The starter solenoid on a 1998 Ford Explorer is not a separate box you mount elsewhere; it is built into the starter motor itself. On that model, the starter sits on the passenger side of the engine near the bell housing, just above the transmission, and the solenoid is attached to the starter body. Access for inspection or replacement typically requires working from underneath with proper safety precautions.
What the starter solenoid does
The starter solenoid acts as a remote switch that engages the starter motor when you turn the key. When the ignition is in the Start position, the solenoid connects the battery to the starter windings, cranking the engine. If the solenoid fails, you may hear a click but the engine won’t crank, or the starter may fail to engage at all.
Where to look on a 1998 Explorer
To locate the starter and its solenoid on a typical 1998 Explorer with a 4.0L V6, follow these steps.
- Park on a flat surface, engage the parking brake, and disconnect the negative battery cable to avoid shorts.
- Lift the front end safely and support with jack stands as needed to gain access to the underside of the engine.
- Look at the passenger side of the engine where the bell housing meets the transmission; the starter motor is mounted there, toward the bottom of the engine bay.
- The solenoid is attached to the starter body. It is the small cylindrical unit with two large battery cable terminals on one end and a smaller terminal or wire lead for the ignition signal on the other.
- Trace the wiring: a thick positive battery cable typically lands on the solenoid's large terminal, and the thin wire from the ignition switch goes to the solenoid's trigger terminal.
Not every Explorer engine bay layout is identical, but on the 1998 4.0L V6, you will generally find the starter and its solenoid mounted on the passenger side near the bell housing, accessible from beneath the vehicle.
Note for the 4.0L engine variant
Whether your Explorer has the 4.0L OHV or another V6 option, the basic arrangement is the same: the solenoid is integrated into the starter body and shares the same mounting bolts as the starter. If you cannot see the starter assembly from above, light from below will usually reveal the cylindrical starter with the solenoid on its side or top.
Testing and troubleshooting
Before replacing parts, confirm the solenoid is receiving power and that grounds are solid. Use these checks to distinguish a bad solenoid from a battery or wiring issue.
- With the key in Start, listen for a distinct click from the starter area. A click often indicates the solenoid is engaging but not delivering power to the motor, or a separate starter fault.
- Check the battery voltage at the solenoid's small trigger terminal (you'll need a test light or multimeter). It should read ~12 volts when the key is in Start.
- Inspect battery connections and engine ground straps; corroded or loose connections can mimic solenoid failure by preventing current flow.
If the solenoid does not click and there is no voltage at the trigger terminal, inspect the ignition switch circuit and wiring back to the starter. If it clicks but the engine does not crank, the starter motor or solenoid may need replacement.
Summary
On a 1998 Ford Explorer, the starter solenoid is not a separate box in the engine bay; it is built into the starter, which is mounted on the passenger side near the bell housing. The solenoid has two large terminals for the battery feed and starter output and a smaller terminal for the ignition signal. Locating and testing the solenoid involves identifying the starter unit from beneath the vehicle, verifying power and ground connections, and distinguishing a solenoid issue from battery or wiring problems before replacing components.