LS 2006



The alternator on this vehicle has a built-in voltage regulator set point. The alternator decides optimal charging system voltage based on temperature. The alternator has a communication line (GEN MON) to the powertrain control module (PCM), which indicates the alternator operating duty cycle. This is a pulse width modulated (PWM) signal. The communication line (GEN MON) is used for fault indication as well. The alternator has an I-terminal used for initially turning on the alternator. The alternator also has a battery sense terminal (A-terminal).

Alternator output voltage is supplied through the battery positive (B+) output terminal on the rear of the alternator to the battery and the electrical system.

The battery voltage sense or A-circuit is used to sense battery voltage.

The alternator I-circuit terminal is used to turn the alternator on initially. Once the alternator is turned on, the alternator only turns off when the engine is shut down. If the I-circuit 10-BA25 (GY/RD) is open or shorted to ground, the alternator does not function. If the engine speed exceeds 3,000 rpm, the alternator self-excites, and begins to function normally (the battery light turns off and the alternator operates normally) until the engine is turned off. This is a limp-home mode for customer safety.

The alternator monitor (GEN MON) communicates the alternator load and error conditions to the PCM. The PCM sends a signal to the instrument cluster using the Standard Corporate Protocol (SCP) bus to turn on the charging system warning indicator if there is an error condition.

Diagnosis & Testing

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Fig. Alternator Connector

  1. Before servicing the vehicle, refer to the Precautions section.
  3. Check the alternator wiring as follows:
    1. Pin 1:

      0 volts with key OFF .
      10-14 volts with key ON , engine OFF .
      6-12 volts during start.
      Alternating between 1-15 volts with the engine running.

    3. Pin 2:

      0 volts with the key OFF .
      0 volts with the key ON , engine OFF .
      0.1-4 volts during start.
      1-8 volts with the engine running.

    5. Pin 3:

      12 volts with the key ON , engine OFF .
      10-12 volts during start.
      13-15 volts with the engine running.



Removal & Installation

3.9L Engine
  1. Before servicing the vehicle, refer to the Precautions section.
    The A/C suction line may need to be positioned rearward to ease removal of the alternator.

  3. Disconnect the negative battery cable.
  5. Rotate the front end accessory drive belt tensioner counterclockwise and position the belt aside.
  7. Remove the front valance panel.
  9. Remove the air deflector.
  11. Remove the A/C suction line clip from the radiator core support.
  13. Remove the left hand A/C suction line lower bracket bolt and position the bracket rearward.
  15. Remove the alternator upper mounting bolt.
  17. Remove the alternator lower mounting nut and bolt.
  19. Disconnect the alternator electrical connector.
  21. Position the alternator B+ wire protective cover aside and remove the alternator B+ wire nut and cable end.
  23. Remove the alternator.

To install:

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Fig. Alternator torque sequence-3.9L engine

To install:

  1. Install the alternator harness connectors, then install the alternator. Tighten the bolts in sequence as follows:
    1. Step 1: Tighten bolt No. 1 to 35 ft. lbs. (48 Nm)
    3. Step 2: Tighten bolt No. 2 to 15 ft. lbs. (20 Nm) plus 90 degrees
    5. Step 3: Tighten bolt No. 3 to 35 ft. lbs. (48 Nm)

  3. Install or connect the following:

    Lower splash shield
    Accessory drive belt
    Air intake tube
    Negative battery cable

  5. Please note the following specifications:

    1. Alternator B+ wire nut to 71 inch lbs. (8 Nm).
    3. Alternator lower mounting nut and bolt. Tighten to 33 ft. lbs. (45 Nm).
    5. Alternator upper mounting bolt. Tighten to 15 ft. lbs. (21 Nm).
    7. Left hand A/C suction line lower bracket bolt. Tighten to 89 inch lbs. (10 Nm).