how much does it cost to get a diagnostic for a 95 850 turbo automatic?

Question

Those computers that tell you why the check engine light is on? How much ?

Answer 1

If you just need it once, bring it to a parts store like Pep Boys or Autozone. They can run a scan on it once for free, in the hopes that you'll buy the parts to fix it from them.

As for the tool, here's one example for sale that should work:

http://www.autozone.com/servlet/UiBroker?UseCase=C001&UserAction=performMoreDetail&Parameters=TRUE%7C%7EScanners+%26+Testers%7C%7ENONE%7C%7EActron++++++++++++++++++++++++++++++Super+Autoscanner+OBD+I+%26+II%7C%7ENONE%7C%7EFALSE%7C%7EFALSE%7C%7E431997%7C%7E91%7C%7ECP9145%7C%7EOBD+II+Ready+And+OBD+I+With+Optional+Accessory+Cables%7C%7E%24279.99%7C%7ENONE%7C%7ENONE%7C%7ENONE%7C%7ENONE%7C%7E3.8%7C%7ENONE%7C%7EB%7C%7EACM%7C%7Etrue