Friday, March 30, 2018

OBD Bluetooth Scanner DLC power management

Available options for powering the scanner are:

1. (Default) permanent power

  • the scanner stays permanently powered at all times when connected to the DLC port, even if the ignition is switched off, making the scanner drain an average current 4.9 mA. This is not an issue if you drive daily. However if you leave the vehicle sit for a longer period or your battery lifespan is ending, the scanner might contribute to quicker battery drain
    hondash bluetooth scanner permanent power

2. Custom ignition switched power

  • with a little bit of electrician skill you can rewire your DLC connector to a ignition switched power source which will power the scanner only when the key is either in ACC or IGN position, in this example using a mini fuse tap at fuse Nr.27 in under-dash fuse box (cigarette socket power)
    hondash bluetooth scanner ignition switched power
  • if you're not willing to cut the wire, you can also simply disassemble the DLC connector and remove the middle female pin and isolate it, then proceed as described in 3rd option below.

3. External power - OBD1 vehicles without power source in the DLC diagnostic connector

  • some OBD1 cars ('92-'95) don't have any power source in the DLC diagnostic connector (3 pin style connector with only two wires connected to it, middle pin and wire are missing). In this case you have to wire the scanner as described here

  • 1st step:
    prepare the wire on the scanner side
    * If you're using older V1/V2 scanner versions you can use the already pre-soldered wire, which is tucked in the case
  • 2nd step:
    connect the wire to an ignition switched +12V power source, for example using a mini fuse tap to tap the power at fuse Nr. 27 in under-dash fuse box (cigarette socket power), or splice the wire directly to the wire powering the cigarette socket, or use a cigarette socket plug to provide the power.
    hondash bluetooth scanner external power 2
WARNING: Make sure there is no power in the DLC connector, when doing this mod, using two power supplies (DLC connector power source + external wire to another power source) simultaneously may permanently damage the scanner and blow fuses.