joey j Posted April 4, 2015 Share Posted April 4, 2015 (edited) I've been a long time lurker of Hybrid Z and now that i am looking into doing an RB25DET swap into my 280z it's time to introduce my self. I have a 77' 280z with some minor cosmetic modifications (flares, low, wide wheels.. you know the basics. Now it's time to work on the motor, but i need some help. A lot of it! On to the noob question... If the OEM ECU is replaced with the RB25DET ECU how does the wiring for the headlights, tailights ect. work? Is the wiring harness for all that separate from the engine harness? This picture below is telling me otherwise. I am relatively mechanically savy so i will be attempting to do all the wiring harness using the great info from this forum's members. I'm trying to gather as much information as i can before jumping into this. Any help is greatly appreciated! Edited April 4, 2015 by joey j Quote Link to comment Share on other sites More sharing options...
helghast7 Posted April 5, 2015 Share Posted April 5, 2015 After doing this swap myself I'll say this; you pretty much want to wire up the engine as if you want to run it off an engine stand. Personally I bought a wiring specialties harness, but even if you follow Chris' guide up further, its pretty much what your doing. These cars are too old and simple to have an integrated harness like a 240sx would. Quote Link to comment Share on other sites More sharing options...
joey j Posted April 5, 2015 Author Share Posted April 5, 2015 After doing this swap myself I'll say this; you pretty much want to wire up the engine as if you want to run it off an engine stand. Personally I bought a wiring specialties harness, but even if you follow Chris' guide up further, its pretty much what your doing. These cars are too old and simple to have an integrated harness like a 240sx would. How do you like the pre-made harness? I assume those are literally plug and play. I was comtemplating going that route to keep things a little cleaner. The car is going to be a show/weekend car so I need to make it street legal. Head and tail lights are a must for me. Quote Link to comment Share on other sites More sharing options...
helghast7 Posted April 6, 2015 Share Posted April 6, 2015 Just installed it this weekend, I love it! No kidding what so ever, once i connected all the sensors on the engine it was literally 4 wires to connect and she's running without a hitch. Like I said its nothing like a 240sx, whether you wire it yourself or you buy the harness, its not designed to replace the body harness like in the SX, you wire it as if you wanted the engine to run outside of the car, you keep all the factory wiring for the car. You simply give the engine constant power, ignition switched power, ground, starter circuit and fuel and thats it. Headlights are from the car, tails, turn signal, if you wire yourself so is the starting and charging wiring are all from the car. Quote Link to comment Share on other sites More sharing options...
joey j Posted April 6, 2015 Author Share Posted April 6, 2015 Just installed it this weekend, I love it! No kidding what so ever, once i connected all the sensors on the engine it was literally 4 wires to connect and she's running without a hitch. Like I said its nothing like a 240sx, whether you wire it yourself or you buy the harness, its not designed to replace the body harness like in the SX, you wire it as if you wanted the engine to run outside of the car, you keep all the factory wiring for the car. You simply give the engine constant power, ignition switched power, ground, starter circuit and fuel and thats it. Headlights are from the car, tails, turn signal, if you wire yourself so is the starting and charging wiring are all from the car. Thanks for the info buddy, it greatly helps. I'll most likely go that same route and try and find a shop to wire up lights and stuff. Quote Link to comment Share on other sites More sharing options...
Vandergriff84 Posted April 8, 2015 Share Posted April 8, 2015 I used an old harness from McKinney motorsports and like helghast7 said it could run the motor on a stand with a battery. There is just a couple of wires to connect and you are good to go. I read through Chris' instructions and I would have done it my self if the package deal I got on mounts and drive shaft hadn't already come with the harness. You shouldn't have to do any thing to keep your lights working just make sure that you don't cut any of those wires out when you clean up the engine bay. I took everything out of mine except the head lights, wipers, the wires for the starter and alternator. Your tail lights are on a separate terminal so there is nothing to change there. Quote Link to comment Share on other sites More sharing options...
joey j Posted April 8, 2015 Author Share Posted April 8, 2015 I used an old harness from McKinney motorsports and like helghast7 said it could run the motor on a stand with a battery. There is just a couple of wires to connect and you are good to go. I read through Chris' instructions and I would have done it my self if the package deal I got on mounts and drive shaft hadn't already come with the harness. You shouldn't have to do any thing to keep your lights working just make sure that you don't cut any of those wires out when you clean up the engine bay. I took everything out of mine except the head lights, wipers, the wires for the starter and alternator. Your tail lights are on a separate terminal so there is nothing to change there. I thought the lights were all connected to the ECU together with the engine harness. Is that not correct? Quote Link to comment Share on other sites More sharing options...
Vandergriff84 Posted April 9, 2015 Share Posted April 9, 2015 Not typically. The ECU, especially on older cars pretty much controls the engine only. The lights on my 74 are only controlled by the switches and turn signal relays. I don't think they changed much going into the 280z other than they might have added relays for the head lights but I am not sure on that. Since mine was a carbureted to begin with I started out buy locating the things I needed to keep ie(head lights and wiper motor) and then I just cut out the rest of the wires since the engine harness has everything needed for the motor to run. Quote Link to comment Share on other sites More sharing options...
helghast7 Posted April 9, 2015 Share Posted April 9, 2015 My 78's engine harness was almost completely separate from the body harness, minus the wires for the coil and distributor i believe. Everything engine related is on another harness that comes into the engine bay from the drivers side. The computer even gets its own power source and relay outside of the fusebox. Quote Link to comment Share on other sites More sharing options...
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