My 2003 automatic has started to overheat badly idling in traffic in hot (about 85-90 deg F.) weather. Fluids and lubricants are OK. Checking the fan circuit, all 3 relays are OK as are the fuses. If I short between the outputs contacts of fan relay 1 both fans come on at low rpms, if I short between the outputs contacts of fan relay 2, 1 fan comes on at high rpms. Normal? My chiltons manual doesn't even show the 3rd ralay, "fan mode, which like the others is a spst so I don't think it can be used to select either fan relay, any ideas as to what it does?