piston Posted October 6, 2006 Share Posted October 6, 2006 ive been doing researched on some old threads and found plenty of helpful info. the thing im not sure of is how do i go about wiring the wires that goes into the firewall. i was wondering if i have to use 2 knock sensors or just one? also, how do i got about wiring in an obd1 port to the harness? where do i wire the alternator connector wires to? it doesnt go to the pcm instead leads to the firewall??? im also asuming all the ingition feed that goes to the firewall goes to the ignition feed on the ignition switch itself? the LH-RH o2s sensors also have two wires that goes into the firewall also, are they just positive wires? cant i just use my stock datsun relays to run fuel/fan/lights etc...??? or would i have to wire in my own ralays for the injectors and stuff? im using a 94 caprice harness. any help would be great....thanks in advance... Quote Link to comment Share on other sites More sharing options...
gexgexgexgex Posted October 6, 2006 Share Posted October 6, 2006 Wow your are doing the same thing that i am doing. I have a 240z that im putting in a 94 caprice LT1 motor into it. The caprice uses 2 knock sensors i would keep both, so that you do not have to change the knock thing inside the ECM. You do not need to wire in an OBD port. you only need two wires going to it, the serial data and ground. They come straight out of the ECM. You should find them in a wiring guide. I have not done my alternator yet but what i have heard is, you give it power from the battery and a ignition signal that has a built in resitor like it would be connected to a light. Just search for "lt1 alternator" there are many threads on it the extra harness that you have is more for the body and not to power the ECM, which really only needs about 4 or 5 wires connected to it to run. Just use your datsun relays for fans etc. But i would run new relays to power the ECM and injectors and coil. I know i still have questions but hopefully we can both get our cars runing if we work together. Quote Link to comment Share on other sites More sharing options...
wheelman Posted October 6, 2006 Share Posted October 6, 2006 I used a 95 Caprice motor. Did you guys grab the fuse block from the engine compartment? If not you should have, it contains the fuses and relays you'll want for the fuel pump and fan(s) as well as the fuses for all the engine bay circuits. I basically connected +12, +12 switched and ground to this and that took care of most of the integration with the Datsun harness. The alternator is a different story better left for scary bedtime stories. JK It took me a while to figure it out and totally drained the battery several times because it wasn't being charged. Edit: My Caprice was a 9C1 model with the 140 amp alternator, may be different from what you guys have. The 2 knock sensors actually feed into 1 pin at the PCM, if you remove one you'll need to compensate for the change in resistance so the remaining sensor will work correctly. You also should have grabbed the OBDI test port connector from inside the car. I didn't use it but if you ever want to take the car to a shop to have the codes reset or read you'll need it. I have TunerCat and DataMaster so I used a DB9 RS-232 connector. One thing I learned was it's a bad idea to run the power for the engine bay fuse block through the Datsun Amp meter. I wired it this way at first but way to much current is drawn when the fan kicks on and the wires under the dash got extremely hot. Wheelman Quote Link to comment Share on other sites More sharing options...
gexgexgexgex Posted October 6, 2006 Share Posted October 6, 2006 So how did you do your alternator, so that i do not have to have any scay dreams tonight? Quote Link to comment Share on other sites More sharing options...
wheelman Posted October 7, 2006 Share Posted October 7, 2006 It's been a while so I'll have to trace the wires out and post it. Do you have the 140Amp Alternator? The connections are different for some of the GM alternators. Have you searched the thread here on HybridZ? This subject has been discussed a couple times and I think I described my final solution in one of those threads. Wheelman Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted October 7, 2006 Administrators Share Posted October 7, 2006 So how did you do your alternator, so that i do not have to have any scay dreams tonight? Years ago, when I did my LT1 conversion (95 F-Body), I just excited the field with a wire that was 'hot in run'. I've since done this to a number of other GM alternators without a single failure. IF the caprice is same-same there will be a terminal marked "F". Energize that when the ignition is on and you should be able to sleep tonight HTH Quote Link to comment Share on other sites More sharing options...
80LS1T Posted October 7, 2006 Share Posted October 7, 2006 Years ago, when I did my LT1 conversion (95 F-Body), I just excited the field with a wire that was 'hot in run'. I've since done this to a number of other GM alternators without a single failure. IF the caprice is same-same there will be a terminal marked "F". Energize that when the ignition is on and you should be able to sleep tonight HTH That's how I wired mine too. I haven't had any issues either. Guy Quote Link to comment Share on other sites More sharing options...
piston Posted October 8, 2006 Author Share Posted October 8, 2006 ok, so now i know the knock sensors share one wire to the pcm. now, what wires do i actually use from the ones that goes into the firewall? im assuming the 2 o2 wires that goes to the firewall are constant hot or positive feed wires and the ignition feed also goes to the ignition??? the car itself, 75 280z is fuel injected so i should have the injector relays in. i didnt know the pcm also uses a relay! so if the caprice uses two knock sensors, cant i just get the pcm reprogram since i dont have the pcm yet and planning on to buy a reprogram one anyways? i want to stay away from two knockers if i dont need the other...since im doing my wiring right now and the driver side knock is screwed. i bought the motor with the harness going to the fire wall cut, but i have everything traced and labled ready to loom back up. 40% of the harness has been ripped out already but just still not sure on which wire i need to wire up going to the firewall. thanks for the replies. cant wait to get this thing running at the same time has no time to spare on this project. Quote Link to comment Share on other sites More sharing options...
love-my-V8-280Z Posted October 9, 2006 Share Posted October 9, 2006 Regarding the Alternator. Their are two ways to hook it up. I became confussed and wrecked mine. One) of the contacts on the alternator MUST have the resistance of a small light or it will wreck it. Two) there is a contact that all you need to do is hook 12 volts to it when the key is on and your all set. Don't get them backward! When I write contact I mean hook to one of the hole's in the plug.. Quote Link to comment Share on other sites More sharing options...
wheelman Posted October 9, 2006 Share Posted October 9, 2006 Do you have the underhood fuse box? If you don't you should try to get one from a wrecking yard, it will make the harness integration much easier. The O2 sensor wires should not go into the firewall, neither should any of the other sensors. They all connect directly to the PCM along with several ground and power connections. The PCM will need +12, +12 switched and ground connections. The +12 connections should have fuses inline so if there is a short the PCM won't be fried. The fuel pump, fan(s) and injector power feeds also have fuses. I know this isn't enough information but you really need to get the circuit diagrams for the engine bay circuits. I got mine from the field service manuals at my public library. Photo copied all the pages I needed for about $2.00. Wheelman Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted October 9, 2006 Share Posted October 9, 2006 Piston, Go to this link and I think most of you questions will be answered. http://forums.hybridz.org/showthread.php?t=105112&highlight=lt1 Danno74Z Quote Link to comment Share on other sites More sharing options...
piston Posted October 9, 2006 Author Share Posted October 9, 2006 yeah, i was looking at that site for the longest time but not sure on what they mean by pug c100 and stuff. i thought it was by colors? that kinda confused me for a bit. the two pink wires from the o2 sensors leads somewhere if not firewall but its cut off along with the harness where it leads to the firewall. i dont have a fuse box since i only bought the motor and harness. alot of the wires i did trace leading to be cut off along with the harness like i said, leading to the firwall. ill go home in a bit let you guys know which wires am talking about since i have the labled already. thers gotta be at least 4 or 5 ignition feeds and same goes to sensor wires. im sure the harness is very similar to all other lt1 harness. its from a 94 lt1 lc1 cop car if that might make any difference. Quote Link to comment Share on other sites More sharing options...
wheelman Posted October 9, 2006 Share Posted October 9, 2006 Sounds like most, if not all the wires you're thinking go to the firewall really terminated at the underhood fuse box. I don't remember seeing 2 pink wires going to each of the O2 sensors, do you really mean there is 1 pink going to each? The pink (with no stripes) wires in my harness were all power wires for the sensors and injectors. There is also an orange wire(s) that connects to the oil pressure sender/switch, PCM and fuel pump relay that provides power to the fuel pump. It also terminates at the underhood fuse box. This may sound confusing but one pink wire goes from the fuse box to all the injectors. The other wire from each injector goes to the PCM. The PCM uses this wire to provide a connection to ground so current can flow from the battery through the pink wire to the ground through the PCM. As far as I know the only real difference between the cop cars and the civillian cars were the green silicon cooling hoses, extra engine oil and tranny coolers and double fans. The cops cars had the 140Amp alternator as mentioned before but the civillian cars might have also had it. Hope this helps. wheelman Quote Link to comment Share on other sites More sharing options...
piston Posted October 9, 2006 Author Share Posted October 9, 2006 yeah, i traced the wire and one leads to lho2 and one to rho2. i can double check later. i also had that in mind that all the wires i think goes to the firwall actuall goes to the relay box but since they cut it off so short, it look slike it goes along with the harness into the firewall. i took out the oil pressure sender switch since ill be using an aftermarket oil gauge. i have the injector wire labled already. so this is the wire to the injector relay correct. then the ignition feeds goes to the ignition feed or hot! sorry to ask the same question over and over but which wire do i actually only need to wire up. someone told me that i only need just 5 wires running to the firewall to be wired up to make the lt1 run, which wires are these to be exact? Quote Link to comment Share on other sites More sharing options...
wheelman Posted October 9, 2006 Share Posted October 9, 2006 Sounds to me like you are going to have to rebuild a lot more of your harness than you planned on. If you had that under fuse box and didn't remove any of the circuits then it would be as simple as connecting +12, +12 switched and ground to the appropriate connectors and you'd be good to go. obviously you'd also need to connect the starter and alternator but those are separate. Based on what you've posted you are going to need to build curcuits that provide power and fuses for the sensors, injectors, fuel pump and fan(s) and relays for the fuel pump and fan(s). There are no relays for the injectors. I don't remember how the ignition connected to the PCM but you might have to rebuild part of that as well. Seeing as you are missing a large portion of the harness that I had available I really can't answer your question completely. Sorry man. Would you be able to get a complete engine bay harness and PCM from a local JY? This would make your life much easier. Am I remembering correctly when I think you don't have a PCM yet? What tranny are you going to use? Are you removing the emissions equipment? What about the power steering and AC? Wheelman Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted October 9, 2006 Share Posted October 9, 2006 Yes you are correct about the 5 min. wire hookup to the LT1 engine. If all your plugs have been cut off from you LT1 harness which I think you are saying I would stop and either buy a harness that has been made for a stand alone LT1 or buy a used harness and modify it. You need to know what C100, C105, C210, C220, and C230 plugs are because you will be tapping into these plugs with some of the Datsun wiring. http://shbox.com/1/harness.htm Look at this picture above. Does your harness have all these connections? You need them all to run the engine. Some can be deleted but let's not even go there until you tell us what you have. Danno74z Quote Link to comment Share on other sites More sharing options...
wheelman Posted October 9, 2006 Share Posted October 9, 2006 Danno, If his engine and harness (or whats left of it) came from a Caprice it won't have those connectors you mentioned, it will have an underhood fusebox that replaces those circuits. I agree with you, he should buy either a complete aftermarket or stock harness and then go from there. Wheelman Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted October 9, 2006 Share Posted October 9, 2006 Wheelman, There is that much of difference between the Camaro LT1 harness and the Caprice harness? I had no idea! Piston, Since my Z car is a 74 and not a 78 FI model I need at a minimum of 4 more relays to run my Camaro LT1 engine. I purchased a harness from this fellow to do this. http://cgi.ebay.com/ebaymotors/JEEP-CJ-SJ-WIRING-HARNESS-with-LT1_W0QQcmdZViewItemQQcategoryZ80739QQhashZitem230019451216QQihZ013QQitemZ230019451216QQtcZphoto "This is just an example of what he does". This is to run everything on a jeep with an LT1 engine. You don't need such a complete wiring kit. He has a standalone harness with the minimum of wires for $99 and the quality is great. Danno74Z Quote Link to comment Share on other sites More sharing options...
piston Posted October 10, 2006 Author Share Posted October 10, 2006 well, according to the harness i have, it is missing alot of things but i dont see why i would need a new one to rewire it when i have it all traced out and labled already. the only thing missing is the connectors if it even has one on the caprice. i was thinking about just wiring in new relays for fans, pcm, fuel pump etc. cant i just use my stock relay for my datsun fuel pump? only 5 wires needed so why do i actually need a new harness? it has all the connectors for all the sensors on the motor itself. like i said, just missing the fuse box. im sure this wire is very usable, im just not too sure on which wire needs to be hook up and which ones i dont need. this is what i have in mind on doing my wiring. http://cgi.ebay.com/ebaymotors/Custom-Made-4U-Stand-Alone-LT1-GM-Engine-wiring-harness_W0QQcmdZViewItemQQcategoryZ34202QQihZ002QQitemZ4634398351QQrdZ1QQsspagenameZWD1V im not running any emissons or any ac or power steering. just plain motor. im planning on using the stock relays and stuff for my chasis lights. i was thinking any wires not running from the pcm, i dont need since the pcm does not control my lights etc. isnt that how its suppose to be? the pcm im thinking has nothing to do with my brake light or light switches or signal etc. i have only about no more then 10 wires on the cut harness but i have them already traced. im sure i dont need to spend another 100 buying one with just a couple extra wires. im running this engine as basic as possible. as long as it runs and starts normally. nothing special. so now the question is....do i really need to invest on another harness with those cplugs? doesnt make since to buy a new harness. i have everyone of those connectors in the pic above danno74z posted except for the c connectors. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted October 10, 2006 Share Posted October 10, 2006 Piston, What you want to do with your existing harness can be done (as in your link above). You said you have 10 cut wires, ok do you know what those ten cut wire control? If you do great. Wire up some relays for the fan, fuel pump, starter and your done - maybe if you know what you're doing. You can also go this route. Take you're existing harness off the engine and send it to one of these shops and they will build you a harness WITH the relays in place and you will only have to hook (4-5 wires) it into the chassis harness. Bingo Done. Good luck. http://www.lt1350.com/ $325.00 http://www.currentperformance.com/eng_mgt.html#Mod $375 Don't forget you will have to delete all the emissions stuff out of the computer and delete VATS or get a VATS delete module or she won't run. Danno74Z Quote Link to comment Share on other sites More sharing options...
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