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Home >> Chevrolet >> 2001 >> Impala Base, 3.8 K >> Repair and Diagnosis >> External Pages >> Different car >> Section 36 (HVAC Systems - Automatic) >> Diagnostic Tests >> DTC P1546: A/C Relay Circuit Malfunction >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue. However, it is still accessible from the selected car via links, so may be relevant.

Battery positive voltage is supplied to the A/C compressor clutch relay. The Powertrain Control Module (PCM) controls the relay by grounding the control circuit through an internal solid state device called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be near zero volts. When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be near battery voltage. If the fault detection circuit senses a voltage other than what is expected, this DTC will set.