Identifying a Jeep Cooling Fan Relay by Model and Year
When a Jeep's electric radiator fan stops running, or will not shut off, the relay that switches it is one of the first parts owners look for. Finding it is not always simple. Depending on the generation, the fan may be switched by a plug-in relay, by circuitry built into an under-hood power module, or by an electronic fan controller with no conventional relay at all. This guide explains how to tell which setup your Jeep uses and how to check it safely.
Where the Jeep Fan Relay Is Usually Found
On most Jeep models, the cooling fan circuit is fed from the under-hood power distribution center, the fuse and relay box mounted near the battery. What you find inside depends on the model and year. Older designs typically use separate plug-in relays, and the legend on the underside of the box lid shows which position belongs to the radiator fan. Many later vehicles use an integrated power module, often called a TIPM, where the fan relay may be part of the module's internal circuitry rather than a removable part. Newer designs frequently drive the fan through a pulse-width-modulated fan control module mounted on or near the fan shroud, which varies fan speed electronically.
Some vehicles also use more than one relay, for example separate low-speed and high-speed fan circuits. Because layouts can change within a single generation, the most reliable way to identify the correct part is a parts lookup by your vehicle identification number, combined with the lid legend and the fuse chart in the owner's manual. Do not rely on a relay position described for a different year or engine.
How the Fan Relay Circuit Works
A relay lets a small control current switch a much larger load. The fan motor draws far more current than the engine computer can handle directly, so the powertrain control module controls only the relay coil. On a common mini relay, the coil terminals are usually marked 85 and 86, while the switched contacts are 30 and 87. When the computer decides the engine needs airflow, based on inputs such as coolant temperature and air conditioning demand, it energizes the coil. The contacts close and send battery power through a high-current fuse to the fan motor.
Electronically controlled fans work differently. The computer sends a command signal to the fan control module, and the module adjusts motor speed rather than simply switching it on and off. In these systems you may not hear a relay click, and the relay, if one exists, may only supply power to the module. The wiring diagram for your exact vehicle shows whether the circuit uses a conventional relay, an integrated module output, a fan control module, or a combination.
What Changes the Answer
Model, year and generation matter most, but engine choice and equipment can also change the fan circuit. Some Jeeps rely mainly on an engine-driven mechanical fan and use an electric fan only as an auxiliary unit, often tied to air conditioning operation. Others depend entirely on electric fans. Towing or heavy-duty cooling packages, different engines in the same model, and mid-cycle updates can each change relay count, fuse rating or module design. Aftermarket accessories such as winch wiring, auxiliary lighting, remote start systems or aftermarket fan controllers can also alter how the circuit behaves.
Plug-in hybrid 4xe models need extra care. The radiator fan, its relay or module, and the control electronics run on the conventional 12-volt system, supplied by the low-voltage auxiliary battery. That battery is completely separate from the high-voltage traction battery and its orange-sheathed cables and components. Fan relay diagnosis on these vehicles stays within the 12-volt circuit. Never open, probe or disconnect high-voltage components or orange cables, and remember that hybrid vehicles may have additional cooling circuits for the battery and power electronics with their own controls.
How to Identify and Check the Relay Yourself
Start by opening the power distribution center and reading the lid legend. If you find a removable relay labeled for the radiator or cooling fan, note the part number printed on it. A common quick test is to swap it with an identical relay that has the same part number and serves a non-critical circuit, then see whether the fan behavior changes. Check the fan fuse at the same time and confirm its fuse rating matches the legend. Never install a larger fuse to stop a fuse from blowing, because a blowing fuse usually points to a shorted motor or wiring fault.
If the relay and fuse look fine, measure system voltage at the battery terminals with a multimeter. A healthy battery at rest typically reads around 12.6 volts, and charging output with the engine running is usually in the range of roughly 13.5 to 14.7 volts. Low system voltage can make fan problems look intermittent. With the fan commanded on, which many systems do when air conditioning is switched to maximum, a voltage drop test across the relay contacts or along the fan power and ground wires reveals resistance that a simple continuity check can miss. A drop of more than a few tenths of a volt across a connection deserves attention. Avoid jumping terminals inside an integrated power module socket unless the service information specifies it, as the wrong terminal can damage the module.
Before unplugging the fan motor, removing a power module or working near the fan, disconnect the negative battery cable. Electric fans on some vehicles can start without warning, even with the ignition off, so keep hands and tools clear of the blades. If the fan keeps running long after shutdown or the battery goes flat overnight, a relay with stuck contacts may be causing parasitic draw. Measuring draw with an ammeter in series with the battery, then pulling the fan relay or fuse to see whether the reading falls, helps confirm it.
Limitations and the Next Step
Relay positions, part numbers and control strategies vary too much across Jeep models and years to identify a specific relay reliably without vehicle-specific information. Where the fan switching is built into an integrated power module, an apparent relay failure may actually be a module fault, a computer command problem or a sensor input issue, and confirming it often requires a scan tool that can command the fan and read its status. A replacement module may also need configuration or programming before it works correctly, which can mean a dealer or a well-equipped independent shop.
The practical next step is to gather your VIN, read the legend on your power distribution center, and obtain the service wiring diagram for your exact model, year and engine. With that information, you can confirm whether your Jeep uses a replaceable relay, an integrated module output or a fan control module, and test the right part. If the vehicle is a plug-in hybrid and any work approaches high-voltage components, or if overheating continues after basic checks, stop driving it and have it inspected by a qualified technician.