DTC P1546: A/C Clutch Relay Control Circuit: Description

Ignition voltage is supplied directly to the A/C compressor clutch relay. The PCM controls the relay by grounding the control circuit via an internal solid state device called a driver. The primary function of the driver is to supply ground for the component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage of the control circuit should be near zero volts. When PCM is commanding the control circuit to a component off, voltage potential of circuit should be near battery voltage. If fault detection circuit senses a voltage other than what is expected, DTC will set.