P1546 Chevrolet -

Question

P1546 code. Have power to a/c relay. a/c works if relay ground wire is ground to battery-. ECM not grounding relay when a/c on switch is pushed. Same in defrost mode. Chev dealer not able to find solution after charging for diagnostics

Answer 1

P1546 A/C compressor relay

The ECM is what gives ground to the A /C compressor, You need to measure the voltage loss at the ECM loss is, This will determine if the ECM is at fault, other than that swap out the A/C relay with a differnt relay.If it works replace the relay.