You're right to look for a short to ground in that circuit. I'd disconnect the elec connector from the EEC and ohm out the SPOUT circuit (EEC to SP-in at the TFI). Look for way less than 5 ohms of resistance (I'd want near 1 ohm).
Also ohm out the wire itself (checking continuity to ground, in case there's a short). You should see a ton of resistance.