okay peepsels
well here is the update
I boughted this tool:
http://www.etoolcart.com/scan-tool-trilingual-obd-ii-can-and-abs.aspxManufacturer: Actron
Manufacturer Part No: ACT-CP9580
Our low price: $162.29
It sells for $230 or so at local places like Autozone.
In the end, in this price range, you have to compromise something. The main consumer scan-tool makers have a strange matrix of features whereby you don't get more features for paying more, rather, you simply get different combinations of features. Unfortunately, the ability to talk to the Air Bag computer is not one of the features available except on scanners specifically for air bags... these scanners do airbags and nothing else... :-(
So basically, the main features you are looking at is the ability to do ABS diagnostics, or not, and the ability to do pre-1996 cars, or not, and also the ability to record data and play it back, or not... and also the ability to report the status of the car's IM monitors... e.g. complete, incomplete, OK, not OK. This is invaluable for troubleshooting emissions, and for evaluating a used car you are considering purchasing (hint: NEVER buy a car if any one of the IM monitors has an incomplete or not ok status unless you know what you're doing or you know you'll never need to pass an emissions test AND you don't plan on reselling the car)
Both Actron and Equus/Innova have on their web sites a comparison chart which shows which models have which features.
I went with Actron because the interface and user manual seemed on balance to be a lot more polished and easy to use and comprehensive than the Equus/Innova. It's still pretty sucky in some regards, but oh well, given the price of $160, it was by far the cheapest option that still have a comprehensive feature set.
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And then there are these nifty little gadgets:
http://www.scangauge.com/http://www.roadico.com/roadi-products.php?#turboGIIII got a scan gauge II at autozone for around $160. This thing is great. It displays an array of metrics, up to 4 at the same time, including such things as your more or less instantaneous liters of gas used per hour. The turbo gauge is similar, but suffers from the shortsightedness of the designers in that it doesn't give you real time feedback on gas consumption, making it basically useless for the purpose of adjusting your driving style to save gas.
The scan gauge lets you see so many things, including the system voltage... great for diagnosing charging and alternator problems. It even has a fairly comprehensive code reader/scanner built in, so it might be the only code reader you ever need.
I really like the scan gauge because after simply driving around with it for 10 minutes, I gained significant insight into my gas consumption, into what does and doesn't burn more gas... Invaluable, especially if you have a stick shift.. you can see in what situations shifting into a higher gear saves gas, and in what situations it actually burns more gas... coasting in neutral generally uses several times less gas than *any* situation. Turning on the A/C increases gas consumption by a third, when at idle.
The only criticism I have is that the gas consumption sometimes drops to zero when you use engine breaking... this doesn't seem like it should be accurate... But what do I know... maybe it more or less is accurate?
One caution with the scan gauge is that it would be a good idea to tape up the exposed unused RJ port. You don't want to discharge static electricity from your hand into this puppy as you could fry the internal electronics.