This reading should remain across the range until the full load setting is reached, when the signal should switch back to zero again Frank warns that working on this engine requires plenty of 'deep' work around the inlet manifold. Access can be limited so working with a cool engine will help avoid too many burns etc. A breakout box used between the ECU and the harness, or back-probing then the main ECU socket, provides a more convenient approach. In the worst case when the engine will not run check the basics first. Pin 1 at the ECU will really have to be checked using an oscilloscope because the trigger signal is a square wave.
Frequency varies with engine speed so is inconsequential.
The shape of the switch must be assessed. Erratic or non-existent coil switching are terminal problems for the module. No repairs are possible so a new unit will be needed. Genuine replacements from Bosch cost about 120 according to Frank. Other makes are available for considerably less but quality is reduced.