The problem, I now realize, started about a year ago.  (Our car is a 1991 turbo 940 volvo station wagon) Periodically when the car is started instead of all the lights on the panel lighting up for a quick second only one light, usually the 4th gear disengagement arrow, comes on and stays on for some time as we start driving.  The amount of time the light stays on varies.  Three times in the last 6 months, the car has "died" while we were driving.  While not sure about the circumstance the first two times, certainly the last time it was when only the arrow light went on when the car was started.  When the car died all the systems faded out  - the radio faded out, the panel lights dimmed and went out, etc.  When I tried the ignition nothing happened.  The first and third times the car died we needed to get a tow but the second time it died just as we were pulling into our driveway.  After sitting for three days we were able to start the car and take it to the garage.

The garage has tried to resolve the problem 4 times.  We have at least three AVR test and battery charges.  The garage has installed a new voltage regulator brush kit, a 100 A alternator and anew ? voltage regulator.  Once they fixed a corroded connection and last week they dealt with a loose connection they found when they took off the dash.  But still the problem persists.  This weekend about 50% if the time I started the car the arrow light came on instead of the entire panel of lights. 
 
Any suggestions or advice would be appreciated.