Wiring non-Toyota engine into Toyota platform

[IowaOffRoad]

I'm swapping a 1996 Dodge Magnum 3.9L into a 1993 4Runner (don't bother talking me out of it). I would like to maintain as much of the Toyota controls and instrumentation that I can. I can do this myself, but it will definitely be a time-suck. I was wondering if anybody had any experience out there with companies that specialized in this. Hotwire offers a 3.9L Magnum stand-alone wiring harness, but that's not exactly what I'm looking for. I would like to send the engine compartment side harness off the 3.slow and the Magnum off to someone and have them splice away. If it was an LS into a squarebody this wouldn't be an issue, or a 3.4L into this same rig, but I've convinced myself this is what I want. I'm also cheap, so perhaps this is more $$$$ than I'm willing to trade for my time.

Also, does anyone have a link to a decent wiring diagram for a 1993 4Runner with a manual and a 3.0L? Interwebs isn't giving a lot without paying some Russian bot...

 

[Chkn]

Probably easiest to run a stand alone harness to control the 3.9L. Then add the extra Toyota sensors to the 3.9l so that the Toyota instrument cluster works.

 

[IowaOffRoad]

Probably easiest to run a stand alone harness to control the 3.9L. Then add the extra Toyota sensors to the 3.9l so that the Toyota instrument cluster works.

That was my plan for engine temp and oil pressure if I do it. I'd like to run the Toyota fuel pump with this engine, the factory pressure output tolerance falls over each other. The interwebs has conflicting information, but the nominal pressure for the 3.9L is 44psi, and the nominal pressure for the 3.0L is 41psi, so I'm hoping to wire in the fuel pump control from the Magnum ECM to the Toyota pump.

ETA: thanks for the info

 

[rockota]

I agree on standalone + what is needed for Toyota dash/etc.
Did a 4.3 TBI in the 90's... but I think that was all of 4 or 5 wires. Temp, oil pressure, tach, start, power? Ran a Howell harness and plugged in toyota where needed.

Completely easy by comparison to what you're trying to do.

 

[Ghetto Fab.]

Thats pretty much how you have to do it, make the engine a somewhat stand alone setup, then try to connect the toyota stuff to it where needed. When I did my 4.3 swap that how I did it. I reused the toyota oil and temp sensors to work with the toyota dash and adapted them to the GM engine. The tachs on the toyotas are adjustable so as long as you can get some kind of signal that will most likely work out. Typicaly the engine system will have an output to turn on a fuel pump relay, so use that to turn on your toyota pump relay. The power distribution side can be a bit of a pain, but I also think it can be dumbed down a bit better than what I did. Honestly the biggest issue is getting things like the AC system to work as the toyota setup is a bit unconventional. I also have yet to figure out how to make the cruise control in mine work.

You need Alldata or Mitchel subscription to get good diagrams of both vehicles. I think they still offer a novice or hobbyist subscription price. If you know anyone that works at a shop you can also have them print off all the wiring diagrams.

 

[Oddball]

Yotas are dead simple. Don't over-complicate it. Above the ecu there is a plug or two. Everything for the dash is there. The circuit open relay is also there. It operates the fuel pump (Blue wire). Speed signal to the ecu and tach might be your only hang ups. If it is a cable speedo then the pulse gen comes from the cluster. So just yank all the toyota crap except for the dash harness and pigtail. Install the new engine, harness and ecu, and use the toyota fuse box for power.