Starter motor. Starter relay

Starter motor


The starter motors used for the 4.7L engines are not interchangeable with the starter motors used for the other available engines for this model. The starter motors used for all 5.2L and 5.9L engines available in this model are interchangeable.

The 4.7L engine starter motor is mounted with two screws to the automatic transmission torque converter housing on the left side of the engine. The starter motors for all of the remaining engines are mounted with one screw, a stud and a nut to the automatic transmission torque converter housing and are also located on the left side of the engine.

Each of these starter motors incorporates several of the same features to create a reliable, efficient, compact, lightweight and powerful unit. The electric motors of both starters have four brushes contacting the motor commutator. These starter motors use four electromagnetic field coils wound around four pole shoes. The starter motors are rated at 1.4 kilowatts (about 1.9 horsepower) output at 12 volts.

These starter motors are serviced only as a unit with their starter solenoids, and cannot be repaired.

If either component is faulty or damaged, the entire starter motor and starter solenoid unit must be replaced.


These starter motors are equipped with a gear reduction (intermediate transmission) system. The gear reduction system consists of a gear that is integral to the output end of the electric motor armature shaft that is in continual engagement with a larger gear that is splined to the input end of the starter pinion gear shaft. This feature makes it possible to reduce the dimensions of the starter. At the same time, it allows higher armature rotational speed and delivers increased torque through the starter pinion gear to the starter ring gear.

The starter motors for all engines are activated by an integral heavy duty starter solenoid switch mounted to the overrunning clutch housing. This electromechanical switch connects and disconnects the feed of battery voltage to the starter motor and actuates a shift fork that engages and disengages the starter pinion gear with the starter ring gear.

These starter motors use an overrunning clutch and starter pinion gear unit to engage and drive a starter ring gear that is integral to the torque converter or torque converter drive plate mounted on the rear crankshaft flange.

Starter relay


The starter relay is an electromechanical device that switches battery current to the pull-in coil of the starter solenoid when the ignition switch is turned to the Start position. The starter relay is located in the Power Distribution Center (PDC), in the engine compartment.

See the fuse and relay layout label affixed to the inside surface of the PDC cover for starter relay identification and location.

The starter relay is a International Standards Organization (ISO) micro-relay. Relays conforming to the ISO specifications have common physical dimensions, current capacities, terminal patterns, and terminal functions. The ISO micro-relay terminal functions are the same as a conventional ISO relay.

However, the ISO micro-relay terminal pattern (or footprint) is different, the current capacity is lower, and the physical dimensions are smaller than those of the conventional ISO relay.

The starter relay cannot be repaired or adjusted and, if faulty or damaged, it must be replaced.


The ISO relay consists of an electromagnetic coil, a resistor or diode, and three (two fixed and one movable) electrical contacts. The movable (common feed) relay contact is held against one of the fixed contacts (normally closed) by spring pressure. When the electromagnetic coil is energized, it draws the movable contact away from the normally closed fixed contact, and holds it against the other (normally open) fixed contact.

When the electromagnetic coil is de-energized, spring pressure returns the movable contact to the normally closed position. The resistor or diode is connected in parallel with the electromagnetic coil in the relay, and helps to dissipate voltage spikes that are produced when the coil is de-energized.

    Dodge Durango (DN) 1998-2003 Service Manual


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