Chevy Tahoe Cooling Fan Relay Location by Model Year
If the cooling fans on a 2015, 2016 or 2017 Chevy Tahoe stop running, the relay is one of the first parts to check. All three model years belong to the same generation, and on all of them the fan relays and their fuses are in the underhood fuse block, not inside the cabin. This guide covers where to look, how the circuit works, and how to confirm the relay is actually the problem before you replace anything.
Where the fan relay sits on 2015–2017 Tahoes
Start at the underhood fuse block. It is the black box with a removable cover on the driver's side of the engine compartment, next to the battery. Release the cover latches and turn the lid over. The underside has a label that identifies each fuse and relay cavity. Look for entries marked for the cooling fan or fan relay. Depending on equipment, there may be more than one fan-related relay and more than one fuse, because GM commonly uses separate circuits for low-speed and high-speed fan operation.
The general location is the same on 2015, 2016 and 2017 trucks. Cavity numbers and relay assignments can still vary with build content. Treat the label on your own lid, or the fuse chart in your owner's manual, as the final authority, rather than a photo taken from another truck. If neither one lists a fan relay, read the section on configurations below, because your fans may be controlled another way.
How the fan relay circuit works
The engine control module decides when the fans run. It monitors coolant temperature and, when the air conditioning is on, refrigerant pressure. It may also use other inputs, such as transmission temperature or vehicle speed. When cooling is needed, the module completes the control side of the relay, which energizes a small coil. The coil pulls a set of contacts closed on the load side, and battery current then flows through a fused feed to the fan motor.
This split between control side and load side matters for diagnosis. The control side carries very little current, while the load side carries the heavy fan current. A relay can therefore click normally and still fail to pass power if its contacts are burned. Corroded connections in the fan circuit can also cause excessive voltage drop. The fan then receives less than full system voltage and runs slowly or not at all, even though the fuse and relay look fine.
What changes the answer
Equipment level is the main variable. Trucks with heavier cooling packages, trailering equipment or special service builds may use different fan hardware or additional relays, which changes which cavities are filled. Some fan systems use an electronic control module that sets fan speed itself. On those, there may be no plug-in relay to swap, and testing focuses on the module and its wiring instead. A wiring diagram matched to your VIN shows which design your Tahoe uses.
Operating conditions change what you should expect to see. The fans do not run all the time. With a cold engine and the air conditioning off, a stationary fan is normal. A fair real-world test is to turn on the A/C, or to let the engine reach full operating temperature at idle. Also note that there was no hybrid Tahoe in 2015–2017. The fan circuit runs entirely on the conventional 12-volt starter battery system, and there are no high-voltage traction components to isolate. The earlier Tahoe Hybrid used a separate high-voltage system with its own procedures, and those procedures do not apply to these years.
How to check the relay yourself
Before reaching near the fans, switch the ignition off and keep hands, tools and clothing clear of the blades, because electric fans can start without warning while the system is powered. For any work beyond pulling a relay, disconnect the negative cable at the battery terminals to remove power from the circuit. Check the fan fuses first. A blown fuse points to a shorted fan motor or damaged wiring. Replace it only with a fuse of the same rating, and watch whether it blows again.
To test the relay, swap it with an identical relay from a nonessential circuit in the same box, matching the part number printed on top. If the fans start working, the original relay was bad. You can also use a test light or multimeter. Confirm battery voltage at the relay's power feed terminal. Then, with the fans commanded on, confirm the control signal on the coil side. A scan tool that can command the fans makes this much quicker. If voltage reaches the fan connector but the motor does not turn, the fan motor itself is the likely fault.
Keep the wider electrical system in mind. A weak battery or low charging output can make the fans run slowly and can set confusing codes, so confirm that the battery is healthy and the alternator is charging before blaming the relay. Some fans may run for a short time after shutdown. If a fan runs for well beyond a few minutes and drains the battery, a stuck relay can be the cause of that parasitic draw. Pulling the relay and seeing the drain stop confirms it.
Limits and when to get help
Fuse box layouts can change within a model year, and replacement fuse block covers are not always labeled for the exact build. If the lid label does not match what is in the box, treat that as a warning sign. If the relay tests good, the fuses are intact and the fans still do not run, the fault is usually in the wiring, a connector, the fan motor, a control module or a temperature sensor input. Tracing it reliably requires the factory wiring diagram for your VIN and a scan tool that reads live data.
Stop and have a technician take over if the engine is overheating, if a replacement fuse blows immediately, or if you find melted connectors or heat damage at the fuse block. Failed fans can overheat the engine quickly in traffic or at idle, so do not rely on highway airflow as a long-term workaround.