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Speedway Tech Talk - LS Wired!


So you’ve got your LS project all buttoned up and now it’s time to figure out if you’re going to rework the harness that came with your motor or buy a new one. Reworking an old harness can be tedious and very time consuming. Now to mention what if your harness is missing a plug? Replacement GM plugs and parts are super expensive!

Speedway Motors offers its own LS harness and also carries the Painless Performance brand. Both harness’ have quality wire and OE type connectors. Each connector is tagged so you know exactly where they go and this makes hooking up your harness a piece of cake. Instructions are also included and are very detailed about what each plug does.

What’s great about this harness over a reworked harness, is the fuse block. If you’ve seen a reworked harness, they only have 4 fuses for everything. These wiring harness’ from Speedway Motors and Painless Performance have a fuse for each circuit. The injectors, the coil packs, the fuel pump, etc, all have their own fuse. This makes it really easy to figure out any issues with fuses, if something were to come up.

Are there any changes to be made to the PCM? Yes, before you go and plug in your PCM, you will want to take your PCM (computer) to a tuner. Your tuner or shop will delete any VATS (vehicle anti theft system) codes and help dial in your cars setup for its maiden voyage. Without deleting the VATS your car won’t start. This harness also deletes all emissions and EGR plugs if your year of LS had them; your tuner will adjust for this as well.

Which transmission will this harness work on? If you have an early LS that had a 4L60E, then you’re in luck because each harness is setup for that transmission. If you have a 4L80E, you can reroute the pins in the transmission plugs to make it work. There are a couple websites online to help you with this issue.

If you want to hook up your LS to that old fully mechanical 3 or 4 speed automatic transmission, you can use this harness as well. You can either leave the 4L60E plug in the harness and just hide it under the car or de-pin the main plugs to the PCM and take it out altogether. If you want to use the older transmission, just make sure to tell your tuner, so they can program the PCM for this change.

The Speedway Motors harness has a life time warranty on the workman ship and quality of the harness. You won’t get that assurance out of a 10 year old reworked harness. Be assured that when you hook up this harness, you won’t have to worry about whether or not something was hooked up wrong or now. Just pull this harness out of the box, plug in the plugs and apply power to the fuse block and you’re good to go!

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