OBD1 Honda/Acura Wideband Gauge Wiring Instructions
This guide applies to all socketed & tuned OBD1 (1992-1995) Honda/Acura ECUs
There are multiple methods of connecting your 0-5v wideband input to your ECU, we'll be covering both of them here. The first method will involve removing and re-using the original narrowband signal input at D14 on the ECU, this will only allow for a maximum reading of 0.373 volts which will work best for more modern gauges with wider readings such as the AEM X-Series gauge. The second method requires deleting the ELD circuit inside of the ECU and taking over the D10 input on the ECU, this will allow for a true 0-5v reading which may be required for older gauge kits.
Identify your ECU's connectors and pin locations
Focus on connector A and connector D, we won't be using connector B for this install. We'll be using connector A to pull 12v power and ground for the gauge (this is optional but recommended), connector D will be used to send our 0-5v signal to the ECU.
Supplying power/ground to the gauge from the ECU (Optional but recommended)
Start by running power and ground to your gauge and ensure it's functionality.
Connect the +12v wire of your gauge to pin A25 and the ground to pin A26.
The D14 (narrowband signal override) method
The D14 method is very simple as no internal ECU modifications are required. Simply connect your gauge's 0-5v signal wire to the D14 wire going into the ECU making sure to remove the pre-existing wire that was going into D14 as this is the factory narrowband signal wire which we are replacing. If your gauge has a dedicated signal ground connect this to D22.
The D10 (ELD delete) method
The D10 method makes use of the ELD input and requires slight modification of the ECU. Remove the top lid from your ECU and locate resistors labeled R136 and R138, these can be located near the ECU plugs. Cut the leg(s) or desolder both resistors labeled R136 and R138. Once the ECU has been modified accordingly you can wire your 0-5v signal to the D10 pin on your ECU. If your gauge has a dedicated signal ground connect this to D22.
