GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2000 🢒 S/T Isuzu - 2WD 🢒 Engine 🢒 Engine Electrical 🢒 Voltmeter Displaying High or Low

Step

Action

Value(s)

Yes

No

1

Did you review the charging system operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms

2

Verify that the voltmeter is displaying HIGH or LOW.

Is the voltmeter operating normally?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn all of the electrical loads OFF.
  2. Start the engine.
  3. Briefly idle the engine.
  4. Use a scan tool in order to inspect the charging voltage.

Is the voltage within the specified range?

13-16 V

Go to Step 4

Go to Step 7

4

Compare the scan tool reading with a reading obtained at the same time (engine at idle) from the vehicle voltmeter.

Is the difference between the vehicle voltmeter reading and the scan tool reading within the specified range?

2 V

Go to Step 5

Go to Step 8

5
  1. Increase the engine speed to 2500 RPM.
  2. Use a scan tool in order to inspect the charging voltage.

Is the voltage within the specified range?

13-16 V

Go to Step 6

Go to Step 7

6

Compare the scan tool reading with a reading obtained at the same time (engine at 2500 RPM) from the vehicle voltmeter.

Is the difference between the vehicle voltmeter reading and the scan tool reading within the specified range?

2 V

Go to Step 14

Go to Step 8

7

Refer to Generator Not Operating Properly .

Is the generator OK?

--

Go to Step 12

Go to Step 13

8

Inspect the instrument cluster for an incorrect voltmeter reading condition.

Is the instrument cluster operating properly?

--

Go to Step 10

Go to Step 9

9

Repair the instrument cluster as necessary Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

Go to Step 14

--

10

Inspect the PCM or the VCM for an incorrect voltmeter reading condition.

Is the PCM or VCM operating properly?

--

Go to Step 12

Go to Step 11

11

Repair the PCM or the VCM as necessary Refer to VCM Replacement/Programming or Powertrain Control Module Replacement in Engine Controls.

Is the repair complete?

--

Go to Step 14

--

12
  1. Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection Disconnect and clean all of the connections between the battery positive terminal and the generator output terminal.
  2. Disconnect and clean all of the connections in the ground circuit between the battery negative terminal and the generator housing.
  3. Inspect all of the cables for an intermittent open condition.
  4. Connect the battery negative cable.

Is the repair complete?

--

Go to Step 14

--

13

Replace the generator. Refer to Generator Replacement .

Is the repair complete?

--

Go to Step 14

--

14

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3