Finally figured out the twin relays on the RB20.

[chrism]

Finally figured out the twin relays on the RB20. When I applied power to the white and purple wire going to the ignition coil relay, the car would spark but the injectors would not work. I looked at the grounding wires on the ECU and noticed that both of these relays get a ground signal from the same pin #16 on the ECU. Also, when the ignition coil relay is connected to power, it drains the battery while the car is not running. When I opened the wire harness past the ECCU connector for about 1 ft, I found the purple and white wire and the black and white wire were tied together. One of them is used to supply 12v from battery to the relay and the other is used to energize the coil in the relay. I cut the black and white wire loose and tied that to power when on seperate from 12v battery.

Then when I put the relay back in, I noticed that the fuel pump and ECU powered up with no key in the ignition. Same as before. That is what was draining the battery. The only thing that I can think of is that the ground wire that ties both relays together was somehow being pulled low and turning on the ECCS relay. If you look at the schematic, you will see that both the 12v supply and coil input voltage are tied together for the ECCS relay

Not sure why it doesn't cause issues with the skyline and I don’t know what is going on inside the ECCU. So, I cut the orange wire from the Ignition coil relay and ran that to chassis ground. Now the ECCU only comes on when the key is turned on and the Ignition coil relay works using chassis ground instead of getting ground from the ECCU. The battery does not get drained and the car starts fine. I’m not having problems anymore.

In summary, on the Ignition coil relay, cut the black and white wire loose from the harness (ignition coil relay) and tie it to power when on. Then cut the orange wire from the Ignition coil relay and ground pin #16 and run that to chassis ground being careful not the disconnect the orange wire between the ECCU and pin#16. That should solve the battery draining issue, provide plenty of power to the Ignition coils, and allow the injectors to open and close properly. If you think you’re having this problem then try a simple test. When the key is out of the ignition, Is the light to the ECU still on. You may not hear the fuel pump turn on because pressure has built up in the line.

[Z U L8R]

i just take out the other relay....

 

with both relays the ecu wouldn't turn off. when i took one out, everything works perfectly