[88 Beater]

This forum is great. I found the wiring diagram in the FAQ and it seems to be more correct than the ones in the Haynes manual. The Chilton's manual doesn't even show the SES circuit.

Anyway, it's a very simple circuit that goes from the ECM to both the SES light and ALDL terminal D. I unhooked the battery and ECM, then using a 9v battery I hooked + to pin A5 and - to pin A12 on the ECM connector - the bulb lights. I also hooked + to ALDL terminal D and - to terminal A and again the SES bulb lights. Starting to look like the ECM is fried I guess.

There is something strange I'm not sure how to interpret though. I hooked the ECM and battery up again. Now that I know I can hook a voltmeter up to the ALDL and see what's going to the SES light, I did that and turned the key on. I get about 10.5 volts that stays on. Next, I tried jumping ALDL A/B with the meter still hooked up. When I turn the key on, I get the needle barely twitching up to about 11 volts in the 1-2 pattern. No other codes (and bulb still doesn't light). Before, when I was checking with the meter in the bulb socket, the meter acted just like the light should. It showed voltage for about a second then went to zero when I turned the key on. With the ALDL jumped, the needle swept up from 0 in the 1-2 pattern.

I guess maybe all this weirdness is typical for a fried ECM but since it's brand new (well reman - but a Delco reman), I guess I probably have something shorted that's causing the ECM to burn up? Not sure why the ECM fuse wouldn't blow if that's the case though. Maybe I'll open up the ECM and check for solder bridges or bad solder joints just for fun.