Alternator: Description and Operation

The charging system consists of:
A. Generator (GEN).
B. Integral voltage regulator.

The generator provides direct current current to charge the battery. The generator has an integral voltage regulator.

These vehicles use the 4G type of generators. The 4G generator has no replaceable parts and must be replaced as an assembly. The generator amperage ratings are the following:
1. 58 Amps @ 1500 RPM/120 Amps @ 5000 RPM.
2. 45 Amps @ 1500 RPM/110 Amps @ 5000 RPM.
3. 35 Amps @ 1500 RPM/90 Amps @ 5000 RPM.

Generator With Integral Rear Mount Voltage Regulator-internal Fan Type
when the engine is started, the generator (GEN) generates alternating current (AC) which is converted to direct current (DC) by the rectifier assembly internal to the generator. This current is then supplied to the vehicle electrical system through the battery positive voltage (B+) wire located on the rear of the generator.

Once the generator begins generating current, a voltage signal is taken from the generator stator and coil and is fed back to the voltage regulator S circuit (stator feedback), turning off the charge indicator.

when the system is functioning normally, the generator output current is determined by the voltage at the A-circuit (battery sense voltage). The A-circuit voltage is compared to a set voltage internal to the generator. The generator controls the generator field current to maintain proper generator output. The set voltage will vary with the temperature and is typically higher in the winter than in the summer. This allows for better battery recharge in the winter and reduces the chance of overcharging in the summer.

Circuit Protection
These vehicles use fuseable links in the Generator (GEN) output circuit and a fuse in the voltage regulator A-circuit. Because of its high output capacity, the 58/120-amp generator has two fuseable links in the output circuit.

Fuseable links are several wire gauge sizes smaller than the circuit they protect. The fuseable links for the GEN are gray 12-gauge wires.

When fuseable links burn out, the generator and wiring is protected from heavy reverse current flows, such as incorrectly connected booster batteries, or short to ground in the wiring harness.

A burned-out fuseable link may have bare wire ends protruding from the insulation or bubbled insulation with illegible identification. If it is difficult to determine whether or not the fuseable link is burned out, replace the fuseable link.

Fuseable links have a flag molded on the wire or on the terminal insulator. Color identification of the flag is gray 12-gauge wire.