I use the pin in the wire, to check signals. Sometimes you can poke the probe in the back of the plug. But if you are going to use it on the road, I would poke a pin through the wire,and use an alligator clip around the wire and pin, to hold it solid.
When you go to measure the signal, use a DC setting first, if it just stays the same, it is a pulsed signal. To read this signal, use a frequence setting to see the frequence change. If you don't have frequence setting, use AC.
As this signal is from the crank sensor, through the ECU, it is most likely a pulse that the TCU counts, to limit the maximun gear change. The box does not use this signal for normal changes, it uses road speed and throttle opening to change. As far as I know it is only used for the change when the gear lever is in any other posiion other than D.
If it is a pulsed signal, you may be able to turn it off, when you are changing gear with the lever.
Harvey.
