Open the engine compartment power panel near the battery and match slot numbers with the legend printed inside the cover before removing any protective insert.
This unit manages high-current circuits such as cooling fans, ignition feed, ABS module, and charging system. Each position is assigned a specific amperage value, typically ranging from 20A to 60A, depending on the load of the connected component.
The panel is secured with clips or a latch and sealed to protect internal contacts from moisture and debris. Inside, both relays and current protection elements are arranged in a structured layout, allowing quick identification of each circuit.
Use a multimeter to check voltage across both terminals of each insert while the ignition is active. A break in continuity indicates a failed component, while no voltage suggests an upstream issue such as a relay fault or wiring damage.
1998 Jeep Grand Cherokee Under Hood Fuse Box Layout and Relay Functions
Open the engine compartment power distribution unit near the battery and read the slot map on the cover before removing any current protection element or relay.
The layout is organized into sections where high-amperage inserts are placed along the outer edges, handling systems such as radiator fan, alternator output, and ABS pump. Inner rows typically support control circuits and ignition-related feeds.
Relay positions are grouped based on function, allowing quick identification of switching components tied to starting, fuel delivery, and cooling. Each relay uses standardized terminals, making temporary swaps possible for troubleshooting.
Primary relay roles
Starter relay engages the engine cranking system. Fuel pump relay supplies power to the injection system. Cooling fan relay activates based on temperature input. ASD relay controls ignition and injector circuits simultaneously.
High-load inserts in this unit usually range from 30A to 60A and protect circuits with continuous current draw. These include battery charging lines, main power feeds, and auxiliary systems such as heating elements.
Inspect terminals for discoloration, melting, or loose contact points before reinstalling components. A damaged connection can interrupt current flow and mimic a failed relay or insert, leading to incorrect diagnosis.
Exact location of under hood fuse box and how to open the cover safely
Find the power distribution unit next to the battery on the driver-side of the engine compartment and clear any dirt around the lid before opening it.
The housing is a rectangular plastic enclosure secured with side clips or a snap-lock mechanism. It is positioned close to the main power cable connection, making it easy to identify among other components.
Press the retaining tabs gently while lifting the cover upward. Avoid using excessive force, as the plastic clips can break or lose tension, leading to poor sealing after reinstallation.
Once opened, flip the cover to view the printed layout on the inside. This reference shows slot numbering, relay positions, and circuit assignments, allowing accurate identification of each component without guesswork.
After inspection or replacement, align the cover evenly and press down until all clips engage securely. A tight seal prevents moisture entry and protects internal contacts from corrosion and debris.