2002 Cadillac Deville P0410 Code: Secondary Air Pump Not Running After Replacement
I'm experiencing a recurring P0410 fault code on my 2002 Cadillac Deville. I've already replaced the relay and the secondary air pump, and the code resets after about 30 miles. Two questions: First, when I opened the fuse box in the engine compartment, I found a slot labeled 'Air Pump 50a' with no fuse installed—does this mean it's powered directly by the vehicle's electrical system or is there a missing fuse? Second, a mechanic used a handheld diagnostic device and pressed buttons to test the pump, stating that it wasn't running. This prompted my replacement of both the air pump and its hose. However, I'm unsure how to verify whether the secondary air pump is actually operating—what's the correct way to confirm this without specialized tools?
A professional OBD2 scanner can command the air pump to run during diagnostics, allowing direct verification of operation. With an official wiring diagram, you could perform a relay bypass test to isolate power issues. Use a digital multimeter (DVOM) to check for voltage and continuity in the circuit while the engine is running to confirm proper signal flow.