GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century (China) (CNG) 🢒 Engine 🢒 Engine Electrical 🢒 Battery Is Undercharged or Overcharged

Step

Action

Value(s)

Yes

No

1
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the generator connector.
  3. Turn the ignition switch to the ON position.
  4. Connect a scan tool to the Data Link Connector (DLC).
  5. On the scan tool, perform the following:
    6. • Select: Powertrain Control Module (PCM)
    • Select: Special Functions.
    • Select: Engine Output Controls.
    • Select: GEN L Terminal.
    • Command the generator ON.
  6. Using a DMM, measure the voltage between the generator harness connector terminal B and ground.

Is the measured voltage within the specified range?

5 V

Go to Step 2

Go to Step 6

2

Using a DMM, measure the voltage between the generator BATT terminal and ground.

Is the voltage measured within the specified range?

9-14 V

Go to Step 3

Go to Step 9

3
  1. Reconnect the generator connector.
  2. Turn OFF all the accessories.
  3. Run the engine at idle speed.
  4. Using DMM, measure the voltage across the battery terminals.

Is the voltage measured within the specified range?

13-16 V

Go to Step 4

Go to Step 10

4

Load test the generator. Go to Charge Indicator Inoperative .

Does the generator operate properly?

--

Go to Step 5

Go to Step 10

5
  1. Replace the battery.Go to Battery Replacement .
  2. Recheck the system.

Is the repair complete?

--

Go to Charging System Check .

--

6

Inspect for a poor connection or an open in CKT 225.

Is there a poor connection or open in CKT 225?

--

Go to Step 7

Go to Step 8

7
  1. Repair a poor connection or an open in CKT 225.
  2. Recheck the system.

Is the repair complete?

--

Go to Charging System Check .

--

8
  1. The Powertrain Control Module (PCM) is not enabling CKT 225, thus disabling the generator. Go to Powertrain On Board Diagnostic (OBD) System Check .
  2. Recheck the system.

Is the repair complete?

--

Go to Charging System Check .

--

9
  1. Repair a poor connection or an open in CKT 2 or the fusible link to the generator BATT terminal.
  2. Recheck the system.

Is the repair complete?

--

Go to Charging System Check .

--

10

Replace the generator. Go to Generator Replacement for the service procedure.

Has the repair been made and the system rechecked?

--

Go to Charging System Check .

--