!. Check for Diagnostic Trouble Codes with a good scanner. You need to get deep into the various system. Generic DTC's may not be enough.
2. Check in the rear, under the foam for water near the air pump
3. Look at the connection piece that mates onto the BCM for bent pins/contacts or area of burn. That may help you isolate the problem to a particular circuit.
4. Get a copy of the service manual ( avalible from this web site) to help with wire ID
5. check for burned/arced fuses in the under hood fuse box.

GOOD LUCK