OBD0 DPFI to OBD1 Conversion Harness Installation Instructions
If there are certain sensors that your engine or ECU does not require, just tape off that wire and leave it unhooked. You will need to have a STOCK wire harness where it plugs into the ECU. No added VTEC wires, etc. - STOCK. You will connect all of the new wires later. So after you have a completely stock harness, plug the ECU jumper into the stock ECU harness plugs and lets go:
- OBD0 DPFI to OBD1 ECU jumper harness.
- OBD1 or OBD2 distributor that fits onto your engine.
- OBD1 ECU
- OBD1 or OBD2 fuel injectors and injector clips. (optional - you can use stock OBD0 MPFI injectors with a stock OBD0 MPFI injector resistor box).
- 4-wire O2 sensor (optional - if you are using a chipped/programmable OBD1 ECU with O2 sensor disabled you do not need to wire in a 4-wire O2 sensor)
On the 12-pin subharness:
1. Connect the BROWN wire to one of the black wires on the 4-wire O2 sensor (O2 heater control).
2. Connect the PURPLE wire to the green wire on the 4-wire O2 sensor (O2 ground).
3. Connect the YELLOW wire to one of the black wires on the 4-wire O2 sensor (O2 12v switch).
4. Connect the GREY wire to the white wire on the 4-wire O2 sensor (O2 signal).
Due to the number of different O2 sensor wire colors with aftermarket O2 sensors, these may vary, and you may need to try moving these. The colors listed in steps 1-4 should match the OEM Honda/Acura OBD1 civic and integra O2 sensors.
5. Connect the BLACK wire to the VTEC solenoid.
6. Connect the LIGHT BLUE wire to the VTEC pressure switch. The VTEC pressure switch is located below the VTEC solenoid. Connect the LIGHT BLUE wire on the conversion harness to the blue wire on the VTEC pressure switch connector. The other wire on the VTEC pressure switch connector should be connected to ground (recommended to connect to ground on thermostat housing).
7. Connect the WHITE wire to the knock sensor located on the back of the engine block. If your engine does not have a knock sensor, simply tape off this wire and leave it unhooked.
8. If you are using a GSR or H22 intake manifold and ECU with IAB control (ie: P72, P13), you can connect the RED wire to the pink/blue IAB wire of the IAB solenoid connector. The black/yellow wire from the IAB solenoid connector needs to be wired to a switched 12v power source. If you are not using IAB's, simply tape off this wire and leave it unhooked.
9. Connect the GREEN wire on the subharness to the blue wire with a green stripe on the OBD1 distributor (CKPP)
10. Connect the YELLOW (PINK on harnesses after 11/2017) wire on the subharness to the blue wire with a yellow stripe on the OBD1 distributor (CKPM)
11. Cut the 2 stock fuel injector plugs off of your DPFI engine harness. There will be two yellow wires with black stripes, one red wire, and one yellow wire.
12. Wire the (4) new MPFI fuel injector clips to match the colors as follows:
- #1 Injector brown wire connects to the orange wire off the subharness.
- #2 Injector red wire connects to the red wire that was cut in step 11 above.
- #3 Injector blue wire connects to the blue wire off the subharness.
- #4 Injector yellow wire connect to the yellow wire that was cut in step 11 above.
13. If running OBD1 or OBD2 (high impedance) fuel injectors, take the remaining two yellow wires with black stripes that were cut in step 3 above on the OBD0 engine harness and ALL four of the yellow wires with black stripes from the new injector clips and solder them all together. Cover the solder connection with heat shrink.
14. If running OBD0 (low impedance) fuel injectors, you will need a resistor box and pigtail or cut the connector off to expose the wires. Take the remaining two yellow wires with black stripes that were cut in step 11 above on the OBD0 engine harness and connect them both to the one red wire on the resistor box. The remaining 4 yellow with black stripe wires (or may be solid black) from the resistor box need to be wired individually to the yellow with black stripe wires on the new injector clips. Do this for all four fuel injectors.
15. The outer two wires of the Throttle Position Sensor (TPS) need to be switched at the connector. Switch the two outer wires with each other (green wire with a white stripe, and the green wire with the yellow stripe).
You will need to re-pin the OBD1 or OBD2 distributor to match the 88-91 OBD0 distributor plug (or use one of our distributor adapters). This step is fairly easy, just match all the colors up. There should be 2 white wires that are on the OBD0 distributor plug and only one white wire on the OBD1 or OBD2 distributor plug, plus an extra yellow/green wire. The larger of the two white wires on the OBD0 side needs to go to the yellow/green wire on the OBD1/OBD2 distributor. The smaller white wire on the OBD0 side needs to go to the white wire on the OBD1 side. We recommend that you solder/heat shrink the connections if you have cut/spiced the connections.
Check Engine Light Function:
OBD0 vehicles use an LED on the ECU that flashes check engine light codes, while OBD1 vehicles require you to jumper the service check connector to flash check engine light codes on the dash. This harness is designed for you to use your factory 2-pin ignition timing adjuster connector. Jumping this connector will now allow your factory dash check engine symbol to flash check engine codes just like on OBD1 vehicles. This connector is located near the driver's side shock tower on 1988-1989 chassis', and located in the passenger side kick panel area on the 1990-1991 chassis'.