It's not to test or connect up to the ECU I don't think, I wouldn't mess with the ECU unless you're a real mechanic and you know what you're doing, it works on 5v if you hit it with 12v you will be spending over $400 US for a new one, go figure
look for bad connections first, I hear they normally don't go bad, unless you were disconnecting and connecting with the battery connected, that's what I did, I have a touring and the speedo is on the tank, so I was just removing the tank and forgot to disconnect battery, when I plugged it back in it probably spiked, be very careful testing, I don't think it says to use the ECU, maybe a 5v signal wire from external source??? But I would look for chaffed insulation and broken wire underneath motor, do you know where it's located??? When you're talking ECU $135 for new road speed sensor doesn't sound that bad and if it's not you have an extra!!!
Are you a seasoned mechanic?? I'm not, I'm a shade tree mechanic, operating engineer by trade, I've done a few different trades, 1 year of basic electricity in HS, so be careful, at least it runs good now
I would even be scared to do that cleaning method with vinegar on the ECU, if it looks clean, they are sealed pretty good, leave it alone, I don't even think I put dielectric grease on the ECU
Look for used or new discontinued parts, I found a few, the disk rotor bolts you can get on ebay, titanium, but you have to replace them all cause the weights are different it will mess with the balance, I bought like $400 in used parts already just in case, I have most of the sensors and the TB's complete., I was looking for a windshield lock, discontinued, so if anyone has a spare hook me up