Soldering question
 

I was about to install my MPGuino, and after some difficulties finding the ECU to tap into (every diagram I could find showed it at the top of the glovebox, so image my surprise when I found it at the bottom) I tried locating the wires I'd need to tap. I've got some rather detailed schematics and pinouts, but the problem is the wires themselves.

I honestly don't think I've ever seen electronics with wires this thin. I had some 22-24 gauge wire ready to go (and some cheater clip taps) but the wires coming out of the ECU are about the size of half the actual cable including the insulation! Clip taps are totally not going to work at all, so I guess I really need to solder the taps in but I don't know if I'll damage the cable irreparably by trying to solder them...

I'll get a pic up in a few for comparison, but should I be worried about damaging the cables or am I just being paranoid?

You should be fine, just be careful stripping the area you want to solder. The wire is still metal, it'll probably just heat up faster since it's thinner.

You could also cut the wire, and crimp connections onto the end. Soldering is definitely the more secure way to go, as the crimped connections have a way of falling off after a while, but either way will work.

If you're worried about damaging the wire, then cut open a spot far enough from the connector that you could still crimp a connector on there if you had to. That way, if you can't solder it, you still have the option of putting connectors on there.

Here's some pics:

This is the front of the ECU (ECM as toyota calls it). As taken by my phone, upsidedown, about 6" from the floor which makes it pretty darn awkward to work on.
http://ecomodder.com/forum/attachmen...1&d=1229029402

Here's where the ECU is located from a more upright position:
http://ecomodder.com/forum/attachmen...1&d=1229029402

Do you see it? Me neither. Took me almost 20 minutes to track it down by following the bundles. And then there's the "clips" that hold a cover over it that took another 10 minutes to remove (it appears they were designed to be 1 directional).

I don't know if the pinout image I have is positioned upside down or not, without a flashlight to be certain, but it looks like it is. I was going to try to put a regular wire next to the ECU wires for comparison, but no light = fail. The next problem, or rather the pre-curring problem, is that the wires are bundled so tightly I don't know if I can separate them enough to actually get in there to tap them without starting a fire.

But that's slightly easier to get to than the fuse box... What ever happened to cars being easy to maintain?

Cars that are easy to maintain don't bring in 120 bucks/hour at the stealership shop.

Could you possibly considering sourcing the signal from sonewhere else? I wouldn't work in that tight mess... maybe you can pick it up near to the sensor, where the wire enters the car in the first place, near the fuse box... somewhere other than that ratsnest.

Would it be possible to piggy-back the wire into the back of the plug going into the ECU ?

It probably depends on the design of the plug but a Molex or similar sort of plug connector (just the metal part) on the end of the wire might push into the back of the ECU harness plug.

I used to love the taps but now I hate them. They work good for awhile, but Ive had too many of them work loose over time. Once was on my trailer brakes. Anymore I always strip and solder and tape. I only want to do the job once, especially in an area as hard to get to as the ECM.

I might be able to piggy-back the ECU connection at the plug. From the outside it appears to be a molex-like connection. I've got some free time today so I'll see what I can do with the rat's nest.

I just realized I left my color printouts of the schematics at work. I hate printing things out; too bad my phone can't read PDFs yet.

Nope, no piggy backing option. Waaaaay too tight in there.

In any event, I finally got the wires tapped (I cheated and used the taps, I'd need to wait till spring at least to get everything set up and I got impatient).

I'll very likely go back and solder once spring or summer rolls around.

And a few weeks later:

How does one go about de-soldering? I've seen kits with a soldering iron and what appears to be a large metal turkey baster, but what is actually involved? Do I need that type of setup?

Two ways to go about it: one is the solder sucker, which is like a small turkey baster. Heat up the solder and suck it up. The other is solder wick, which is braided copper. Heat up the solder with the iron, touch the wick to it, which absorbs the solder, and then cut off the end of the wick to expose fresh wick.

I haven't had to desolder yet, so I don't know which is better.