I'm working on a project with a vehicle using two engine control modules, which both need accurate crankshaft position signals to function. Adding a second sensor is not an option. The sensor is an inductive sensor producing a semi-sinusoidal waveform, NOT a Hall-Effect sensor.
The issue I have been seeing and have tested is that as the frequency of the inductor is increasing, i.e the vehicle RPM is increasing, the voltage applied to one of the modules is leveling off. I measured the sensor to produce a voltage of around 12VAC at ~7000rpm, however when split one of the connections measured at only 4VAC. The frequency measurements were correct for both computers, however I believe that they also use the applied voltage to determine engine speed.
I do not have any technical documentation for this sensor, as it hasn't been made public to my knowledge.
What are some possible solutions for this problem? I have considered using an opamp but am unsure how that would improve the situation.