I may not be correct, but I remember Durametric connects to the DME through the immobilizer. If it's throwing codes, even if they're alarm faults, you likely still have a good immobilizer and DME.

Suggest you search for posts on the "Y" connector by Ahsai:
Car won't start. Not getting 12v power to starter solenoid - Page 4 - Rennlist Discussion Forums

There's some gold in that thread Gelb, thanks.

I'll post up what I find.

Ahsai(Duncan) deserves the credit.He gives lots of help very generously.

So...

Car starts right up. I thought I'd leave a closure post in this thread in hopes that it will help someone else some day.

The problem was one of the terminals on the starter solenoid. The nut and lock washer that hold the terminal on were gone. Gone, and not anywhere laying on top of the engine.

The lesson learned here is in the method used to track down the issue. I fell victim (self inflicted really) of jumping right to the forums and searching for what it could be, instead of verifying the basics.

I steadfastly refused to believe that it was my starter motor. After all, I drove the car into the garage to replace the water pump and coolant hoses, and I hadn't had any starting issues. None of the work I did was even close to the starter (The closest I got was having the alternator out so I could get to the SAI electric change over valve).

Instead I went to the forums. Expert opinions included battery, starter switch, fuse E1, start inhibit relay, immobilizer fuse, power distributor (fusible links), pinched wire, etc.

After going through the thread that Gelbster pointed to just above I decided I had to test the Y harness and the fat cables for possible internal corrosion. The other reason I had chosen to ignore the actual starter is because it's not in the friendliest of locations.

I followed the procedure in Wayne's 101 project book to loosen up the clamps on the throttle body and rotate that portion of the intake manifold upward and gain what turns out to be really good access (for not a lot of work ) to the connections and mounting bolts for the starter. That is where I discovered the wire sitting on the terminal but obviously missing were the washer and nut.

So I reached into the zombie hardware pile and produced a starter solenoid for a 1998 Triumph T509, and pirated a lock washer and nut. I confidently put the whole mess back together, and filled it with coolant.

After sitting that long I wish I had the later style cam chain tensioners, but it quieted down quickly and didn't leak any fluids. I spent quite a bit of time bleeding the coolant system and I think I'm about topped off now.

No errors from the SAI, so once it has cycled enough times I can take it in for emissions and start looking for my next project.

Glad to hear it. I think we are guilty of this from time to time.