Joel,
Crap, I just wrote a long response to your last post, hit some random key on my computer by mistake, and wiped it all out. AAARRRGGH!!!
OK, here goes again, from the beginning:
I follow most, but not all of what you're saying. If it's true that a mis-gapped, incorrectly connected, or non-functional speed/reference sensor would not result in the DME outputs not working (as indicated by my CEL not blinking when I try to do a blink test), then you're right that pulling that thing out of that very tight spot and re-gapping it would be a waste of time and knuckle blood. I was focusing on the lack of tach needle bounce as a major clue, but maybe I'm over-emphasizing that.
As far as the alarm, doesn't the fact that I'm getting +12V at socket 86 of the DME relay connector in the fuse box, and that I'm getting +12V at socket 18 of the DME connector whenever the battery is connected, and +12V at socket 27 when the key is in the start position, argue against the alarm immobiizer being responsible for my car not getting any spark? I don't know exactly how the immobilizer works, but logically, I would think it would kill the flow of current to socket 86 of the DME relay, because this socket sends current to the coil within the relay that closes the switch that completes the circuit to send current to the DME. And even if it is the alarm module, I don't have any idea as to how to bypass it, because there's zero information on any of the forums as to how to do this on a 968, and I'm not knowledgeable enough about electronic componentry to figure it out from the wiring diagram.
I did check the voltage at socket 7 in the DME connector (although the manual says this socket is for the air mass sensor - I don't see one listed for the alarm), and it reads 0V with the key in the start position. As far as testing whether my alarm is working, I know this is a stupid question, but how would I do that? I don't remember it every going off since I've owned the car.
I do agree that figuring out why my CEL doesn't flash on and off when I try doing a blink test should be my top priority - I just wish I had some ideas or leads on how to do this. I was hoping there might be a connection between my lack of tach needle bounce and the speed/reference sensor, and that this could somehow cause a lack of output from the DME, but your opinion that there probably isn't actually makes sense. And doesn't this rule out checking every other input signal to the DME (most of which have to be tested with an oscilloscope with the engine running, anyway)? In other words, the blink test is designed to test if these sensors and components are working, so I can see that it doesn't make sense that one or more of them not working would cause the blink test to not function.
If it is a bad wire somewhere in the harness - holy crap - anybody in the market for a 2800 lb paper weight? Seriously, I was very careful with the harness while I had the engine out of the car, for the very reason that I wanted to avoid causing the type of nightmare I'm now living. The fabric wrap had come off most of the harness, so I carefully re-wrapped it in that flexible accordion plastic sheath material, which I wrapped with a zip tie every few inches. This gave me the opportunity to inspect every inch of my harness, and it looked to be in very good shape. Also, the recent testing I've been doing has been with the DME and its harness laying on the passenger compartment floor (there's no seat in the car), so if a wire were kinked, it shouldn't be now.
Any ideas on how to figure out why my blink test isn't working would be greatly welcomed. Thanks.