95 blazer, OBD-II scantools not reading

This is the #^@#@%@ CPI engine. Nice HP, but that's it.
It is supposed to be OBD-II compliant, but have wasted money on two different scantools (Stinger and a PC-interface), and neither can read codes (stinger can erase codes).
GM dealer COULD READ IT, so my onboard interface is working.

HINTS? IDEAS?

Thanks.

Dave.-

Some times the computer can messup and you need to change it just to read the codes
ki4byz

Some(actually quite a few) OBD2 scanners cannot read some 94-95 GM's because they are not fully OBD2 compliant. My Auto Xray scanner has a separate cable just for these vehicles, the pin assignment is what I think is different

If you have a real scan tool, and not a code puller,set the scanner to 96 generic OBD2. I have run into this many times,you probably have the OBD2 plug with the OBD1 electronics.

u have the infamous obd1.5....

my '95 S-10 w/CPI is the same way, and my AutoXray scanner has a cable made just for it.

right tool, right cable, is what you need.