Gahh, another help me thread

So my auto trans has been doing funny stuff latley (randomly droping out of gear at low speed) and I got ahold of the BTR service manual and there are error codes that can be read from the ECU

So, made up an LED test light and jumper, and rigged it up according to the instructions and nothing! LED comes on as soon as its pluged in and goes out as soon as I flick it onto ignition.

Any ideas?

Thanks