The purpose of this test is to compare the duty cycle signal of the VVTi control actuators against manufacturers specifications.
The solenoid has two terminals, both may have supply voltage at ignition on.
The switching frequency is dependent on engine system variations at the time of testing, EGR function, temperature, RPM etc. The switching frequency and duration will also vary with different vehicle manufacturers.
The Variable Camshaft Timing (VCT) solenoid is an actuator. It is commonly supplied with an ignition live and a ground provided by the ECM. Note that either the positive or the ground duty cycle can change depending on the design of the system by the OEM.
You can compare the duty cycles of both actuators with each other and against manufacturer's information, but you may need to load the engine to make the duty cycle of the exhaust actuator change with engine operating parameters and EGR conditions.
The use of VCT has become widespread throughout the automotive industry as the technology becomes cheaper and more manufacturers take advantage of it.
Variable camshaft timing is used to increase engine torque in the low engine speed range and to increase power in the high engine speed range. The use of VCT means that we can control the closing and opening times of inlet and exhaust valves. As a result VCT may also be used in place of an EGR (exhaust gas recirculation) valve.
Should you suspect a fault with the signal, test the wiring from the Powertrain Control Module (PCM) to the VCT actuator.
Ensure that the PCM has good power supplies and grounds where required or specified.
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