Coolant fan 1 controller???

I'm new to the forum and am sorry to start with a question, but my mechanic seems a little lost. I'm getting a DTC of p0480 which is coolant fan 1 controller. Does anyone know what this means? Is it the computer, temperature sensor, or other. The coolant fan doesn't come on. No fuses are blown, the fan can be hot wired and will run, and it has new fan relays. Thanks for any help.

DTC P0480 or P0481
Cooling Fan Relay Control Circuit

the only part of the cooling fan circuit the PCM can 'see' or detect is the wiring and the relay. swap the two cooling fan relays. if the code becomes P0481 (fan #2) the relay is bad, if it stays P0480, it may be the wiring.

Thanks for the reply. I've put in 2 new relays and have tried switching them around and still the same code. It's on a 03 RDV with 70K miles that I just purchased. I talked to the previous owner and she never had a SES light. It seems to have started after the dealership detailed the engine. Maybe just coincidental or they knocked off a wire or shorted out something. I unplugged the engine coolant temp sensor trying to trick the fan on, but no luck. The second fan comes on when the a/c is on. Any ideas?

get a ohm meter, test all four relays, use the orginal fan 2 relay as a guide. then test the voltage drop of the relays while in the fuse box.(voltage drop, i tryed measuring available voltage and i got a false reading)

I took it to my local mechanic. He didn't have the computer needed to run diagnostics. So I took it to a GM garage. They've ordered a new PCM. Good news is, they said it was covered under warranty up to 80k miles. I thought warranty had long since run out. Hopefully that will fix the problem. My first mechanic said that would be the last thing to try, after checking all the wiring. I hope they checked the wiring well. I'll know Friday when they put the new PCM in.