Volvo Repair: Reset Check Engine Light, volvo 850 glt, smog test

Question
Is there an undocumented way to reset the Check Engine light on my Volvo 850 GLT?

I have a 1993 Volvo 850 GLT.  My radiator failed last summer and I had my non-Volvo certified mechanic replace it.  The Check Engine light has been on ever since.  I've simply ignored it until now when I failed my smog test only because the Check Engine light is on.  I haven't been able to find an inexpensive way to reset it, and all the dealers want ~$125+ to scan the codes and reset the light.  I know that there is an OBD tool that costs ~$100, but I intend to sell this car in the next year and can't see spending that much money on a tool for one use.

Is there an undocumented way to reset the Check Engine light on my Volvo 850 GLT?

Answer
Brandon, yes there is.  Since its a 93, you can manually read the codes and clear the light.  Where the washer bottle neck is, there are 2 small black boxes.  Open #A and put the connector in #2.   Turn key on and hold button for 10 seconds.  Read codes.  Example 1-2-1, etc.  after the 3rd flash, hit the button again.  If the same codes flashes, then hold the button for 5 or so seconds until the light is steady.  Now hold for 10 seconds.  Light should clear.  you must read all the codes before it will clear.  Do this on number 6 also.  Roger