ECU jumper harness

[evolutionmovement]

So we have a pinout diagram for the EJ22T ECU. Do we have pinouts for other ECUs? EJ20, EG33, etc.? I was thinking that since I'm going 4-wheels for my Tigershark project and this great rwd transmission option opened up that I might want the option of changing from the performance-efficiency mantra to efficient-performance and back again. I think an EG33 could fit nicely.

What if we had the pinouts for both ECUs and could make a jumper set that would switch all the necessary wires from whatever your chosen base harness would be (eg, EJ22) to whatever your optional engine ECU would need (like the EG33)? So, say you wanted to swap out the EJ22 with the EG33, you'd remove the ECU and have a short (say 8") set of wires that would connect from the EJ22 harness using an old ECU connector to the new ECU with whatever connector it needed. To take care of the engine side of things, you'd have a harness that stayed with the engine and plugged into the main harness in whatever way translated to working with the ECU (I hope this makes sense). In my case, I found these great firewall harness plugs that I'd use. This way, I'm thinking I could swap out the EJ and the EG mechanically in a few hours and the electrical could be handled with just a couple plugs. I'll have to think of a way to make the exhaust easily swappable, but I don't see that as a big problem and that's not relevant to this discussion.

Not sure if this idea would help anyone else, but I thought I'd throw it out there. Plus, if anyone thinks of something I'm missing as to why this wouldn't work, that would be useful, too.

[Legacy777]

Fabricating those plug and play harnesses is easier said than done. Removing the ECU plugs is not an easy task and they are very fragile. What you want to do I'm sure could be done, it'd just require a bit of patience to get everything figured out.

[93forestpearl]

Josh, I don't think you tried it, but blasting the board with a torch made it come right out perfectly intact.

Actually using the pins in a reliable fashion is another story, however. The pins on the ECU header are meant to be rigidly soldered to a printed circuit board, not soldered to wires. Some sort of epoxy support would need to be made so the pins do not fatigue and break.


If you do not plan on ever returning the harness to stock, don't waste your time. Buy a bunch of heat-shrink crimp connectors and a ratcheting crimper and be done with it. Ebay is a great place to buy said connectors, in the well known 3M brand. I bought 200 of them in my choice of sizes for $40.

On soldering vs. crimping. Take apart a factory wiring harness and find me a soldered connection. You won't. A properly crimped connection will rip the wire before the crimp fails. Soldered connections can fatigue the wires strand by strand until they break. Not saying I never do it myself, but my stereo wiring is a little different than my crank angle sensor.


Food for thought.

[Legacy777]

Yeah I never tried the blow torch method. But you're right, the pins are rather fragile and meant to be secured in a PCB vs. just having wires soldered to them. They would definitely need to be encased in epoxy or something similar to help provide some rigidity.

[evolutionmovement]

Do we not have any sources for new plugs? OK, then what could be done as well is to use the connector of your choice for the master harness and make up a jumper set for each ECU. That way, all you'd need is a length of the main harness from the donor car of each engine and wouldn't need to take apart any of the old connectors.

[Legacy777]

You should still be able to find the plugs as they were used on other cars, and not to mention Link used them on their G2 & G3 ECU's.

[93forestpearl]

About a year ago I did find a place that sold the ECU headers new in the UK for a lot of money, like $150. Not worth it in my opinion.

For the money you would spend on new stuff, you could get the tool and pins to re-pin the factory plugs that go into the ECU header.

[evolutionmovement]

Why would I need to re-pin the factory plugs? I would have two sets of cut off harnesses, each with a factory plug. Actually, I could just leave them plugged into their respective ECU's and never take them off, removing the worry of old connectors. These cut off harnesses would only be maybe 8-10" long. On the cut end would be a plug of your choice which would connect to the main car harness. Each of the cut factory harnesses would have to have their wires arranged in the new connector so that they connected from whatever pin was chosen for what on the main harness to the appropriate port on the ECU. For example, say you put the crank position sensor on pin 4 for the main harness. And let's say the EJ22 ECU wants the CPS on pin 4 as well. No problem—the wire just goes straight across. But maybe the EG33 ECU wants it on pin 8. So the jumper for that ECU would go from pin 4 on the main harness to pin 8 on the ECU. Now when you swap engines out, the electric is as simple as unplugging one ECU and plugging in the other. I suppose if there's the room, you could just leave both ECUs mounted under the dash and just swap the plugs. There's a little extra weight, but might be less of a pain than mounting and remounting ECUs.

[OddBallRacing]

Do you know anyone with AllData? You should be able to find all the wiring diagrams you need in there. I found that the diagrams I got off the interwebs were inaccurate yet the ones I got out of AllData were correct.