Volvo Repair: Engine shuts off, flash flash flash, black boxes

Question
My son's '94 850turbo has been shutting off on him.  It has happened several times while he stopped at a light or at a stop sign.  It seems as if it is idling rough.  Is there a way to adjust the idle on his car?

Thanks!!!

Answer
there is no way to adjust the idle it is computer controlled.you could try checking for diagnostic trouble codes.




behind the passengers side head light are 2 small black boxes,1 marked A ,and 1 marked B.on box A there is a small wire insert the wire into the hole marked 2 then turn the ignition key to position 2 but not started.then on the box narked A push the small button for 1 second then release it.the small red light will flash a code back as a 3 digit number.there is a short pause between flashes for a single digit and long pause between the different numbers.example:
a 121 would look like this flash.....flash..flash....flash
write down each code,then after the first code repeats its self then press the button for 5 seconds the light will light when pressing button then go out when released,then the light will light steady again when it does press button fo 5 seconds again,this should have reset the check engine light.let me know the codes. i will tell what they refer to.
         Rege