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Wiring the Innovate LM-1 to OBD1 ECU

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Adding the Innovate LM-1 wideband controller to the Honda OBD1 ECU.

 

With this mod you should be able to use the wide band o2 sensor in place of the stock narrow band sensor with use of the LM-1 as a mediator.

I am doing this on an OBD2b to OBD1 conversion harness though the same applies to the OBD1 stock Honda harness. First locate the primary o2 signal (also called the input wire) and ground wires. The signal wire is pin D14 and the sensor ground is pin D22 on the OBD1 ECU. If you need help you can refer to the ECU pin out diagram on this site.

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Cut both the signal and ground wires but leave enough on each side to strip and spice them back together. Once they are stripped, splice them back together but include your new LM-1 signal and ground wires. You may splice in the LM-1 signal wire only and leave the stock (now unused) narrow band signal wire disconnected, however, I am going to also splice this back in, in case I ever want to install a narrow band sensor again in the stock location. Note: You can ONLY leave the stock o2 signal wire disconnected from the ECU. The ground must be re attached to the ECU as it functions as a common ground for many other sensors.

Personally I like to make everything removable so instead of running the new wires directly to the LM-1 unit, I added an interlocking connector so that I can unplug the LM-1 signal wires from the ECU. RadioShack part number 274-222.

To connect the new signal wires to the LM-1 unit you are going to need a Stereo 3.5mm (1/4”) Phone Plug. RadioShack part number 274-284. This HAS to be a stereo plug because both analog channels 1 and 2 + the ground use the same phone jack on the LM-1. Analog channel 1 uses the tip of the phone plug, followed by channel 2 in the center, and ground at the base. In this article I am only using analog channel 1, so there are only 2 wires connected to the stereo plug. Analog channel 1 and the ground wire. If you wanted to use the LM-1 to emulate a narrow band AND wide band analog outputs you would simply hook a third wire to the Analog 2 output in the stereo phone plug. An example of when you may need both channels is if you were data logging with the ECU (as used in this article) and also wanted to add a separate stand alone A/F display on the dash.

Once this wiring is done you are ready to program the analog outputs of the LM-1 to suite your needs.