The Jeep Compass has established itself as a versatile compact SUV that appeals to drivers seeking a balance of on-road comfort and off-road capability. One of the key systems that keeps this vehicle running reliably is the electrical infrastructure, particularly the underhood fuse box and relay panel. Understanding the layout, specifications, and function of these components is essential for diagnosing electrical issues, performing routine maintenance, and ensuring the longevity of your vehicle's electrical systems. This guide provides a comprehensive look at the underhood fuse box and relay specifications for the Jeep Compass, covering location, common components, diagnostic tips, and replacement procedures.

Location and Access to the Underhood Fuse Box

In most Jeep Compass models, the underhood fuse box is positioned in the engine bay on the driver's side, near the battery. It is typically a black plastic box with a removable lid. Access is straightforward: open the hood, locate the fuse box, and release the retaining clips or tabs on the lid. Some models may require removing a plastic cover or moving aside wiring harnesses for full access. The inside of the lid often contains a diagram or a label identifying the position and rating of each fuse and relay.

Identifying Your Specific Model Year

The exact location and layout of the underhood fuse box can vary slightly depending on the model year and trim level. For example, the first-generation Compass (2007–2016) and the second-generation Compass (2017–present) have different fuse box configurations. Always consult your owner's manual or the diagram printed on the fuse box lid for model-specific information. Online resources such as Jeep's official owner manuals can also provide precise details for your vehicle.

Fuse Box Layout and Components

The underhood fuse box houses a variety of fuses and relays that protect and control high-current circuits. Here is a breakdown of the typical components you will find:

  • Blade fuses: These are the most common type, available in mini, micro, and maxi sizes. They protect circuits ranging from 5A to 60A.
  • Relays: Electro-mechanical switches that manage high-current devices like the radiator fan, fuel pump, starter motor, and horn. Most relays in the Compass are standard ISO relays rated for 30A or 40A.
  • Bus bars: Internal metal strips that distribute power from the battery to multiple fuse positions.
  • Connectors: These allow the fuse box to interface with the vehicle's main wiring harness.
  • Spare fuse slots: Some fuse boxes include spare fuses and a fuse puller tool for convenience.

Fuse Box Diagram Overview

A typical underhood fuse box diagram for a 2018 Jeep Compass might include the following circuits:

  • J1: Radiator Fan Relay
  • J2: Fuel Pump Relay
  • J3: Starter Relay
  • J4: Horn Relay
  • F1: 30A – Power Window System
  • F2: 40A – Engine Cooling Fan
  • F3: 20A – Fuel Pump
  • F4: 15A – Horn
  • F5: 10A – Engine Control Module (ECM)
  • F6: 25A – Rear Window Defogger

Note that these values are examples only. Always verify the specific ratings for your model year using the diagram on the fuse box lid or your owner's manual.

Common Fuse and Relay Specifications

The electrical system in the Jeep Compass operates on a 12-volt DC platform. Fuses are rated by amperage, which indicates the maximum current they can safely carry before blowing. Relays are rated for the load they can switch. Below are typical specifications found in the underhood fuse box:

Component Type Rating Function
Engine Control Module (ECM) Fuse 10A–15A Powers the engine control unit
Fuel Pump Fuse 20A Supplies power to the fuel pump
Radiator Fan Fuse / Relay 30A–40A fuse, 30A relay Controls engine cooling fan
Starter Motor Relay 30A relay Engages the starter solenoid
Horn Fuse / Relay 15A fuse, 20A relay Powers the horn
Headlights Fuse 15A–20A each Powers low and high beam circuits
Windshield Wipers Fuse 20A–25A Controls wiper motor

Always replace a fuse with one of the same amperage rating. Using a higher-rated fuse can cause wire damage or fire. Using a lower-rated fuse may cause nuisance blowing.

Diagnosing Blown Fuses and Faulty Relays

Electrical problems in the Jeep Compass often trace back to a blown fuse or a failing relay. Common symptoms include:

  • A specific circuit stops working (e.g., headlights, horn, wipers).
  • The engine cranks but does not start (fuel pump relay issue).
  • The cooling fan does not engage when the engine is hot.
  • Clicking noises from the fuse box when attempting to use a function.

Testing a Fuse

To check a fuse, use a test light or a multimeter set to continuity mode. With the ignition off, probe the small metal test points on the top of the fuse. If power is present on both sides, the fuse is good. If only one side has power, the fuse is blown. A visual inspection can also reveal a broken metal strip inside the fuse.

Testing a Relay

Relays are more complex to test. A basic method involves swapping the suspect relay with a known working relay of the same type (e.g., horn relay with fog light relay if they share ratings). If the problem moves, the relay is bad. For a more precise test, use a multimeter to check for continuity between the relay coil terminals and the switch terminals. A detailed guide on relay testing can be found at Electrical101.

How to Replace Fuses and Relays

Replacing a fuse or relay is a simple process that requires minimal tools. Follow these steps:

  1. Safety first: Turn off the engine and remove the key. Disconnect the negative battery terminal if you are working on high-current circuits.
  2. Locate the correct component: Use the fuse box diagram to identify the fuse or relay.
  3. Remove the fuse or relay: Use a fuse puller (often stored in the fuse box or your tool kit) for fuses. For relays, grasp the relay firmly and rock it gently side to side while pulling upward.
  4. Inspect: Check the removed component for visible damage. For fuses, look for a broken wire. For relays, listen for a clicking sound when 12V is applied to the coil (outside the vehicle).
  5. Install the replacement: Insert the new fuse or relay firmly into the socket. Ensure it is the correct rating and type.
  6. Test: Reconnect the battery (if disconnected) and test the circuit.
  7. Secure the cover: Replace the fuse box lid to protect against moisture and debris.

Finding Replacement Parts

Replacement fuses and relays are available at auto parts stores, dealerships, and online retailers. Jeep uses standard blade-type fuses (ATO, ATC, mini, and maxi) and standard ISO relays. It is wise to keep a few common spares in the vehicle. Websites like AutoZone carry a wide selection of automotive fuses and relays.

Model Year Variations

The underhood fuse box has evolved across the Jeep Compass generations. Understanding these differences can help when diagnosing issues or looking up diagrams.

First Generation (2007–2016)

The first-generation Compass shares its platform with the Dodge Caliber. Its underhood fuse box is located on the driver's side near the strut tower. It uses mostly mini and standard ATO fuses. Common relay locations include fuel pump, starter, and radiator fan. The fuse box diagram is printed on the lid and in the owner manual.

Second Generation (2017–Present)

The redesigned Compass features a more integrated electrical system with additional electronic controls. The underhood fuse box still resides on the driver's side but may include more micro fuses and several high-current relays. The layout is often more compact. Some circuits that were previously fused are now managed by the Totally Integrated Power Module (TIPM) or a similar smart fuse box. This means some fuses may be internal and not user-serviceable.

Special Models (Trailhawk, Latitude, Limited)

Higher trim levels may have additional circuits for features like heated seats, panoramic sunroof, or advanced driver-assistance systems. These circuits may have their own fuses and relays in the underhood box or secondary fuse panels located elsewhere, such as under the dashboard or in the cargo area.

Safety Precautions

Working with the vehicle's electrical system requires caution. Follow these safety guidelines:

  • Always disconnect the negative battery cable before starting any repair that involves direct contact with the fuse box or wiring.
  • Never replace a fuse with one that has a higher amperage rating than specified. This can cause wire overheating and fire.
  • Avoid using metal tools to extract fuses when a plastic puller is available. This prevents short circuits.
  • Keep the fuse box cover installed when the engine is running to protect against water ingress.
  • If a new fuse blows immediately after replacement, there is likely a short circuit elsewhere in the system. Consult a professional technician.

If you are unsure about any step, refer to the Jeep Compass service manual or seek help from a certified mechanic.

Frequently Asked Questions

What kind of fuses does a Jeep Compass use?

The Jeep Compass primarily uses blade-type fuses in standard (ATO/ATC), mini, and micro sizes. Maxi fuses are used for high-current circuits like the cooling fan. Relays are standard ISO types rated for 30A or 40A.

How do I know if a relay is bad?

Common signs include a non-functioning component (e.g., fuel pump not running, fan not spinning), a clicking sound from the relay when activated but no operation, or visible damage such as melted housing. Relay testers are available for more accurate diagnosis.

Can I drive with a blown fuse?

It depends on the circuit. A blown fuse for the radio or interior lights is not critical. However, a blown fuse for the engine control module, fuel pump, or cooling fan can cause the vehicle to stall or overheat. Address any non-essential fuse issues as soon as convenient, and essential ones immediately.

Where can I find the fuse box diagram for my specific model?

The diagram is usually printed on the underside of the fuse box lid or in the owner's manual. If you have lost your manual, you can download a PDF from the Jeep owner resources page using your VIN.

Conclusion

The underhood fuse box and relay system in the Jeep Compass is a critical component of the vehicle's electrical architecture. By familiarizing yourself with its location, layout, and specifications, you can efficiently troubleshoot common electrical problems, perform safe replacements, and maintain your vehicle in top condition. Always use the correct replacement parts and ratings, and keep a copy of your fuse box diagram handy. With this knowledge, you can handle many electrical issues that may arise during the life of your Compass, saving time and money on unnecessary service visits.