Add info on wiring for FT86

can_db/ft86.md

@@ -68,3 +68,27 @@ Channel name | Equation
 ------------ | --------
 Engine oil temperature | C - 40
 Coolant temperature | D - 40
+
+# Connections
+
+Besides the CAN pins in the OBD-II port, there is a CAN bus male port hidden
+behind the car multimedia head unit:
+
+![Hidden CAN port](../images/ft86_hidden_can_connector.jpg)
+
+It's very close to the glovebox, which makes it great for putting your CAN
+reader in the glovebox. Such a placement makes sure it's out of the way and you
+won't accidentally hit it with your leg while on the track, and also allows
+quick access for troubleshooting and experimenting. There's also a second 12V
+port inside the glovebox, which makes it easy to use a 12V-to-USB adapter
+instead of adding a 12V-to-5V converter to your hardware design.
+
+You can use the two middle pins of a
+[Toyota radio harness](https://www.amazon.com/gp/product/B0002BEQJ8)
+to connect to the CAN bus in a reliable way.
+It's recommended to use a ~60–90 cm (2–3') twisted pair cable between that port
+and your CAN reader. I would strongly discourage you from using the screw
+terminals on the MCP2515 board, as if the cable comes loose it can cause a short
+circuit in the CAN bus (ask me how I know), which will throw a MIL at best, and
+who knows what at worst if it happens on the track. Instead, I attached a female
+JST SM connector to the cable.