Jeep Wrangler Cooling Fan Relay Location by Model Year
If your Wrangler's electric cooling fan stops running, or never shuts off, the relay is a sensible place to start. Where it sits, and whether a separate plug-in relay exists at all, depends on the generation and engine. This guide covers where Jeep places the fan control parts on each Wrangler family, how the circuit works, and how to test it without confusing the 12-volt starter battery with the high-voltage system on hybrid models.
Where the Cooling Fan Relay Sits by Model Year
On the JK Wrangler, built for the 2007 through 2018 model years, fan power is routed through the Totally Integrated Power Module, usually called the TIPM. It is the large black box under the hood on the driver's side, next to the battery. The underside of its cover carries a label identifying each fuse and relay position. Many relays in the JK TIPM are soldered inside the module rather than plugged into sockets, so a relay function may exist without a removable relay you can pull. On a 2014 or 2015 Wrangler with the 3.6-liter V6, the fan feed comes through a fuse in the TIPM, while fan speed is managed by control electronics at the fan assembly on the radiator shroud, based on commands from the engine computer. For those years, do not be surprised if you find no plug-in part labeled as a fan relay.
The JL Wrangler, from 2018 onward, uses an underhood power distribution center near the battery, again with a cover label for the fuse and relay positions. Its electric fan typically has speed control built into the fan module, so the distribution center supplies protected power rather than switching the fan on and off directly. Older TJ and YJ models rely mainly on a belt-driven fan with a viscous clutch, which has no relay at all. Where one of these earlier Wranglers has an electric auxiliary fan, its relay, if fitted, is in the underhood power distribution center, and the cover label is the quickest way to confirm the cavity.
How the Fan Circuit Works
A conventional relay has two sides. The control side is a low-current coil that the engine computer switches, usually by completing the ground path. The load side is a set of heavy contacts that close when the coil is energized, sending battery current through a fuse to the fan motor. The computer decides when to run the fan from inputs such as coolant temperature, air conditioning pressure and vehicle speed. The fuse rating is matched to the wiring and motor current, which is why a fan circuit fuse is noticeably larger than most accessory fuses.
Variable-speed systems work differently. The fan module receives a steady power feed and a control signal from the engine computer, then varies motor speed to match cooling demand. On these setups a fan that will not run may point to the module, its signal wire or its power and ground connections rather than a relay. In every version the fan depends on healthy system voltage. Low charging output, corroded battery terminals or a poor ground can make the fan run slowly or drop out under load.
What Changes the Answer
Model year alone is not always enough. For 2018, the outgoing JK was sold alongside the new JL, so two very different electrical layouts share that year. Check the body style, the vehicle identification number or the build information on the door label before trusting any location guide. Engine choice also matters: the JK used both the 3.8-liter and 3.6-liter V6, and the JL has been offered with several engines, each with its own cooling and wiring details. Aftermarket equipment such as winches, lighting harnesses or replacement fan controllers can reroute power and change what you find under the cover.
The Wrangler 4xe plug-in hybrid adds a high-voltage traction battery and electric drive components, identifiable by their orange cables. It still has a conventional 12-volt battery that powers everyday accessories and control circuits, including the engine cooling fan circuit. The high-voltage components have their own separate thermal management. Fan relay and fuse checks belong only on the 12-volt side, and nothing in the high-voltage system should be opened or probed during this job.
Checking the Fan Circuit Yourself
Start with observation. With the engine warmed up and the air conditioning switched on, the electric fan should run on most models. Watch the temperature gauge, and note whether the fan never starts, runs only at one speed or never stops. Next, find the fan fuse using the cover label and inspect it, or check both sides with a test light. Replace a blown fuse only with one of the same fuse rating; a fuse that blows again signals a short or a seized motor that needs tracing.
If your vehicle has a removable fan relay, swap it with an identical relay from a nonessential circuit, matching the part number printed on the case, and see whether the fault moves. When the fan should be running, measure voltage at the fan connector and compare it with the reading across the battery terminals. Then check voltage drop on both the power and ground sides while the fan is drawing current. A loss of more than a few tenths of a volt points to corrosion, a loose terminal or damaged wiring. A wiring diagram for your exact vehicle tells you which pins carry power, ground and the control signal.
A relay stuck closed or a faulty fan module can keep the fan running after shutdown and flatten the battery overnight. A brief run-on after a hot shutdown can be normal on some vehicles, but prolonged running is not. A parasitic draw test with an ammeter in series with the negative cable will show whether the draw disappears when you pull the fan fuse.
Safety Before You Unplug Anything
Disconnect the negative battery cable before unplugging fan connectors or removing power module connectors, and keep hands, tools and clothing away from the blades. An electric fan can start without warning on a hot engine, sometimes even with the ignition off. On a 4xe, follow the shutdown procedure in the owner's manual and limit your work to the 12-volt battery and its circuits. Isolating the high-voltage system requires trained technicians, specific procedures and rated protective equipment, so leave orange cables and their components alone.
Limitations and Next Step
The locations above describe each generation's general layout, but cavity assignments and fan control hardware vary with engine, options and production changes. The cover label and the factory wiring diagram for your vehicle identification number are the reliable references. If testing points to a relay inside a JK TIPM, the fix is usually repairing or replacing the module, and a replacement may need programming with a capable scan tool. Many such tools can also command the fan on directly, which quickly separates a control problem from a power or motor problem.
If the engine is overheating, stop driving and let it cool before investigating. Overheating can come from low coolant, a stuck thermostat or a failing water pump just as easily as from the fan. Hand the job to a professional when the fault points to a control module, when the wiring has been heavily modified, or when any part of the diagnosis touches the high-voltage system on a 4xe.