Adapting parts of current wiring to VH45 harness

[tmorgan4]

The one thing holding me back from this project is wiring, however I think once the engine is in I will be able to figure things out with everyone's help on here.

In a recent post, it was mentioned that the only things needed for the engine to start (to START, not run correctly) are:

Switched power from the ECU relay into the ECU

Starter signal

Fuel pump signal

Positive power to the following:Injectors ( its a seperate wire on the engine harness)Coil packs (its a seperate wire on the engine harness)

These are inter-connected:TPS sensorO2 sensors MAFCrank angle sensorIdle air control valve

Instead of ripping out every inch of my current VG33 wiring harness, I am trying to figure out a way to utilize parts of the factory wiring and adapt this to the Q45 ECU. This would include the switched ECU power, starter signal, and fuel pump signal. I have downloaded both the Q45 and Pathfinder FSMs and tried comparing the ECU wiring schematics but it's extremely complicated.

I would like to remove the pins in the Q45 wiring harness for the switched ECU power, fuel pump and starter signal and replace these with the current wiring to save myself some work.

How does this plan sound? The majority of the rest of the wiring appears to be fairly "self-contained" on the engine itself.

The FSM diagrams also mention lots of plugs for the TCS system...is it MUCH easier in the long run to source an ECU from a vehicle without TCS or can I simply leave this plugs unhooked (or cut them off???). I would appreciate it if someone who knows much more than I do would be willing to talk personally with me about the ECU schematic diagrams.

This Pathfinder is waiting for a V8.

[RichZilla]

Here's what you need to do: Remove the VG33 loom - unplug it from the dash and ecu. Pull it out through the firewall and leave it connected to the engine. There will be one or two plugs that connect to the car under the dash. Work out what these wires do.

Things like:oil lighttemp guagebattery positivefuel pump relay signal (from ecu)alternator charge lightmain relay signalcoil or ignition positivetacho signalspeed signal

Then work out what wires in the plugs on the VH loom next to the computer do. Draw pictures and use those to connect what's required. Don't **** around trying to save/use the vg33 loom. Its far more work.

I've still never wired up a VH45, but I've wired many engine swaps before. And that process is pretty much the same no matter what the car - except for Subaru where the engine loom is in the body loom.

Oh and with the TCS plugs, Leave them plugged in on the motor for a cleaner look, but obviously leave the TCS computer out.

[tmorgan4]

Unfortunately I've already pulled the VG33 so it isn't going to be quite as easy to trace each of those wires and figure out where they go. I do have the Pathfinder FSM that I can research which plug is what and still try do to what you are saying. Sounds like good advice to me!

[T45]

On the Q, the engine harness is completely separate from most of the rest of the car. I believe the VG is the same way. Once you pull the engine harness back to the ECU you'll see that 90% of the wiring is between the ECU and the engine, and that there are only a few that run to the dash, ign, trans, etc.

Once you pull the engine loom all the way back you will then be able to see what wires go elsewhere and then you can trace them out with using a pin out schematic or using color codes.

[Geoffs89Pathy]

im at the same point with mine. got a 1989 pathfinder. i have a 1995 Q45 that is donating it engine to my pathy. some help is needed...