I’m sure the ground is there if the car is running at all, it’s what your ecu is primarily grounded to. The thermostat housing is where the lower radiator hose connects to the block, you can see it kinda to the lower left of the distributor as you’re looking at the transmission side of the engine, it’s towards the firewall. If you look closely, you’ll see a bolt towards the top of the fittting where the radiator hose connects that should have 2 wires on it (I think it’s two…), that’s the main ecu ground, among other things. It may be a bit hard to see at first, you have to know what to look for. I just realized you aren’t the same guy with the intermittent starting problem, which is what this ground can sometimes cause if it’s loose 
I’m not sure what the problem could be exactly. Check ground G201, it’s the S4 switch ground, I’m wondering if maybe that’s the problem, or at least some point in the wiring from the s4 switch to the ground. G201 is the ground for basically the front lights (fog/head/turnsignal), as well as the s4 switch (and a couple other things). It’s in the front of your engine compartment on the passenger side, it should be a white connector with a bunch of wires going to it. It’s kinda in between the radiator and the back of the passenger side headlight, mounted on the front part of the chassis. You may have to move the battery to see it, I’m not sure. Also, you can check for ground at C434, which is a 2 wire white connector that is located under the center console near the shift lever, it is to the left of the big 10 wire white connector coming from the shift position console switch. I think C434 is connected to the 10 wire connector (C726), and is the lower of the two 2 wire connectors. The black wire on it should be the ground, so check for continuity to ground. Well, I’m getting tired of going through the helms for tonite, hopefully one of those grounds is messed up and will fix your problem, good luck! And definitely look into getting a helms, they are invaluable, all this info is easily available in them.
thanks for the info man…and yeah…i ordered my helms last night with next day delivery…im afraid if i drive it much longer without s4 im going to burn my tranny up and CEL has just got to go. Anyhow…thanks again.
Thanks for the info, I am still reading the posts, and having the some of the same symptoms as G2IncrediTeg, but my s3 only blinks when the car won’t start. When it finally does start it goes away. I am in the process of checking all of those grounds now, and will let yall know what I find. Again, thanks…