PLT OF C172 CONTINUES PRACTICE ILS APCH DESPITE DIFFICULTY IN GETTING AN APPROPRIATE HSI DISPLAY DUE TO NOT SWITCHING FROM GPS TO RADIO MODE.

Narrative

I WAS ON RADAR VECTORS FOR THE ILS RWY 25 APCH AT MQJ AND WAS CLRED FOR THE APCH. I WAS NOT GETTING A READING ON THE HSI FOR THE LOCALIZER BECAUSE I HAD NOT SWITCHED IT OVER TO NAV FROM GPS. I WAS OVER THE OUTER MARKER SO I DSNDED TO VFR. STILL CONFUSED AS TO WHY I HAD NOT PICKED UP THE LOC; I TUNED NAV 2 INTO THE ILS. THIS SHOWED FULL SCALE DEFLECTION TO THE R OF COURSE; WHICH CONFIRMED MY POSITION (THE HSI ON GPS INDICATED I WAS TO THE L OF COURSE). AS I WAS IN VFR; I CONTINUED VISUALLY TO THE ARPT; EXECUTED A MISS AND CONTINUED MY FLT. AS I WAS ON THE ILS I SHOULD HAVE GONE MISSED AS SOON AS I REALIZED I WAS FULL DEFLECTION. THE REASON FOR THIS ERROR WAS PRIMARILY THE FACT THAT I HAD NOT FLOWN IN IMC FOR FOUR MONTHS. THIS LED TO A ROOKIE MISTAKE IN NOT PUTTING NAV INPUT INTO THE HSI. ALSO; MY LACK OF RECENT EXPERIENCE AND A DESIRE TO NOT LOOK BAD IN FRONT OF THE CTLRS LED ME TO CONTINUE VISUALLY TO THE ARPT RATHER THAN IMMEDIATELY EXECUTING A MISSED APCH AFTER I HAD DISCOVERED MY ERROR.