how do i wire in a "check engine" lamp?

[the toecutter]

did a bit of research here and elsewhere, poked through the wiring diagrams and can't quite come up with the right answer.

1994 SC400 engine/ecu/trans into a '94 hilux. i'm having an intermittent hesitation upon acceleration problem, but alas no lamp to indicate a code for me.

pretty sure i schmutzed up the maf somehow, the air intake plumbing was the last thing i messed with before this cropped up.

 

[gloverman]

http://www.lextreme.com/forums/showthread.php?t=14972

 

[the toecutter]

thanks. i sorted out where it was on the ecu (plug "A" pin 6, blue wire with yellow stripe) but it doesn't seem to work, nothing at the engine obd plug either. if i'm reading the wiring diagram correctly, it's a ground switch. but no ground when the key is switched to the "on" position. test lamp from power to ecu, nothing. is my ecu the problem perhaps?