Bartman Posted October 11, 2006 Share Posted October 11, 2006 You can definitely wire everything yourself, but you need the proper wiring diagrams (along with alot of patience). If you can get a copy of the Factory Service Manual covering the donor car, it will be a big help. I did pretty much what you are doing (with some help from the previous owner), and it just takes some time and investigation. On my car the fans and the fuel pump are activated by a ground wire coming from the PCM. You just need to figure out which wires these are and use them to activate relays (it's relatively easy to wire a relay so that it sends out power based on a negative signal). I used a Painless fuse block for my constant hot and ignition hot PCM wires, but you could conceivably use wires from your Datsun (if you're really hurtng for cash). http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRF%2D70103&N=700+4294843320+115&autoview=sku Good Luck. Quote Link to comment Share on other sites More sharing options...
wheelman Posted October 11, 2006 Share Posted October 11, 2006 As Bart and Danno have stated it's possible to use the harness you already have, I made the statement about buying a new complete harness based on your repeated statement about only connecting 5 wires and everything works. With your harness as hacked up as you make it sound this is not going to happen. It should be possible to use the Datsun fuel pump relay, you just need to figure out which PCM connector controls that relay, if you want the PCM to energize the pump before the engine fires, and connect it up, you'll also want to use an oil pressure switch that also closes the same relay to keep the motor running once the PCM opens it's circuit. The PCM will only run the pump for a couple seconds when the ignition is first turned on, this primes the fuel system before cranking. Edit: I suppose you could also just have the ignition switch close the fuel pump relay and the pump run while the switch is on. The one drawback to this is if a fuel line is cut and the engine dies the pump will continue to run dumping fuel everywhere causing a major fire hazard. An oil pressure switch prevents this by opening the relay when the oil pressure drops shutting off the pump. Hope this helps. Wheelman Quote Link to comment Share on other sites More sharing options...
piston Posted October 11, 2006 Author Share Posted October 11, 2006 here are the wires i have thas been cut and only wires that actually there... 2 brown= alternator 2 pink, 2 orange= ignition feed 1 pink= lh o2 1 pink= rh o2 1 pink= fuel injectors 1 green w/ white tracer= vss output 1 brown w/ white tracer= check engine 1 purple= brake signal 1 blue= knock sensor 1 pink= evap solenoid thats it. nothing more. im using 12v 30amp relays and a 10 pin painless fuse block and a constant hot 5 terminal positive block. if anyone can direct me on which wires goes where and which needs relays, it will be great!!! most of them are pin, im thinking goes to relays or positive but dont want to hook up a relay where i dont need. any help would be good. thanks Quote Link to comment Share on other sites More sharing options...
Bartman Posted October 11, 2006 Share Posted October 11, 2006 here are the wires i have thas been cut and only wires that actually there... 2 brown= alternator 2 pink, 2 orange= ignition feed 1 pink= lh o2 1 pink= rh o2 1 pink= fuel injectors 1 green w/ white tracer= vss output 1 brown w/ white tracer= check engine 1 purple= brake signal 1 blue= knock sensor 1 pink= evap solenoid thats it. nothing more. im using 12v 30amp relays and a 10 pin painless fuse block and a constant hot 5 terminal positive block. if anyone can direct me on which wires goes where and which needs relays, it will be great!!! most of them are pin, im thinking goes to relays or positive but dont want to hook up a relay where i dont need. any help would be good. thanks Okay, I'll give it a shot. I don't think anything you listed needs a relay. The pink wires sound like they need 12V ignition positive from your new fuse block. The check engine wire needs to go with an ignition hot to a light you probably want somewhere on your dash (it sends ground to activate the light). The knock sensor wire goes between the knock sensor on your block and the PCM, I think the VSS output goes from a connector that connects to your transmission to the PCM, and I don't think you need to use the evap solenoid. That's not everything you listed, but it's a start. I still strongly recommend getting the FSM or signing up for alldata. Quote Link to comment Share on other sites More sharing options...
piston Posted October 11, 2006 Author Share Posted October 11, 2006 thats what i thought? so which wires do lead to a relay? all the wires to the pcm goes back and forth and these are the only wires leading out and cut. so where does my relays go??? these are the only wires that leads out and only wires i can use to wire it up. theres no extra wires anywhere! i have an idea where the basic wires go but not too sure. Quote Link to comment Share on other sites More sharing options...
Bartman Posted October 11, 2006 Share Posted October 11, 2006 thats what i thought? so which wires do lead to a relay? all the wires to the pcm goes back and forth and these are the only wires leading out and cut. so where does my relays go??? these are the only wires that leads out and only wires i can use to wire it up. theres no extra wires anywhere! i have an idea where the basic wires go but not too sure.Off hand the only relays I can think of (without AC) are the ones for the fans (primary and secondary) and the fuel pump. You need the wiring diagram and figure out which PCM pins are supposed to control what(i.e. - A11 for cooling fan). You can then trace the wire from this PCM location and find out where the other end of the wire is located at. This link may help: http://www.thirdgen.org/techboard/ltx-lsx/176800-lt1-wiring-dummies.html Quote Link to comment Share on other sites More sharing options...
piston Posted October 11, 2006 Author Share Posted October 11, 2006 after looking at it, i did have the c105 and c100 connectors but they do not lead to the pcm at all or any of the connectors on the engine. the only ones i didnt have is c210, c220, and c230. every connector on the engine leads to the pcm. i took out everything i didnt need according to tim240z post a while back. according to his delete post on what to keep on the red-black-white-blue connectors. the wires i list are the only options i have left. no others. Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted October 14, 2006 Share Posted October 14, 2006 Piston, If you interested I have several photos that may help. I installed the PCM under my dash. Once you have the correct information its easy.. Quote Link to comment Share on other sites More sharing options...
piston Posted October 15, 2006 Author Share Posted October 15, 2006 the relays in the pics from above on the right side in front of the pcm, those are stock relays correct? looks like you just wired it into the stock relays! i wish i can wired my pcm the same way but i cant since its mounted in the front because its a caprice harness. in order for me to do this, i have to cut all the wires and extend them to make it mount in the passenger side, too much work. im guessing this picture shows the c connectors wired into the stock wiring under the passenger? my main concern is how to wire up the wires i have listed. thats the main thing since i dont have any other wires anywhere. the c connectors...do they run to the pcm to because i deleted everything not neccesary and have no wires left except the ones listed. i though for a bit that the c connectors probably goes somehwere besides the pcm corect? Quote Link to comment Share on other sites More sharing options...
piston Posted October 18, 2006 Author Share Posted October 18, 2006 is there anyone else out there that might know how to hook these wires up correctly??? Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted October 18, 2006 Share Posted October 18, 2006 Piston, With out reading all the last postings, I don't think you are going to get someone just telling you to plug wire “a” into spot” b”. You need to know the details of each wire. I have lots of data that might help, start with the helms manual on your car, it will show you every pin on the PCM and what the wire does. You need a relay when you want to run a something that takes a lot of current. Like your headlights or fuel pump. The PCM is a switch and it cant take much current so you have it close a small current relay that will than close and allow a lot of current to flow to the head lights or fuel pump etc... Do you know how to read a wiring diagram? I took a 280Z diagram and have change it to match my 280Z with a 95 LT1.. It would help you a lot.. Also Its not a couple hour job for a beginner to figure all this out.. I have many, many hours getting it right and doing a lot of tweaking to suit my fussiness. Quote Link to comment Share on other sites More sharing options...
piston Posted October 19, 2006 Author Share Posted October 19, 2006 the wires listed are labeled already!!! i was just wondering if anyone knows if any of these uses a relay like injector wise. and which pcm wire uses a relay since the pcm needs a relay wired in is what i was told. i dont have anything on the harness that needs to connect to the datsun harness for lights etc.... yes i know how to read a wiring diagram...the diagram im reading is from a caprice lt1 manual. the pins on the pcm, i know waht it does from tims delete post a while back listing every pin in each connector. the only wires that leads to the pcm are the 2 orange ignition feed,2 pink ignition feed,vss, brake signal and check engine wire. i know where these goes already. just curiouse if the injectors really takes a relay and which pcm wire does the inline relay go to! everything on the chasis is going to be wired with the stock datsun or stand alone relay like fan wise and fuel pump etc... thers not much left to do as you can see from the wire options i have. im just asking to see if someone else might know and throw in their opinions on hooking the wires up to see if its what i had in mind. thanks.. Quote Link to comment Share on other sites More sharing options...
wheelman Posted October 19, 2006 Share Posted October 19, 2006 The injectors do not require a relay but you want to put a fuse on the power feed ciruit to protect the PCM in case of a short. The ONLY circuits you will need relays on are the fuel pump and fan(s) assuming you use the PCM to control them. This is why I suggested you get the underhood fuse box or a new harness from a Caprice that includes it. All the fuses and relays are there with the correct connections. Wheelman Quote Link to comment Share on other sites More sharing options...
azguy Posted October 20, 2006 Share Posted October 20, 2006 Just a note on the knock sensors wiring. WIRE THEM BOTH UP AND SPICE INTO ONE WIRE BACK TO PCM. I ordered a Painless wiring harness for my 94 LT1 install. The harness only came with one knock sensor connector. I had a check engine light on for some time before I figured out why. It kept throwing a code for the knock sensor circuit. I ran freescan which showed me that it was only running default advance of the timing and no more because of the fault code. Something like 17 but depending on rpm. I checked Alldata and found that the knock sensor circuit must have a (I believe) 5 ohm resistance in the circuit. 2.5 ohm from each knock sensor. If the pcm senses below 3 ohm or above 5 ohm it sets a knock sensor code and defaults to programmed timing advance. NO BUENO! So wire them both up to the same wire or wire one up and splice in a 2.5 ohm resistor in the circuit. -- I am guessing on the resistance values, I think they are right but you should double check. It's been a while. Quote Link to comment Share on other sites More sharing options...
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