Problems getting ECU codes

[dynmicracr]

I have a 91 Sy and it has a check engine light. I cant get the Check Engine light to flash when I ground the A and B connectors (two in the top right). I have tried it with the ignition in the on position and then grounding it, and also have tried grounding it and then turning it to the on position. Are there any tricks to doing it on a Sy? I have done it on my Supra flawlessly.

I bought it the Sy off of my Father in Law and it has some piggy back unit with a key in the glove box for switching maps. Could this be keeping me from getting the codes? I would assume not.

Thanks for the help...

Alex

 

[dynmicracr]

After tinkering with it a bit more I decided to erase the codes. After pulling the positive terminal the codes were still there. At least the check engine light was on still. So I pulled the DIN plug from the external EPROM box and plugged it back in. After that the ECU flashed only 12 for diagnostic mode. Once I pulled the jumper out the CEL went out. I have a feeling that when my friend was in the passenger seat, he knocked the plug on the EPROM box or something. BTW the key in the glove box has PROMPAQ written on it. Probably a bit old school but gets the job done.

Alex