Easy Step-by-Step Replacement of the Alternator in a 2003 Mazda Protege

The alternator on your 2003 Protege performs two main equally important functions: to provide the juice needed to power all the electronics in the car and to use the excess power it produces to maintain and recharge the battery, as needed. The alternator has two key values that require testing to verify if it has failed voltage and amps. The idle voltage on the alternator should be between 13 and 15 volts, whereas the amps should be between 0 and 59 at 1,000 rpm, and between 0 and 77 at 2,000 rpm. If either test fails on your 2003 Protege, replace the alternator.

Instructions

1

Loosen the negative battery cable end with a combination wrench and pull the negative cable from the battery. Position it out of the way to prevent accidental reconnection.

2

Remove the power wire from the alternator by loosening its retaining nut with a ratchet and socket and pulling the wire from its stud. Press and hold the unlocking button on the alternator wiring harness and pull the harness from the alternator.

3

Loosen the upper and lower mounting bolts on the alternator, using a ratchet and socket. The lower bolt goes through the rear of the lower alternator mount and the upper bolt goes through the alternators adjuster bracket.

4

Relieve the tension on the alternator drive belt by turning the adjusting bolt clockwise with a ratchet and socket. Continue loosening the adjuster bolt until the drive belt is loose enough to slide off the alternator pulley.

5

Pull the belt from the alternator pulley, but leave it attached to the remaining pulleys.

6

Remove the upper and lower alternator bolts with a ratchet and socket, and pull the alternator from the Proteges engine compartment.

7

Guide the new alternator into the engine compartment, inserting the mount on the bottom of the alternator into the mount on the engine. Insert the lower alternator bolt through the bolt holes in the bottom of the alternator and its bracket, then hand-thread the lower alternator bolt.

8

Pivot the alternator upward and align its upper bolt-hole with the bolt-hole in the alternator adjuster bracket. Hand-thread the upper alternator mounting bolt.

9

Route the drive belt back over the alternator pulley, then turn the adjuster bolt counterclockwise until the belt reaches its correct tension of just over a 1/4 inch 0.26 to 0.29 inches to be precise of deflection at the middle of its longest span between pulleys.

10

Tighten the upper alternator mounting bolts to between 14 and 18 foot-pounds and the lower alternator mounting bolts to be between 28 and 38 foot-pounds, using a torque wrench and socket. The upper bolt also acts as the locking bolt for the belt adjuster.

11

Plug the wiring harness into the rear of the new alternator. Guide the alternator power wire onto its mounting stud and hand-thread its nut. Tighten the power wire nut to between 8 and 11 foot-pounds with a torque wrench and socket.

12

Reconnect the negative battery cable end to the negative battery terminal and tighten its pinch bolt with a combination wrench.