Rick's Free Auto Repair Advice

Posts Tagged: overheating

Engine Overheats – GM vehicles

Engine Overheats No radiator fans on GM vehicles, Chevrolet, Impala, Pontiac, Buick, Cadillac GM uses a pretty nifty technique to control the radiator fans on late model vehicles. The system consists of two fans and three relays. When the powertrain control module (PCM) detects the need for cooling from the engine coolant temperature sensor (ECT) at 223 degrees or refrigerant pressure above 190-psi., it provides a ground signal to the low speed fan relay. Power flows to one fan, and the ground for that fan flows to the second fan. … Read More

Car overheats – Chrysler Vehicles

Car overheats – Chrysler products People always ask why their Chrysler car overheats. Aside from the mechanical reasons explained here, Chrysler products rely on a solid state radiator fan relay that can cause problems. The relay is usually mounted in the front of the vehicle on a frame rail. That’s great for cooling the relay, but it also exposes it to lots of water and salt. Since the relay is solid state and provides almost 40-amps to the radiator cooling fans, it can get quite hot. The frame rail is … Read More

P1489 and overheating 300M

 Fix code P1489 and overheating 300M Owners who have an P1489 and overheating 300M with trouble code  High Speed Fan CTRL Relay Circuit, here’s what to do. Remove the high speed fan relay and use a digital multimeter to check for power on the two terminals of the electrical connector. If you show power, reinstall the relay. Then ground the dark blue/light green wire at pin 69 of the PCM. The relay should click. If it doesn’t try swapping in a new relay or run a continuity test on the … Read More

P0480 Cobalt Fix

Fix code P0480 on Cobalt This vehicle has a 2-speed cooling fan. If you run into the P0480 code and find that the fan will only run on the highest speed, start by checking for a blown cooling fan fuse #1 in the underhood fuse block. If that’s ok, swap cooling fan relay #1 with the high speed cooling fan relay #2. Both relays have the same part number. Rest the PCM to clear the trouble code and drive the vehicle. If the low speed relay is bad, the swap … Read More


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