Hi, have a 01 chev suburban. Check eng. light came on. Went to 2 different places and both could not get codes. Scanners should turn on with ign. and they will not. Screen stays blank. There is power to the OBD2 16 pin outlet port under dash, I believe on the bottom right. Also tried a friends new code reader which works perfect on my other truck but will not turn on with suburban. Any ideas? Thanks