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Ok, I think my car is finally fixed. I had my mechanic put my old throttle body back on, and it seems good. Hopefully it will stay that way. I already was quite sure it was my throttle body that was bad, so don't look for any diagnostic words of wisdom in this message.
But here's the exciting part. I got to have a good look at how both the ISAT and TECH II tools work, and I got to spend plenty of time reading the saab TCS manual. This is very different from the one I got from Dan. There are a lot more details about how all the parts work, and just what's inside.
And here is the very important part: If you ever have your throttle replaced or you ECU replaced, or other big work, MAKE SURE THEY KNOW HOW TO DO IT SAFELY. As Anders has said, there is a code that must be sent to the ECU BEFORE YOU REMOVE THE OLD THROTTLE. It says right in the manual that if you do not do this, you could ruin the new part. Unfortunately, this warning only appears on the page with instructions on replacing the throttle body. Now here is my worry: it's easy to replace a throttle body. I fear that many mechanics would look at the book for diagnostic info, or for instructions on calibration, but it seems so simple to replace a throttle, that I wonder how many have never looked at that page. It seems to me that this warning should appear in the other frequently-consulted sections, such as calibration. The old throtle may be bad anyway, so that doesn't matter, but it seems to me that this warning should appear on the calibration page, as that would be your last chance to get the code in before you ruin the new one.
For the record:
Before removing the old throttle, plug the ISAT tool into the black connector under the passenger's seat. Go to "one system" Go to "ETS" Go to "code" Enter code 974.
An acknowledgement should appear on the screen.
Now, you can safely disconnect the old TB and install the new one. And calibrate it. Instructions on calibration are available at the Townsend Imports website.
Obviously what is happening here is this: If the old TB was out-of-spec and the ECU was calibrated to compensate, those settings could be so far out from what the new one requires that you could ruin it. This brings up another important scenario to consider: What if you decide to try a "known good" ECU to sort out your problem? That ECU is likely to be used, and is likely to still have values stored for a different TB. The danger here is the same. So, If you are installing a used ECU far any reason, make sure to run this command on it first. I believe you should be able to unplug the TB (to protect it), plug in the new ECU, send the code, and then plug in the throttle body and go from there.
I have not tried this, so it's possible that it won't take the code without the TB plugged in. That would be a problem. Not sure about that.
Anders sure is right about one thing-- it is a delicate, complicated system that few have mastered. The biggest cause of TCS problems is probably unfamiliarity. They only used this for a few years, and you may have to really search to find someone who has dealt with it a lot and has learned all the tricks. It's not only worth it, though, it's a neccesity. If you're going to live with this system, you need to really understand it, and know asmuch about it as you can find out, and you absolutely cannot take it just anywhere and expect them to get it right.
And still, one question remains: why the hell couldn't they have just used a limited-slip differential? That would actually help in the snow, unlike TCS.
posted by 4.35.68...
, Mon, 29 Sep 2003 21:23:39
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