Need final wiring help for LS1/LS2 conversion

[RebekahsZ]

I am in the garage today trying to finish the wiring. I've only had one fire today-we'll see how much of the harness/ECU I've fried-glad I installed that quick disconnect on the ground wire. I let my positive lead to the starter ground out to the engine block while I was searching for an accessory "on" wire under the hood. Didn't find the "acc on" wire cause I almost crapped my pants when smoke started coming out of my main connector to the ECu. The connector is lightly burned and may still function-we'll see.

 

I have the battery cables wired from the trunk to the firewall with bulkhead connectors. I have my fuel and fan relays mounted and I understand how to wire them. Problem is the few wires that are marked from waitformeperformance (who is at a car show until next week), but I don't know what needs to be run thru the fuse block and what can be wired directly. I can turn over the motor with the ignition key. Also, what wires can be neglected (backup lights, etc).

 

If you can help me, especially mnoel and cable, but anyone else please chime in-I want to finish this wiring this week and my wife is all over me to do stuff for her as soon as I can.

 

Call to my cell 256-366-4685 if you can help me while I call out a few wires and ask advice on each one (probably less than 10 wires).

 

Thanks,

Keith

Edited December 29, 2011 by RebekahsZ

[RebekahsZ]

I got one PM-reply on my request for wiring help. I'll try being more specific. I have a '72 240z with LS2/T56 from a 2006 GTO. I had my wiring harness and PCM re-worked by waitformeperformance, but I can't get them to answer my questions.

 

1) Yellow "Accessory Voltage" wire: do I need it? Does it need a fuse? Where is the most convenient source (best if under hood) to tap into a wire that is hot with key in accessory position?

 

2) Blue/Red "Stop Lamp Switch" wire: If I am using the Datsun brake pedal with it's switch, do I need this Blue/Red wire from PCM?

 

3) Green/Blue "Park/Neutral Position Switch" wire from PCM: what do I hook that to?

 

4) Purple/white "Output to Speedometer" wire from PCM: do I connect that to the Cable-X?

 

5) VSS wiring from tail of transmission: Is this the proper source for the Cable-X? If so, which wire do I splice off to the Cable-X - the Blue/White, or the Bown/Orange?

 

6) Orange/Black "Battery Positive Voltage" wire from PCM: Confirm-Does that go to my new fuse block thru a constant-on circuit with a breaker, or straight off the positive battery post without a breaker?

 

7) Purple "Crank Voltage" wire: does that get spliced into the same wire that activates the starter solenoid? Does it need a breaker?

 

8) Yellow "Starter Relay Control": what do I connect that to, and what is a good, accessible location to find and splice into? Does it need a breaker?

 

9) Brown "Engine Control Relay Coil Control": what do I connect that to?

 

10) Backup lights: Confirm that I simply wire the Datsun backup light switches directly to the backup light switch on the passenger side of the tranny?

 

11) Confirm: I can cut and cap the light green "brake light" wire coming fromt the PCM?

 

12) Confirm: I can cut and cap any wires labeled for the clutch or brakes?

 

I have attached pictures of my basic layout. There is one picture that shows the Painless 7-circuit fuse block on the firewall that has 4 switched circuits and 3 constant circuits. I have a remote battery in the trunk with long cables going to bulkhead connectors on the firewall. A third bulkhead connector will allow me to send switched power thru the firewall for my add-on accessories like a line lock and a 2-step rev limiter. The PCM mounts on the inner fender to the left of the fuse block. I will mount 2 fan relays to the right of the fuse block. I found an ignition switch "on" source at a wire coming off the Datsun wiring harness by the old voltage regulator plug: I connected that to the pink control wire that activates the Relay turning on the switched power circuits of the Painless fuse block.

 

Any recommendations will help. I sure thought that after sending my harness off to a service, this would be a lot simpler. Maybe you guys can help me?

 

Keith

Edited December 31, 2011 by RebekahsZ

[rsicard]

Keith:

 

Before doing anything with the modified engine harness, best to get waitformeperformance to identify each unterminated wire. They need to tell you if it needs a +12 volt source voltage or a negative/ground and whether either needs to be switched by what. They need to be explicit as to explanation for each and every unterminated wire in the harness. They need to come out with a table made up by you and then expand the table with columns explaining what needs to be done with each wire and how it needs to interface with what.

[rsicard]

Keith:

 

Suggest that you get the year and vehicle from which the PCM came from. Then to to alldatadiy and pay and download all the appropriate wiring diagrams of the PCM etc. Then use an ohmmeter and trace each unterminated wire back to an associated pin on the PCM etc. Then gather up all of this data and post here such that it can be determined what is what and what type of signals or terminations/interfaces need to be made. Also need to post wiring diagram for Cable X stuff.

[RebekahsZ]

I need you to start a harness company-waitforme has gone on strike on me: not returning phone calls, emails, etc for the past several months. After talking to other forum members, there are now better companies to work with that provide a more complete conversion package with relays and fuse blocks already installed. I shouldn't have used them and I have gotten apologies from the guys who recommended them to me-I'm not the only customer of theirs having quality and service problems. We'll figure it out. I already have the diagrams, I'm just not smart enough to read them. Also, the diagrams don't really tell me the ECM logic, to know what info goes into what and how it is processed.

 

Best I can tell from PMs and telephone calls: the LS2 harness I have can be used on a manual or auto trans. I very specifically told wait4me what I needed removed and what my application is, but it seems they overlooked my letter. Live and learn, and learn some more. I ain't giving up! Gonna post my issues on LS1 tech tomorrow.

 

KT

Edited January 1, 2012 by RebekahsZ

[rsicard]

Keith:

 

Sorry to hear your experience with waitforme. Don't understand their attitude towards customers. Came from Civilian Aviation Electronics Industry and retired after 38+ years. Everything from constructing harnesses, repairing radios to certification specialist. I understand your frustration and am trying to help you the best way I know. I am also in the process of updating and converting a 1971 Datsun 240Z to a 383 stroker Generation 1 Small Block Chevrolet. I have gone the route that you are on with the harness. I have the PCM, harness, electronic throttle body, electronic gas pedal less one last electronic box to complete the set. After spending considerable monies on these items, went with Electromotive Ignition/Fuel Injection System. A lot more straight forward system that is a LOT MORE tunable. In the process of installing Bad Dog frame rails.

 

I outlined in my last post what needs to be posted here in order that I can help sort out what is needed. You can post to LS1 forum to see what can be gained there. Best of Luck.

[ktm]

Keith, sorry to hear about your problems. The LS1 harness only needs around 8 wires connected to fire up, so the LS2 harness should not be (too) different. LS1tech has a great thread about swaps that contain links to PCM printouts, wiring diagrams, swap write-ups, etc. I must have printed out 50+ pages when I did my swap.

 

I do not have my notes in front of me, but I can tell you that the O/B wire should be connected to +12v with a fuse. You want the fuse to pop before the PCM.

 

You will find LS1tech much like Hybridz, they ask that you search first and ask questions later. I am cooking our New Years lunch today, but I'll try to look at my notes and supplement my response.

 

Edited January 1, 2012 by ktm

[RebekahsZ]

Thanks, guys. I'm picking up little snippets of info from different sources and am making progress on my body of knowledge. Really anxious for mnoel to weigh in-he knows his stuff. Cable called me and gave me some encouragement and cleared a few things up. No replies to messages on LS1tech and LS2tech. Have been busying myself with the fan and fuel pump relays. Did a rough front end alignment to make car easier to push around. Rebekah helped me! She got her Princeton application done yesterday, big load off the household. Tomorrow is Rebekah's birthday-18!

 

riscard-if you have the skills to do all this stuff, consider specializing in Z-car LS conversions. Publish a manual and make a few bucks. It is crazy that we each have to reinvent the wheel on the wiring aspect of these swaps. I'm gonna try to share everything I learn. I was a platoon leader in an AVIM - a lieutenant when I was in the Army (7th ID and 82d ABN), so I was the least proficient guy in the platoon-but i was in charge-crazy. I hated that climate, but my guys rocked.

 

Keith

Edited January 2, 2012 by RebekahsZ

[rsicard]

Keith:

 

Thanks for the encouragement. It is possible to specialize in Z-car LS conversions. More to the point, wiring is the big issue when rebuilding a Z-car. It would be best to take into consideration the 240, 260 and 280z cars. The 280Z and later wiring diagrams that Datsun/Nissan created are a big confusing mess. They made the diagrams way to complex. It would take several months to rework the diagrams into something the is a lot more straight forward and easier to follow. Then rework them again to incorporate zonal disconnects and fix up the design weak points. Next construct new replacement harnesses for the body and engine compartments that would accommodate various engine transmission combinations. First I would like to finish my 240Z and get it back onto the road.

[RebekahsZ]

OK- I'm down to the following wires that I don't have a plan for:

 

Accessory voltage wire-where to pick up accessory volts? Should this be fused?

Starter relay control-I don't know which starter relay this refers to.

Engine control relay control-I don't know what this refers to.

VSS-which wire do I jumper off of for the Cable-X box?

Stock fans, which wire is positive volts, which is ground?

 

Thanks, Keith

[m1noel]

Hey Keith,

sorry, been away for a while and don't have my diagrams with me. I do know that you do not need to hook up the speedo output from the cpu. I originally tried that but it will not drive the CableX. Use the vss out from the trans (and T-splice into it so it still goes to the CPU so it will make your speed limiter and reverse lockout work properly) to go to the CableX box +.

Good luck,

Mike

Edited January 2, 2012 by m1noel

[RebekahsZ]

Mike, thanks for weighing in, and welcome home. I had a week off, so I went a little psycho trying to get a lot done. The VSS on the tailshaft of the transmission has 2 wires; I gotta figure out which one to hook to the Cable X. Do I just cap-off the Speed sensor wire from the PCM? More to follow-let me let you get your bags unpacked. Then I really want to squeeze your brain. Fans are all wired up and work correctly.

 

Keith

Edited January 3, 2012 by RebekahsZ