Nissan Repair: 06 Pathfinder 2.5 diesel, alternator pulley, smooth roads

Question
Hello,
2006 Pathfinder LE with only 30K miles.  Touring when whine heard.  Soon after the alternator pulley detached but was retrieved and refitted by AA patrol who trimmed the damaged belt to get us home.  Immediately after this incident the LED display for climate/AC, temp, status etc, began to flash off and on intermittently and with it the fan stopped and started.  The display and fan were sometimes normal on rough roads and very erratic on smooth roads so it's not affected by bumping.  Just had the belt replaced by Nissan agents who were unable to find the fault.  They want the vehicle back for two or three days next week to investigate. The fault continued unaffected by the new belt but by the time I had driven the 30 miles home, the whine which preceded the pulley becoming detached has returned.  I can't see anything wrong with the belt or pulley with the engine stopped and running. I am apprehensive about leaving the vehicle with the main agents for two or three days when they admit they have no theories as to the cause of the problem. The 'flashing' display problem must be connected with the pulley incident or the re-fitting of the belt.  The vehicle was absolutely trouble free and has been serviced meticulously by the main agents since they supplied it. They did check to see if damage to the loom was apparent but found none.  Could the fault be the alternator itself?  I am at a complete loss to understand the fault and any suggestions you have will be very welcome.  Many thanks.  Peter

Answer
Peter,

I agree with you that the alternator is the most probable culprit.  I would have the shop perform an electrical inspection to verify the alternator is working correctly.  If voltage output is below normal it will cause the climate control and other electrical items in the vehicle to do strange things.  You could remove the belt and turn the pulley by hand.  But, that is not going to provide you with electrical output information.  But, it would confirm that the alternator or its bearings are going out.