Chevy Silverado Cooling Fan Relay Location by Model Year

Where the cooling fan relay is on a Silverado

When a Silverado has electric cooling fans, the relays that control them are in the underhood fuse block. That block is usually on the driver side of the engine compartment, near the battery. Open the lid and read the label printed on its underside. It identifies each relay and fuse position, and the cooling fan relays normally carry a fan-related name. Positions and labels vary by year, cab, engine and options. Treat the lid diagram or the owner's manual for your own truck as the authority, not a picture from another model year.

On the 1999 to 2006 body style, including the 2005 and 2006 models, most engines drive the radiator fan mechanically through a clutch, so there is usually no cooling fan relay to find. The 2007 to 2013 trucks largely follow the same pattern. The main exception is the Silverado Hybrid, which uses electric fans. From 2014 through 2018, many light-duty Silverados use electric fans, so for a 2014, 2015, 2016, 2017 or 2018 truck the search usually leads to the underhood fuse block. Heavy-duty versions from those years often still have a clutch-driven fan, so check before assuming a relay is involved.

How the cooling fan circuit works

A relay is an electrically operated switch. A small control current from the engine control module energizes the relay coil, and the relay contacts then carry the much larger current the fan motor needs. The engine computer decides when to run the fans based on coolant temperature, A/C demand and other inputs. A relay that clicks while the fan stays still points to a different fault than a relay that never receives its command. Depending on the configuration, a truck may have more than one fan relay so the fans can run at different speeds. In that case one relay can fail while the fans still work at one speed.

The fan gets its power from the 12-volt starter battery and the alternator through a high-current fuse. Low system voltage from a weak battery, corroded battery terminals or poor charging output can make a fan run slowly or make the relay chatter. Excessive voltage drop across a connector or ground causes the same symptoms. For that reason, measuring voltage at the fan while it is commanded on tells you more than testing the battery alone.

What changes the answer for your truck

The type of fan drive matters most, so look behind the radiator. A large fan mounted on the water pump or a pulley inside a shroud is a mechanical fan with a clutch. Its engagement is controlled by temperature, or by the engine computer through the clutch itself, not by a relay. One or two motor-driven fans mounted on the radiator shroud, each with its own wiring connector, mean an electric system that uses relays.

Engine, duty rating and equipment also change the layout. A 1500 and a 2500HD from the same year may not share a fuse block arrangement, and towing or fleet packages can add circuits. Mid-cycle updates mean a truck built late in a model year can differ from one built early. The 2009 to 2013 Silverado Hybrid has a high-voltage traction battery and orange high-voltage cabling in addition to the ordinary 12-volt battery. The fan relays in the underhood fuse block are on the low-voltage side. Still, never probe, unplug or work near orange cables or hybrid system components unless you have the training and the proper disabling procedure.

How to check the relay and fuse yourself

Start with the engine cold and the key off. Find the fan relay and fan fuse using the lid label, and confirm the installed fuse rating matches that label before you replace anything. Never install a larger fuse to stop one from blowing, because that hides a shorted motor or a chafed wire. A blown fan fuse usually points to the fan motor or wiring, not the relay.

A quick test is to swap the fan relay with an identical relay, same part number, from a non-critical circuit in the same block, if one exists. If the fan then works, replace the relay. With the engine running and the A/C on, or with a scan tool that can command the fans, you can often feel the relay click. You can also measure voltage at the fan connector. Compare it with the voltage at the battery terminals. A large difference under load suggests resistance in the feed or ground circuit rather than a bad relay.

Do not jumper relay socket terminals at random. Terminal layouts differ between relay types, and bridging the wrong pins can bypass a fuse or push voltage into a module circuit. Use the wiring diagram for your truck to identify which terminals carry battery power, which feed the fan and which are switched by the engine computer. If the fans keep running with the key off, a stuck relay can drain the battery. That kind of parasitic draw shows up as a dead battery after the truck sits. Pulling the relay is a reasonable temporary step while you diagnose the cause, but watch engine temperature closely when you drive.

Limitations and when to get help

Model-year rules of thumb are only a starting point. Fuse block labels, relay positions and fan control strategies changed between generations and sometimes within a single year. Confirm your truck's engine and fan type, and use the diagram on its own fuse block lid. If your Silverado has a clutch-driven fan, overheating diagnosis moves to the fan clutch, coolant level, thermostat, water pump and airflow through the radiator, not a relay.

Get professional help in any of these situations: the engine is overheating, the fan fuse keeps blowing, the computer is not commanding the fans, a fan-related trouble code is stored, or the truck is a hybrid. A shop with a factory-level wiring diagram and a capable scan tool can command each fan circuit and find the fault quickly. That usually costs less than replacing relays and fans by trial and error.