Iron check only works with ID Norm set to off. The principle is that while most non-ferrous target IDs will shift higher or lower with increasing or deceasing operating frequency, ferrous target ID stays relatively constant independent of frequency even if it falses into the overlap region (97 - 99 ID) or if you are getting high target ID due to a mixed ferrous/non-ferrous crown cap. So the iron check merely is a way to take your favorite program and simply change the operating frequency to 4 khz. That way if you have a suspected ferrous target that is giving you a high tone, you can switch to the iron chk program quickly using the plus-minus buttons and check for a target ID shift down at 4 khz. If target ID stays the same or goes up, then you have a probable ferrous target. You still can't be 100% sure unless you dig it. Since it works with any base program, I don't provide explicit settings for it.