Originally Posted by
steve_o
igntion on they both turn live, when cranked one pulses live and the other pin stays live
This exactly what you should be getting.
The reason both pins have 12 volt with ignition on is the following:
1 pin is the feed, it always has 12 volt on it. The other is switched by the ecu.
To define the signal and minimize noise a pull-up resistor to 12 volt is used.
When 1 pin pulses during cranking fuel is injected.
Try starting with a disconnected catalyst. Will make a lot of noise!