Hi guys, I need a few answers, that I know have been asked thousands of times. I kind of got suckered into helping a friend here, and when I agreed to it I had no idea what I was getting into.

A good friend of mine is swapping a 1jz with vvti from a chaser into his sc300, and asked for my help with the harness. Sure, I thought, can't be too hard. Now I have been searching for days and days, and still have not gotten anywhere. I have found some pinouts and vague information, but I am still missing one big point. What in the hell has to be done, exactly. I have read, and read, and just keep getting small pieces of the big picture.

So far I do understand that there has to been an extension, and body plugs don't match, but apparently, it's not that simple? I just need to know where to start. I am an experienced auto technician, and have done my fair share of engine swaps in other make cars so I do feel comfortable that if I can get good information on what's going on with this swap I can make it happen.

Car is staying automatic, I have the original sc300 harness, and the chaser harness, chaser ecu. Can anyone help me?

 

Chaser motor, Chaser ECU, Chaser harness. Those are key pieces. I didn't do my swap from a Chaser so someone can chime in on the Chaser specific stuff. (93 Soarer R154 > 92 SC300 W58 swap here)
For the ECU end, all you need to do is extend the harness assuming you want to have the ECU sit where the factory ECU is. For the body harness, you need to find what colors correspond to what pin on the Chaser ECU and harness. Then compare to that the SC harness pinout is on the body side. Swap around the pins that are in the wrong spots on the Chaser side. Plug into the SC plugs. Presto. Finito. Somone on here probably has the Chaser pinout to help you out. You probably already have the SC pinout for your car. If not, pick up the electrical manual for your specific year car. You WILL use if pretty often for and after the swap.

 

Solid stuff. I appreciate that. I can print the SC pinout from work and probably the body plugs, too. If I can't I know someone at a lexus dealer that can.

 

Maybe it's a dumb question, but as far as the engine harness, is it just the wires for the 2 ecu plugs that have to be extended? are the body plugs to be modified part of the dash harness, or are some of those connectors on the engine harness? sorry to sound like a noob, lol, just trying to get as much info together before really getting started. thanks in advance

 

the body plugs that need to be re-wired and extended are usually hanging out by the ecu connector, or within a foot or 2 of it, they connect to places under the dash. also there is a spot where it connects to the fuse box in the engine bay, not sure if that is the same plug/wires or not but those also need to be sorted I think there are only a handful of wires there.
definitely not the easiest of harnesses to start learning on.

 

If you have both harnesses, what's the problem?

You look at the stock harness/diagrams.

You also can use the stock harness as a jig, because that's what your new one you're making should generally look like/fit like

You figure out where it gets power to the stuff that needs power, and make the stuff so it can receive said power in the same place as the stock harness

You figure out what needs to be done to make the cluster receive the oil/cel/temp/tach/speed stuff from and put it there. Tach wire will come from igniter.

You basically tear the chaser harness apart, verify where all the **** is that transfers over like cluster functions are and label. Then apply it to the new locations.

Basically Toyota to Toyota swaps are easy as ****. Everything circuit-wise is basically labeled the same, so just find where its at on one harness, apply it to another.

All you're doing is finding where all the **** gets power/interfaces with body, then moving it around til it fits like stock in the Lexus. Its really that easy. Anyone that tells you its better to start with a soarer harness and to locate one is both lazy and retarded.

 

Pro Tip: do NOT listen to intamzy or whatever his name up there is and go by colors at all. Colors tend to be different between chassis types sometimes. It can get you a one way ticket to cluster****ville, quickly.

Use continuity and labeling to keep track of circuits. With wiring, NEVER assume, especially if you're not familiar with it.