Wiring

Wiring is the most year-specific part of an LS Gen Coupe swap. Colors and pinouts change between BK1/BK2 and 2.0T/3.8 models, so verify with a multimeter and your factory service manuals before cutting or splicing.

Shop manuals & wiring diagrams: Google Drive folder (all years/models)

Related wiring lives on its own pages: fuel pump relay, radiator fans & relays, alternator, A/C, gas pedal, and VSS / speedo.

Passenger-Side Fuse Box

Note: If you want to keep the factory A/C function, depending on how you wire the new engine ECU, keep the passenger-side fuse box and the stock ECU. Otherwise check the A/C page for details.

The main wires you will need from here:

  • Large pink — wire this directly to your starter.
  • Red/white — the OEM fuel pump power wire. Use it as a trigger wire: attach it to the Holley green FP wire if you already have a dedicated FP relay. You can also find this wire near the driver's kick panel if you don't want it in the engine bay.
  • Large red — several switched-on 12V feeds. Leave a few open for easy access down the road (relays, accessories), or just tap a fuse.
  • Twisted red/blue pair — CAN bus. You most likely won't need these.
Wires pulled from the passenger-side box: 12V, FP, A/C, CAN, and starter.
Harness opened up — the large pink starter wire.

Some people open up the whole harness and pull out the extra wires. Personally I just capped the extras and wrapped them back up — it looks just as clean, but it's up to you.

Push to Start

The pink starter wire provides 12V when you press in the clutch pedal and the Push to Start button. It attaches directly to the small stud on the starter.

On some other starters the pink wire won't work by itself — you first have to ground the starter relay, then use the pink wire to the starter.

Pink push-to-start wire routed toward the starter.

Holley 12V Power While Cranking

A Holley Terminator X setup needs 12V power while cranking. Use the driver's-side fuse box, 2nd row, third down, labeled ECU power — the Holley ECU power wire goes here.

Fuse tap in the driver's-side box ECU power slot.

Automatic Reverse Lights

"Wired up backup lights for T56. Used a short reverse sensor from Sikky and a pigtail. Used it as the ground switch for the backup lights relay on the driver's-side fuse box, so one wire ground, one up to the switch side of the relay. There should be current going to the relay. I spliced the always-on 12V for the relay to also act as the positive side of the switch. Relay numbering perspective is top-down, as if you took the relay out and are looking at the female connectors."
  • Slot 1 spliced with slot 3
  • Slot 5 goes to the reverse switch
Reverse light relay location.
Reverse sensor harness.

Manual Reverse Lights

Manuals should note the reverse switch connector on the OEM transmission if you want to reuse the passenger-side fuse box relays or wires. (No pictures or pinouts for these yet.)

If you have a T56-variant transmission and no passenger-side relay box, simply run a long pigtail so the reverse lights work when you shift into reverse. Run a fuse power tap from the driver's-side fuse panel (seat heater shown below) to the green side of the reverse switch on the passenger side of the transmission. Then take the black switch lead and connect it to the corner white wire under the driver's kick panel.

Driver's-side fuse panel — tap the seat heater fuse for power.
Rear view of the in-cab fuse box: tap wire #12 (may be grey or red/black).
Pigtail made for the T56 reverse switch.
Muzzy's T56 pigtail set (back-up lamp, lockout, VSS).

2016 BK2 might be this wire — the gray wire at the tail light is reverse; provide it with power and it lights up:

BK2: gray wire at the tail light is reverse (unconfirmed on all years).

Automatic Torque Converter Unlock Signal

Terminator X brake light switch hookup for BK2: run the grey wire from the Term X transmission harness to the red/black wire from the brake switch.

Brake switch connector.
Stop lamp switch diagram.

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