ELD pin D10 Wideband Input ECU Board Modification

This article is for OBD1 Civic/Integra USDM style ECU's ONLY (ie: P06,P28, etc). It does not apply for other non-US ECU's.

This ECU board modification will allow your OBD1 ECU to use the ECU pin D10 (ELD) for your wideband signal input. The advantage to using pin D10 instead of the stock O2 sensor pin D14 is that the ELD input is capable of processing a full 0-5 volt signal, while the D14 pin can only process 0-3.73 volts which will limit your air/fuel ratio datalogging ability of the wideband signal.

To use the pin D10 ELD input, simply locate the bank of resistors near the ECU grey plugs labeled R136, R137, and R138. R137 (the middle resistor) should remain intact and unchanged, while R136 and R138 should be removed or cut. Not all circuit boards have a resistor in both locations (as pictured). Just be sure both R136 and R138 are empty or cut and you are good to go.

In the above picture, you can simply cut one "leg" of the resistor in location R136 to break the circuit. Your ECU is then ready to use D10 for your 0-5v wideband input. Be sure to configure your tuning software to use the D10 input now for your wideband instead of the standard D14 O2 sensor input.

Happy Tuning.