•300/500 2017-19 – “square” connector in headlight bucket on right side.
•300/500 2020-up “common” 3.9/4.0 mm bullet connectors that are wrapped in tape below the speedometer.
•1100 – under the seat.
Accessory power connector is switched on all models.
•2023 uses 08U70-K2Y-A00 which has the relay; max power available 1.0 Amp or 14 watts
•2020 to 2022 uses 08U71-K87-A30.
•2017 to 2019 uses 08U70-K87-A00.
•2023 relay only is 38501-MKP-DN1.
•2020 to 2022 uses 08U71-K87-A30.
For these two (2020 to 2022, and 2023-2025) you DO NOT NEED the 08U7x kit unless you want the lighter plug. Your accessories will connect without it.
•2023-2025 uses 08U70-K2Y-A00 which has the relay; max power available 1.0 Amp or 14 watts
•2017 to 2019 uses 08U70-K87-A00 – you DO NEED this kit to connect your accessories.
Power and Ground connections: For the 2020-up 300/500 models, remove the black tape from the 3.9/4.0 mm bullet connectors (female +, male -) that are below the speedometer, and plug the power and ground wires here.
Power and Ground connections: The 2017-19 300/500 models have an accessory power connector in the headlight bucket on the right side. Looking at the right-side connectors, it is second from the left – I believe the first connector on the left is a blue connector. After connecting, put the black plug cap in the remaining connector (the larger of the two) .. OR you can use the connector for something like driving lights. If you don’t buy the proper plug, you can use two 2.8mm spade female connectors. 2.8mm is the inside width; if the outside width is 3mm, you can re-use the blank plug to hold the two connectors. The ones I had were an outside width of 4mm, so I just used them without the blank plug as a shell, and they worked fine.
Not confirmed, but I believe the connector below fits the 2017-19 Rebel 300/500.
Rebel 1100 – the optional accessory circuit (OP) wire/plug is under the seat and is connected to the USB charger.
The OP circuit is switched and protected with a 10A fuse
Connections: (See below) Connect your Positive wire to the R/Y 12v(+) wire and your Ground wire to the BL ground (-) wire.
ACCESSORY SOCKET
P/N 08U70-K87-A00
CMX500/A
CMX300/A
No. Description Qty
(1) Accessory socket 1 – like a cigarette lighter – 1 amp max
(2) Sub-harness 1 – this plugs into the accessory plug in the 2017-19 300/500 headlight bucket
(3) Wire tie 1
(4) Socket stay 1
(5) Washer 2
(6) Collar 2
Below is the “square” connector for the 2017-19 Rebel 300/500 
I think this one does NOT fit:
2017-2019 Rebel 300/500: “The connector itself seems to be (don’t take my word for it) a Sumitomo HM 090 2 pin 6187-2801 and 6187-2451(2804?) which can be found on AliExpress and at corsa-technic.com and cycleterminal.com.”
For the location of the 1.0 amp fuse, see the blue item in this photo:
Rebel500 