I am going to do the LS4 Swap and lol I hate wiring. Can you help me answer some wiring ?s. As far as im concerned wiring is hardest part and lol i totally despise doing it. I have a low mileage LS4 engine but no trans yet. I want to use a 4t65eHD. Does the 4t65ehd have an internal back up light switch? Where does the stock fiero automatic have its back up light switch? I WONDER IF A RANGE SWITCH LIKE A 4L60E has HAS WILL WORK ON A 4T65E If so that's easiest way I think to wire bu and neutral safety for an aftermarket shifter. Its been super cold here so I have not been able to get Fiero on lift yet to look as much as I want. My car is an 88 notchback. I'm using an MSD 6014 for my LS timing and I will need a hot when switched wire and clipping into an already fused wire worries me even if I do relay it. I'm assuming I can re use existing fiero alternator, starter and ac wires. I will not be using the fiero ecm however i'm not gonna remove it. I'm assuming I can reuse engine accessory connection wires. And if I want a switched hot and constant hot wire where is the best place to find them so I can hook up the pictured leash relay board.
Wiring isn't that hard. Each wire only has two ends.
........and if I may add, the easiest way is to check, measure, cut and hook up only one wire at a time. You will need the connector pins and a crimper to attach. Start with a stock harness and work from there. As for the transmission the LS4 PCM will control the 4T65eHD. No need for paddle shift. There are quite a few guys on this forum that have done this swap and will be able to guide you in the right direction. You will probably want to change the cam and remove the AFM (DOD) parts.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
........and if I may add, the easiest way is to check, measure, cut and hook up only one wire at a time. You will need the connector pins and a crimper to attach. Start with a stock harness and work from there. As for the transmission the LS4 PCM will control the 4T65eHD. No need for paddle shift. There are quite a few guys on this forum that have done this swap and will be able to guide you in the right direction. You will probably want to change the cam and remove the AFM (DOD) parts.
Oh I can do it lol I just hate it. I already have trans control and timing controls..In my 33 ford I wired it from end..to end and even made digital gauges and an rfid start..but im just saying lol it is no fun at all..if anyone wants an rfid start i can tell u what's needed to construct one on the cheap ..just yell..thanks
Wiring isn't that hard. Each wire only has two ends.
And a thousand different places that it can go.
------------------ Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.
Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.
I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 4-wheel drifts are fun!
One wire from engine to PCM can go in only one place. If you are talking about a swap harness many of the wires are already connected. On a basic harness you just need to change maybe 15 wire connections to get everything to work. On my first 3800SC harness we only had to make about a dozen changes as we retained the GTP power center. It wasn't that hard and it took only one evening.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Since I have built a few harness, I can tell you that once you get all the pinouts, and all the wire diagrams for your motor and the stock Fiero, its not that bad. What folks don't understand is that the engine harness is already done. From the PCM to the sensor, its not changed. For the most part, (95%) you don't touch the engine harness, its the portion of the harness that leads into the cabin and connects to the Fiero harness. Some swaps have the fuze box in the engine bay, in the Fiero its under the dash. What your doing is connecting the wire from the swap to the same location in the Fiero. In the end its usually only 15-20 wires that you need to "fix".
My first Northstar swap harness had 150 wires. I think a fully wired V8 with sequential injection, coil per cylinder & throttle by wire would be around 180 wires. I've done a dash harness for a Pontiac 6000 STE digital dash that was 230 or so.
Sooo.... not 1000
[This message has been edited by Will (edited 01-22-2021).]
One wire from engine to PCM can go in only one place. If you are talking about a swap harness many of the wires are already connected. On a basic harness you just need to change maybe 15 wire connections to get everything to work. On my first 3800SC harness we only had to make about a dozen changes as we retained the GTP power center. It wasn't that hard and it took only one evening.
quote
Originally posted by qwikgta:
Since I have built a few harness, I can tell you that once you get all the pinouts, and all the wire diagrams for your motor and the stock Fiero, its not that bad. What folks don't understand is that the engine harness is already done. From the PCM to the sensor, its not changed. For the most part, (95%) you don't touch the engine harness, its the portion of the harness that leads into the cabin and connects to the Fiero harness. Some swaps have the fuze box in the engine bay, in the Fiero its under the dash. What your doing is connecting the wire from the swap to the same location in the Fiero. In the end its usually only 15-20 wires that you need to "fix".
Rob
Very much depends on how neat you want the finished harness to look. If you're putting a lot of effort into making the swap look neat, then you're going to want to build the harness wire-by-wire in order to get the routing and lengths of all the wires "right".
Just like everything else... if you don't care how neat it is, you can do it quickly and cheaply.
Originally posted by Will: Very much depends on how neat you want the finished harness to look. If you're putting a lot of effort into making the swap look neat, then you're going to want to build the harness wire-by-wire in order to get the routing and lengths of all the wires "right".
Very much depends on how neat you want the finished harness to look. If you're putting a lot of effort into making the swap look neat, then you're going to want to build the harness wire-by-wire in order to get the routing and lengths of all the wires "right".
Just like everything else... if you don't care how neat it is, you can do it quickly and cheaply.
True, my last harness I pulled each wire out of the PCM connector, routed it for a clean look and in the end it was 100% custom, but in that case its still pull from C11, reroute, put back into C11, (cut/crimp or just fold). Its not difficult, just time consuming. You still only have to "figure out" the 15-20 wires that join the two harness together.
I relocated several plugs and rerouted the harness to clean it up. I also relocated the fuse relay box to the front spare tire area. I did not count the splices, but it was approximately A LOT. I am happy with the LS4. I love the sound most of all.
