S13 Wiring Problem: Check Engine Light

[Explodicide]

I've got an S13 '89 (probably an auto to start with) that had an S13-version manual KA24DE swapped in (I didn't do it, I bought it this way.) I'm pretty sure that it's a '91 ECU because it's got the green number 24 on the side of the case.

The CEL is, for some RETARDED reason, not hooked up. I've found the wire coming out of the cluster, and the bulb still works if I connect it to ground, but it wasn't connected to anything. (PS, I'm in Cali, so I NEED to get this thing hooked up so I can pass smog)

I've found the diagram in the '91 FSM that shows where the CEL is connected into the harness (pin 24. EC pg. 9, if anyone was wondering. took me a bit to find) The color of the wire in pin 24 out of the ECU matches the harness, but when I connect them, the CEL does nothing.

Testing that wire with a multitester shows that it does not go to ground at any point (which is what the light needs to go on.) I'm completely stumped. Any ideas?

TIA.