Bluetooth OBD that turns on with Ignition Mod

andy_06xi · 11-03-2020, 07:18 AM

I just installed a Eonon GA9465 Android Head Unit in my car. (Seems pretty cool -- though I haven't had it in long enough to fully explore all that it can do).

In any case I wanted to get real-time instruments up through the Torque app via a Bluetooth OBD dongle. I bought one for $14 through Amazon:

https://www.amazon.com/obdator-Bluet...4408582&sr=8-3

One issue with these is that they run off the Battery +12v (pin 16)-- as this is the only 'standard' power in an OBD connector. I want to leave this in all the time, however, and not worry about the battery running down (I've already added the 'standby' load of the Eonon HU -- though a modification to the harness).

BMW OBD connectors however have a +12v at pin 1 that is switched with the ignition. So I thought I'd modify the dongle to take power from than instead. If I screwed it up -- it was only $14.

Using a small screw driver I was able to pop off the plastic top of the device. This exposes the two stacked circuit boards. I was going to remove the top board -- but I couldn't figure out how to do so without breaking it. So I left it on.

I then soldered a small wire from the exposed pin 1 on the bottom circuit board (didn't look like it had any traces connected to it) to pin 16. Actually I soldered to a capacitor on the end of the bottom circuit board that was easier to get to and that ohm'ed out to be connected to the neighboring pin 16. I then pop'ed the plastic top back on.

To prevent shorting the switched and non-switch power -- I then bent pin 16 in the connector until it broke off. I got a pretty clean break near the base of the pin -- but put some JB weld over it just in case.

I then plugged the modified device into my car's OBD port -- Success! No LED's when the ignition is off and the LED's come on once the car is started. No problems connecting to the Torque app and I see the real-time instrumentation.

Of course now this device is 'BMW specialized' -- but I don't really care.

Emilime75 · 11-03-2020, 07:36 AM

Cool. I wonder why BMW chose to have switched power on pin 1. The OBD standard is battery power on 16, so what does switched power on 1 get them?

NoGuru · 11-03-2020, 07:43 AM

Interesting. I might have to try this with my MHD Wifi Dongle.

Emilime75 · 11-03-2020, 10:20 AM

If I was to do this, I think I'd look at disabling power on pin 16. Maybe there's a dedicated fuse for it, or cut the wire and wire a switch in line.

11-03-2020, 07:18 AM	#1
andy_06xi Second Lieutenant 74 Rep 249 Posts Drives: 2006 330xi Join Date: Nov 2006 Location: Boston, MA iTrader: (1)	Bluetooth OBD that turns on with Ignition Mod I just installed a Eonon GA9465 Android Head Unit in my car. (Seems pretty cool -- though I haven't had it in long enough to fully explore all that it can do). In any case I wanted to get real-time instruments up through the Torque app via a Bluetooth OBD dongle. I bought one for $14 through Amazon: https://www.amazon.com/obdator-Bluet...4408582&sr=8-3 One issue with these is that they run off the Battery +12v (pin 16)-- as this is the only 'standard' power in an OBD connector. I want to leave this in all the time, however, and not worry about the battery running down (I've already added the 'standby' load of the Eonon HU -- though a modification to the harness). BMW OBD connectors however have a +12v at pin 1 that is switched with the ignition. So I thought I'd modify the dongle to take power from than instead. If I screwed it up -- it was only $14. Using a small screw driver I was able to pop off the plastic top of the device. This exposes the two stacked circuit boards. I was going to remove the top board -- but I couldn't figure out how to do so without breaking it. So I left it on. I then soldered a small wire from the exposed pin 1 on the bottom circuit board (didn't look like it had any traces connected to it) to pin 16. Actually I soldered to a capacitor on the end of the bottom circuit board that was easier to get to and that ohm'ed out to be connected to the neighboring pin 16. I then pop'ed the plastic top back on. To prevent shorting the switched and non-switch power -- I then bent pin 16 in the connector until it broke off. I got a pretty clean break near the base of the pin -- but put some JB weld over it just in case. I then plugged the modified device into my car's OBD port -- Success! No LED's when the ignition is off and the LED's come on once the car is started. No problems connecting to the Torque app and I see the real-time instrumentation. Of course now this device is 'BMW specialized' -- but I don't really care.
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11-03-2020, 07:36 AM	#2
Emilime75 Colonel 1209 Rep 2,476 Posts Drives: 2010 335i E92 LeMans Blue Join Date: Dec 2017 Location: Merica! iTrader: (1)	Cool. I wonder why BMW chose to have switched power on pin 1. The OBD standard is battery power on 16, so what does switched power on 1 get them?
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11-03-2020, 07:43 AM	#3
NoGuru Major 772 Rep 1,418 Posts Drives: 335is Join Date: Apr 2017 Location: MI iTrader: (0) Garage List 2021 Chevy Silverad ... [0.00] 2002 Jeep Cherokee [0.00] 2014 CTS [0.00] 2011 335is [0.00]	Interesting. I might have to try this with my MHD Wifi Dongle. __________________ 2011 335is DCT BQ Tuning / BMS CAI / VRSF kittyless DP's / Synapse BOV and charge pipe / 7" VRSF Race FMIC / Walbro 535 and 450 on BMP4 / E90 tune / Diff Brace / PR Coils / Relocation Inlets / DAW Stage3+ Turbos / MMP port injection / xHP Stage 3 / FPR and -6 fuel lines
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11-03-2020, 10:20 AM	#4
Emilime75 Colonel 1209 Rep 2,476 Posts Drives: 2010 335i E92 LeMans Blue Join Date: Dec 2017 Location: Merica! iTrader: (1)	If I was to do this, I think I'd look at disabling power on pin 16. Maybe there's a dedicated fuse for it, or cut the wire and wire a switch in line.
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