Under dash wiring from donor vehicle

[fastlane]

I bought a 03 express van for the LQ4.i was working on removing the wire harness this afternoon with my son (7, took 3 times as long but we had a good time!) I did not cut anything accept the headlights (corrosion) I disconnected the wires from the CPU and took apart the fuse box. What do I need under the dash? I'm assuming the OBD port. What about the ignition?

It's not in great shape, it's got a spot that rubbed against the motor and quite a few areas right near the CPU have rubbed through, I'm really considering a new standalone harness, but my budget would like performance parts! Performance parts that would be useless if it doesn't run! 😂

[prodjay10]

I only took the engine wiring. Then made a fuse / relay box like suggested in lt1swap. If you have the obd2 connector you can reuse it. I bought one from China for about $3 but took forever to get.

You can repair that wiring. Solder new sections in or just wrap them if only the insulation is compromised.

I don’t think you need the ignition switch/key. Once vats is removed from the ecm, you can wire the starter from the key/ignition on the truck it’s going into.

I used the purple starter wire from the donor harness and soldered it to the purple wire from switch the motor is going into. Works like a charm. Just no security.

[MDPotter]

If it's an 03 LQ4, it's drive by wire so you'll want the throttle pedal and the harness that goes from the TAC module to the pedal. Other than that, everything else should be in the engine bay. Engine harness, PCM, TAC module, and all associated connectors. Just buy a new OBD pigtail and a simple 2-wire check engine light.