1993 Sierra: How to read dtc codes?

[redbul]

Dear all,

I have a a Tech2 with a GM datacard up to 2009. I use it on my '08 Corvette with another connector.

I have problems in using this Tech2 on a '93 Sierra.

When I plug in my Tech2 I cannot power it up, so I use external power supply to start up my Tech 2.

When my Tech 2 powers up, I surf through the menu's to get to the dtc codes. but then I get the message 'No data communication': ignition on or off makes no difference.

What do I do wrong?
Is there a special procedure to follow to read the dtc codes using Tech2 on this Car?

Thanks a lot for any help, Jan

 

[kobrak]

Are you sure your 93

is true OBDII? Might it be OBD 1 1/2? I can't remember off hand. As a gut check, run over to advanced for a free scan just to make sure there isn't a problem with the connector itself?