I have a1989 iroc z convertible and am having trouble reading codes. If I jump a wire between the two connectors on the diag plug I get my code 12's like usual but I used a older auto X-ray scanner that I used in my 86 and worked fine but this car says communication error. So I got a new solus ultra scanner to read the info and that two also says communication error. Both scanners work fine except on this car. Does anyone know what might be the problem. I pulled the connector down and checked the wires and they seem fine. Just wondering if anyone else has had this issue. Thanks

 

This is actually common on the '7165 ECMs. Being an IROC I am assuming it is TPI...

If you have an ALDL cable can download (free) WinALDL and try it. It runs at the slower 160 baud but if it connects you are good to go.

RBob.

 

Ya it's a tpi. Well this sux just bought a snap on solus ultra well at least it has many other uses I need it for.