Login Form

Google Ad

Support / Knowledge

Adding Vtec to a Mini-Me swap (OBD1 Conversion)

Pin It
OBD1 Conversion, Adding Vtec circuit to the Mini-me swap
So you did a Mini-me, you got the ECU stuff all worked out, and now you want your Vtec. Ok, follow along. First off I guess I should show you want I am doing. The goal here is to simply run a new harness from the Vtec components to the ECU. Of course you could go to the junk yard and rob the plugs from an EX and run new wires but for this I am going to fabricate everything from the Vtec solenoid to the ECU.
Step one is to select the right size connectors. These are 1/8" spade connectors (female end) for 14 - 16 gauge wire. The 1/8" spade happens to fit perfectly on the male end of the Vtec solenoid and Vtec pressure switch. See, no junk yard parts needed.


Next I am going to make the ground for the Vtec pressure switch. The ground side of the pressure switch does not need to run back to the ECU. The pressure switch is a simple oil pressure switch that is normally in the open state. When the ECU enables the Vtec solenoid the oil pressure closes this switch completing the circuit. This is so that the ECU can tell that Vtec is physically engaged. Since the ECU is supplying the switch with voltage, only a ground is needed once the switch is closed to complete the circuit.  Also, since this is a simple switched circuit, it does not matter which side of the switch you pick to be the ground.

In the first two pictures I am prepping the ground wire for installation. Pay attention as this is a model you should follow for all wiring. The first step in making a good crimp connection is to always tin the wire with solder. This provides a good surface for the crimp to grab on to. For the pressure circuit small gauge wire can be used, I chose to use 18 gauge wire. Once the connector is in place on the wire I used some heat shrink tub to cover the connectors end. This is needed so the two connectors do not touch and bypass the switch. For the ground I used a screw located directly on the Vtec solenoid itself.

Now its time to run the rest of the harness. I started by locating a spot to run the wires through the firewall. I found the easiest spot is through the boot that most of ECU harness runs through. This can be found directly under the battery in 6th gen EK Civics. Do not confuse it with the other boot located to the left. This comes out directly behind the heater and is VERY hard to access from the ECU's location. After I located the right boot I cut a small slit in it about 1/4" long. Be extremely careful you do not cut any wires while you do this.
The wire I will be using for the Vtec solenoid its self (single black plug) will be 14 gauge wire. This is because the Vtec solenoid requires much more current to operate then a simple pressure switch. 16 gauge wire may also be used for this and is the factory standard.
Using the same technique as above I attached spade connectors to the 18 gauge and 14 gauge wires. I then encased the wires in lomb and ran them through the boot to the inside of the car. Make sure you leave enough wire. Extra is always better then running the entire wire again.
Once the wires are attached to the Vtec components under the hood and ran inside the car its time to start to think about how they will be attached to the ECU. Since this is an OBD2 to OBD1 conversion, a conversion harness was used to attach the obd1 ECU to the stock harness. You could simply hard wire the circuits into the conversion harness. I would suggest using spade connectors or in this case a computer plug so the system can be easily disconnected. I will be using the Yellow side for the pressure switch and the Red for the Vtec solenoid. The small 22 gauge wire running from the Vtec solenoid side will be used for a future Vtec light.

This picture shows the male side of the plug attached to the conversion harness and insulated with heat shrink tubing.

The proper pins used on the OBD1 ECU are as follows.
PIN A4 - Vtec Solenoid
PIN D6 - Pressure Switch

After attaching the female side to the two wires coming from the solenoid and pressure switch, I put the harness in place.

I found it easiest to mount the new ECU with the harness facing up. The obd2 ECU is quite a bit smaller then the obd1 ECU, making mounting a bit tricky. With the gentle persuasion it can be accomplished however.

Any questions about this article can be posted on this sites forum.