It is the input from the battery. I would use IGN as on that pin you have power only when the key is in position 1 and 2 (when the radio works). If the BT unit does not need constant powering, connecting to the IGN will stop the BT unit draining the battery when the key is out.

 

THX very much, so what's IGN?

 

From your link for the connector.

IGN	Ignition powered. +12 V with the ignition key is in the ACC or ON position.

 

THX But if I use that for the BT, how to powered the audio 10?

 

You just tap that wire, so it goes to IGN at the same time to BT unit. Don't destroy the connector.

 

THX, so I wrap the wire around from BT to ACC pin and the ground

 

I had one of those units (might still be in the garage). Tapping power from the stereo harness caused a buzz sound. I tapped power from the lighter and ground direct to metal in the area. Buzz reduced to almost nothing.

Sixto
98 E320 wagon 197K miles

 

THX When you said "tapped" you mean say wrap the wire around no solder, so can I always use the lighter for charge or my cigar?

 

https://www.amazon.com/Ginsco-Termi...Terminals-Self-stripping-Insulated-Disconnects/dp/B01CDWC60Y?ref_=fsclp_pl_dp_1

 

Thanks, mrboca, but I hate those things. Thankfully I can R&R a transmission even if I can’t crimp a connector or splice to save my life. In this case, I peel back the insulation from a harness wire, wrap new wire for the accessory then solder and tape.

I wish there was something like this that works in a 3-way junction without cutting the existing wire -

Solder Seal Heat Shrink Butt Connectors

Solder Seal Heat Shrink Butt Connectors A simple one-step connection of wires. Shrink tubing in-line connectors with built in solder. Solder will melt and flow through the inserted stripped wires when heat is applied to ensure a strong, insulated seal. N

www.customdynamics.com

Sixto
98 E320 wagon 198K miles

 

Too much work , especially if the connection is not mission-critical, and in-the-cabin . I actually used the Harbor Freight ones, which makes life even easier (no spade connection, slide the cable in, and then the cable tip of the device, press, and you are done). I used these in various camera installations.
Quick Wire Splice Set, 11/18 And 14/18 Gauge, 50 Pc.

 

thanks so much