XG350warning light problem
 

Here is a stumper for Hyundaitech.

2002 XG350 with 36000 miles. Chicago, IL area. 20 degrees F this
morning. 40 degrees F now. Driving home yesterday in the cold and dark
with lights on including fog lights, heater, heated seat, radio and
wipers intermittent.
Battery icon and brakes icon both glowed briefly then went out. Did
not reappear for the remainder of drive home.

Started car and drove to work this morning. Headlights were on auto
and never went out by themselves even though it appeared to be plenty
light enough to automatically turn them off. Lights, heater, radio,
heated seat all on. After 20 minutes of driving while stopped at stop
sign upon accelerating from stop the battery icon, brakes icon, ABS
icon and TCS icons all lit and stayed lit. I drove to Hyundai but they
were on holiday hours and unable to assist. The service manager
guessed at an alternator?

No Hyundai locations are able to assist until after the holiday so I
took a chance and drove it home after finishing work. Upon starting
the car up no icons were lit and the car drove normally. Everything
seemed to work fine. I tried to get it to do it again by turning
everything on including the rear window defogger. After several
minutes of this while driving the same icons as before lit, battery
icon, brakes icon, ABS icon and TCS icon. Once they lit I noticed the
rear window defogger was no longer lit. I also noticed the speedometer
was locked at about 10mph and would not move, the tach worked
normally. Upon pressing the rear defogger switch it would not work (no
light on the switch). I turned everything unneeded off (headlights,
heated seat, radio) and drove home. All icons stayed lit until all the
way home. Once in the garage I popped the hood and checked the voltage
at the battery, which read well over 17 volts. Upon turning on the
headlights it dropped to about 14.5 volts. Once the car was stopped
and in park I noticed the ABD and TCS icons were no longer lit.

Any ideas? It sounds to me like the alternator but the voltage outputs
actually seem high.