GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Monte Carlo 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Charging System Check

When the charging system is operating normally, the charge indicator lamp will come on when the ignition switch is turned on and will go out when the engine starts. If the lamp operates abnormally, refer to Instrument Cluster System Check in Instrument Panel, Gauges and Console. If an undercharged or overcharged battery condition occurs, refer to Battery Is Undercharged or Overcharged . Remember that an undercharged battery is often caused by accessories being left on overnight, or by a rear compartment or instrument panel compartment lamp that stays on.

Noise from a generator may be caused by the following components:

    • Improper routing of hoses, wiring or shielding against the generator housing.
    • A loose drive pulley
    • Loose mounting bolts
    • Worn or dirty bearings
    • A faulty diode
    • A faulty stator
    • Brush/slip ring friction

Precautions
    • Do not reverse the connections to the generator.
    • Do not short across, or ground any of the terminals in the charging circuit, except as directed by the instructions.
    • Do not attempt to hot wire the generator by connecting B+ voltage to any of the generator 4-way connector terminals. Use only an approved test harness as described in these instructions.
    • Never disconnect the output terminal while the generator is operating.
    • Use only approved Metri-pack terminal probe adapters to connect the meter leads and the jumper wires to the connector terminals. Using improper adapters will damage the concrete terminals and cause charging system or test harness failure.
    • Before connecting a charger or a booster battery to the vehicle battery, refer to Battery Charging .

Inspection

Before testing the generator inspect the following components and conditions:

    • Battery. Verify that the vehicle battery is in good condition and fully charged. Refer to Battery Check .
    • Built-in hydrometer in the battery. The green eye must be showing in the hydrometer.
    • The voltage across the battery terminals with all loads OFF should be above 12 volts.
    • Verify that the battery connections are clean and tight.
    • Drive belt for damage or looseness.
    • Wiring harness at the generator. Verify that the harness connector is tight and latched. Verify that the output terminal of the generator is connected to the vehicle battery positive generator lead.
    • All charging system related fuses and electrical connections for damage or looseness. Refer to Engine Electrical Schematic References .

Generator Assembly

Tools Required

J 41450-B J 41450-B

To diagnose a CS generator perform the following procedure:

CS Generator Diagnosis

Step

Action

Value(s)

Yes

No

1
  1. Turn the ignition switch to the OFF position.
  2. Turn all the accessory loads OFF.
  3. Turn the load in the carbon pile load tester all the way OFF.
  4. Connect a load test across the battery terminals.

    5. Ensure the ammeter clip is placed for the entire generator output to pass through the clip. Refer to Starting and Charging Schematics . If the circuits are split so that any of the current can pass through parallel circuits, all such circuits must pass through the clip or the generator output reading on the inductive ammeter will not be accurate.

  5. Install the inductive ammeter around the output wire(s) of the generator.
  6. Perform the universal self-test procedure per the manufacturer's instructions in order to verify proper operation of the tester.
  7. Connect the red alligator clip of the tester to the generator output terminal.
  8. Connect the black clip to the metal generator housing.

    9. The green power lamp on the tester should light.

Does the green power lamp light?

--

Go to Step 6

Go to Step 2

2

Use a digital multimeter (DMM) in order to check the voltage between the generator output terminal and the battery negative terminal. The reading should be B+ voltage.

Is the reading as specified?

B+

Go to Step 4

Go to Step 3

3
  1. Inspect for an open fusible link or an open condition in the generator output wiring.
  2. Repair as needed.
  3. The tester's green power lamp should now light when connected as described in step 1.

Does the green POWER lamp light?

--

Go to Step 6

Go to Step 4

4

With the tester still connected as described in step 1, connect a jumper wire between the generator metal housing and the battery negative terminal. The green POWER lamp on the tester should light.

Does the green POWER lamp light?

--

Go to Step 6

Go to Step 5

5

Inspect the ground path from the generator housing to the battery negative terminal for an open condition. Repair as needed.

Does the green POWER lamp light?

--

Go to Step 6

Go to Step 1

6
  1. With the tester still connected as described in step 1, disconnect the 4-way generator connector from the generator.
  2. Connect the matching connector on the tester to the generator. The red DIAGNOSTIC lamp on the tester should light.

Does the red DIAGNOSTIC lamp light?

--

Go to Step 8

Go to Step 7

7
  1. Disconnect the 4-way tester connector from the generator.
  2. With the ignition switch in the RUN position (engine stopped), use a fused jumper lead (with a 5 ampere fuse) and Metri-pack 150 terminal probe adapter to ground the L terminal (cavity B) in the vehicle harness 4-way connector.
  3. If the fuse does not blow, replace the generator.
  4. If the fuse blows, diagnose and repair the L terminal CKT 225 for direct short to B+ or mis-wired/no resistance condition, then replace the generator. Refer to Starting and Charging Schematics .
  5. Fix the wiring before replacing the generator.

Does the fuse blow?

--

Go to Starting and Charging Schematics or Generator Replacement or Generator Replacement or Generator Replacement

Go to Generator Replacement or Generator Replacement or Generator Replacement

8
  1. Turn all the electrical accessories to the OFF position.
  2. Close the doors.
  3. Ensure all the loads are OFF.
  4. With the tester connected as described in step 6, start the engine and let the engine idle briefly. (The vehicle's generator control circuits are bypassed during this test and the charge indicator in the instrument cluster will not operate normally.)
  5. After the engine starts and the red DIAGNOSTIC lamp on the tester should not be lit.

Does the red DIAGNOSTIC lamp light?

--

Go to Generator Replacement or Generator Replacement or Generator Replacement

Go to Step 9

9

Increase the engine speed to 2500 RPM. The red DIAGNOSTIC lamp on the tester should not light.

Does the red DIAGNOSTIC lamp light?

--

Go to Generator Replacement or Generator Replacement or Generator Replacement

Go to Step 10

10
  1. With the engine speed still at 2500 RPM, turn the load on the carbon pile load tester to ON.
  2. Adjust until the generator output is at the load test value. Refer to Generator Assembly Bench Check . If the red DIAGNOSTIC lamp on the tester lights with the generator operating at or below the load test output value, replace the generator. If the red light does not light and the load test value is attained, the generator is good.

Does the red DIAGNOSTIC lamp light?

--

Go to Generator Replacement or Generator Replacement or Generator Replacement

--

  1. Turn the carbon pile load tester to OFF.
  2. Stop the engine.
  3. Remove the generator tester, the ammeter and the load tester from the vehicle.
  4. Connect the 4-way harness connector to the generator. Ensure the harness is fully seated and latched.
  5. If the customer has commented about erratic or high voltage from a generator that uses an S terminal connection, inspect the S terminal circuit (cavity D in the harness connector) for intermittent or high resistance conditions.
  6. If the customer has commented about a battery that loses charge over a period of time, refer to Battery Electrical Drain/Parasitic Load Test .