Diagnostic Aids

Inspect the wiring for poor electrical connection at the PCM. Look for possible bent, backed out, deformed or damaged terminals. Check for weak terminal tension as well. Also check for a chafed wire that could short to bare metal or other wiring. Inspect for a broken wire inside the insulation.
When diagnosing for a possible intermittent short or open condition, move the wiring harness while observing test equipment for a change.
Check customer driving habits and/or unusual traffic conditions (i.e. stop and go, expressway).
Check brake switch for proper mounting and adjustment.