| OBD0 to OBD1 conversion This was an ah, interesting, ordeal�yes, ordeal was the correct word. Over all, the process took about 15 hours. Several hours were spent looking over the instructions received from StorminMatt for the process making sure they were correct. They will be listed below. Modifications had to be made to the engine harness and either the dash harness has to be modified or a converter that will allow the OBD1 ECU to be plugged into the 89 dash harness. Engine Harness conversion Note: Removal of the engine harness is recommended due to it making it easier to modify the harness. Wire colors will be listed in this manner red/grn (this means red with a green stripe). Many wires can be pulled out of plugs by pushing in the front (with a small screwdriver, etc) and giving a gentle tug on the back of the wire. 1. The injection resistor must be removed from the circuit. This is because the OBD0 injectors are not compatible with the OBD1 ECU. In order to do this, the yel/blk wire from the green plug on the injection resistor must be pulled. It will be relocated into an open space in a gray 8 wire plug from the OBD1 harness. This OBD1 plug has 8 yel/blk wires leading out from it and has a gray cap on it. Removal of the cap shows that it has an integrated metal clip that connects all the yel/blk wires together. 2. Injector wiring. To use the OBD1 injectors, the injector plugs from the OBD1 harness must be used. Each plug has a different color line (brown, red, light blue and plain yellow�1,2,3,4 injectors respectively) and a yel/blk wire leading from it. The yel/blk wire from each of the injector plugs leads back to the 8 wire plug mentioned in #1. The OBD0 injector plugs must be cut off and the OBD1 injector plugs soldered on. Match the injector colors to each other, as they are the same on both the OBD0 and OBD1 harness. Note: On the OBD0 harness, the wire leading from the injector plug to the injector resistor is red/blk. These wires need not be worried about as they only connects the OBD0 injector plug to the injector resistor. 3. A 4-wire O2 sensor must be added. In order to do this, 3 lines must be added to the harness. One line runs from the O2 sensor plug to the 8 wire plug mentioned in #1, this wire is yel/blk. The second line is a grn/wht line that runs from the O2 sensor plug to any location on the grn/wht wire on the OBD0 harness. The third line is an org/blk line that leads to the ECU. The final wire is the white one. This wire serves the same purpose on both the OBD0 and OBD1 cars. This white wire is the O2 sensor wire itself�on the OBD0 engine harness, it is a single wire and has a rather large plug on it. This plug must be cut off and the white wire for the OBD1 plug soldered on. 4. Distributor rewiring. The lines for the distributor�s 7 wire plug can be pulled on both the engine harnesses. Pull the gray OBD1 7 wire plug for the distributor off the OBD1 engine harness and the replace the 7 wire plug on the OBD0 harness with it. Make sure to match the wires coming from the distributor with the matching colors being put into the 7 wire plug. As for the 2 wire plug, the plug had to be cut off the OBD0 harness and OBD1 plug spliced on. 5. VTEC. One wire must be added to the harness for the VTEC activation wire. It is a grn/yel one-wire plug on the OBD1 harness. This wire must be run into the car and attached to the ECU. 6. VTEC oil pressure sensor. 2 wire plug, one wire black and the other blue/blk. The black wire must be run to a ground and the blue/blk wire runs to the ECU. That�s it for the engine harness conversion. Back Next Home |