Diagnostic Aids
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
To locate an intermittent problem, use scan tool to monitor DTC P0480 LAST TEST with engine running, ECT below 216°F (102°C) and A/C relay commanded off. Wiggling wires while watching for a change from PASSED to FAILED may locate the area where an open or short to ground in the wiring may exist.
Cooling fan relay 1 coil resistance: 60-90 ohms.
The ECM will turn on the cooling fan relay 2 for low cooling fan speed and both cooling fan relay 1 and 2 for high cooling fan speed. This is intended to reduce current surging when going from low to high speeds. Once the ECM has enabled a low or high fan speed, that speed must run for a minimum of 20 seconds.