Read through this, it is for a different car but the same engine and engine managment system.
http://www.gomog.com/allmorgan/GEMS/GEMSbyPoole.pdf
It tells you how to turn the engine over without starting it, there is a button under the hood on the firewall somewhere.
It is there to test compression without cycling the whole ECU.

 

That sure is intresting reading Spike, thanks I saved a copy for future reference. Is that the same for my 97 Disco?
Bob

 

It is forall GEMS engines. The engine in the link is a 2001, but nothing has changed from then to now. A GEMS is a GEMS. They are pretty bullit proof and simple. Everything has a default mode, so if something fails the engine will still run, might run like crap, but it will get you home.
The only thing without a fault mode is the crank sensor.
That also lists every single fault code in the OBDII system.
If you read the whole thing it will tell you everything you ever wanted to know about the GEMS engine management system.

 

With that being said, does it seem like a good idea to buy a sparecrank sensorto put in the glovebox (especially since myDiscohauls the baby around)? It sounds like these things are known to fail on occasion and it could really leave you stranded. I only looked quickly, but it seems like the D2 sensorsmight be a bit more expensive. How hard are they to replace on the side of the road somewhere?

 

If you have a D2 then you have a Bosch engine and none of this applies to you.
And no I do not know how hard they are to replace.

 

I’m so embarrassed, it turns out that it was corrosion on the Positive (+) wire going into the battery terminal. Once I cleaned it up it started no problem. Oh well at least I got to learn all about the alarm & starting systems. Mark G, you are the man!!

 

Goes to show you that 90% of the time it is the simple overlooked stuff that causes problems.

 

Most people learn the hard way (I know I do), now it won't happen again. Thanks for the update. Battery clamps and cable ends are one of those things that should just be replaced every 10 years or so, usually you can't see the corrosion at all.

 

Glad you got it going! Ha, Ha... the reason I know about combing through the basics firstis because I've made the mistake numerous times over the years overthinking a problem only to later discover the problem was the result of the small or obvious (that I was overlooking).