This how-to is to show how you install an indicator LED to notify you when MIVEC is engaged on a 4G69. Things you need:
- 12v automotive relay that is on when no power is applied to it, and off when power is applied.
- A few different colors of wire. I used 16g, because I had it lying around, but 20-22g wire will be adequate.
- Wire splices, or soldering equipment
1. Disconnect battery. Always a good idea when doing electrical work.
2. Remove glovebox and the plastic trim piece that covers the ECU plugs.
3. Locate the oil control valve wire. It's light pink with a black stripe and located at pin 95.
4. Splice a wire in with that wire. This will become the control wire for the relay. I used a plastic quick-splice, which works fine. You could solder it if you prefer. Route the control wire to wherever you plan to place the relay. I put it in the driver's footwell up near the OBDII port. There's a perfect flat metal spot there to stick it with some double-sided foam tape.
5. If you plan to place your LEDs where I did, do that now. Remove the gauge cluster from the car, remove the clear and black trim pieces, and install the light. Run the positive wire from your LED assembly to the relay location, then ground the negative wire.
6. Splice into a switched power source. The cigarette lighter is an easy one to use. Run that wire to the relay location.
7. Finally, run a ground wire to the relay location.
8. At this point, you should have 4 wires at the relay location waiting to be hooked up. Here's how they go on the relay I used.
From left to right:
1 - unused, on this relay that would be the port for if I wanted power when the relay had power
2 - ACC power source
3 - positive wire to LED - port on the relay that gets power when there's no power to the relay
4 - Ground
5 - Wire to oil control valve wire. This activates/deactivates the relay.
9. Strip and install the wires at each of the correct locations. Now, before reassembling your interior, test it out. Reconnect your battery, start the car and let it idle for 10 minutes so the ECU can relearn and to let the engine warm up. Now rev your car (in neutral, please.) The light should go on past 3500 rpm, and off when it drops back down.
10. Reassemble your interior and enjoy.
One note. If you put the light in the cluster, like I did, don't make the mistake I did. Put plugs on the two LED wires, so if you ever have to pull the cluster again, you don't have to cut the wires.
