shall not be liable in an action brought against the employer for a violation of section 6(d) if— (A) during the period beginning on the date that is 3 years before the date on which the action is brought and ending on the date that is 1 day before the date on which the action is brought, such employer completes a job and wage analysis audit to determine whether there are differentials in wage rates among such employees that may violate section 6(d)