fiat 3 pin red lead
Posted: 31 Dec 2014, 16:35
hi can you tell me what the red lead is for on the 3 pin connector
To provide a power feed to the Elm3270 device from the vehicle.
With vehicle diagnostic interfaces there is a requirement to provide isolation between the power systems of the vehicle and the testing equipment. This means that the interface has to be powered by the vehicle and via the PC/tester.
In some/many/most/ earlier Fiat/other diagnostic test sockets there is no 12V supply so when you connect your ELM/other interface there is no power to it.
Suggest you do the following:
1) connect 3 pin socket ONLY and leave the PC/USB lead unplugged. Most decent ELM/other interfaces have a power led that indicates that the interface is receiving power from the vehicle. If this light indicates power then connect interface to PC/USB and see if you can connect to the vehicle.
2) if 1) fails then connect the red lead to the car's +12V battery terminal and try again
Nick