage switch in the relay so that the heated grips can be turned on. Key off, no power to heated grips.

That appears to be exactly what happens – key on, I can turn on the heated grips, key off, I cannot turn on the heated grips.

However, with the relay in place, the license plate light does not work (when the key is turned on, obviously). If I “jumper” the spade connectors (blue colored boxes on diagram) to bypass the relay, the license plate light works (or, if I simply plug both OEM connectors into each other, bypassing the relay entirely).

Unfortunately, electricity, accounting, and geology are three subjects that no matter how much I study, I can never retain any knowledge.

Is it possible that the relay is “consuming” enough voltage to the license plate light that there’s insufficient voltage left to turn the light on? I was thinking that the addition of the spade connectors in the license plate line added too much resistance, but as I said, even if they are in place and I jumper them with a short wire with two male connectors, the license plate light works.

Any and all assistance/advice welcome here.

 

That's not how I do it. I have the switched feed (from your licence light) connected as a T, then feed that to the relay 86 and the other side of the relay 85 going to the earth. I join that earth to the direct earh from the Hotgrips.

I don't touch the earth for the licence light at all. In my diagram I also had a voltmeter in parallel.

 

Thanks for this, but it doesn't answer the underlying question. On your diagram you apparently go straight to ground from the relay for the low voltage circuit. In my case, the low voltage circuit goes to the license plate light before reaching ground, and for some reason the license plate light will not work with the relay in place. I gotta be missing something...

 

The relay needs a ground (-). You can use power (+) from the license plate light to turn the relay on, but you can’t run it to both terminals. Follow Terry’s diagram without the wiring to the voltage meter.

 

Thanks. So as I'm understanding - the brown and blue switched wire to the license plate light has to connect directly to the license plate light (e.g., NOT through the relay), and I would have to tap into it (e.g,, splice a separate low voltage wire into the license plate wire , run it to the 85 blade on the relay and then run another wire from the 86 blade on the relay directly to ground. So while the previous owner's idea of using the connectors looks cleaner, the gods of electrons don't cotton to it. Thanks again!