Late reply, but I'm adding this mostly for others finding this via search engines.
I had exactly the same symptoms and same AHT error code with a machine of this model (A1278 i7 2.7) that experienced some water damage (the only other problem caused by this was the death of the SSD). I've been able to temporarily work around it by unplugging the AirPort card (it's the one running from the logic board to the board with the three small round gold antenna connectors).
If you're going to try this, unplug it at the logic board end, and tuck the free end of the cable with the connector behind the logic board so that it doesn't just re-mate with the logic board connector when you put the back case on again.
I'll update here when I've replaced the AirPort card.