I have an 02 LS1 into my 1995 BMW M3. I went to tune get the car tuned and they had problems linking up to the OBD2 port becuase there was no power to it. So I took the car back home and checked the wiring.

I found it was not wired correctly so I cut all the wires and started fresh.

-connected Pin 16 of the OBD2 port to a constant 12v
- tapped (soldered) pin 2 of the OBD2 port to the back of the PCM at Pin 58 (dark green)
- Connected pin 4 and 5 together and grounded them

Now when I plug the scanner in it gets power but when I press read, it says "No Link"

What could be wrong? Please help

 

Are you trying it with the ignition switch on? Even though you are powering the scanner with the OBD port, you still have to have the switch on to read the pcm.

 

Yes, I am trying it with the ignition switch on. The car even starts and runs. Is the green wire needed for anything else besides the serial port? Maybe because I just tapped it in that its signal is getting disturbed by whatever else its connected to?

 

There should be constant power on pin 16 of the OBD2 port and also ground on pins 4 and 5. if you have these connected this way there will be power at the diagnostic port.

 

Thanks guys, got it to work. I was pressing scan too fast when I turned the car on.