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HOMESERVICE MANUALSPONTIAC2008GRAND PRIX BASEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 336 (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESCHARGING SYSTEM TEST
2008 Pontiac Grand Prix Base

Charging System Test

2008 Pontiac Grand Prix BaseSECTION Charging System Test
WARNING: This page is about a different car, the 2008 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
Step Action Value(s) Yes No
Schematic Reference: Starting and Charging Schematics 
1 Did you review the Diagnostic Starting Point for Engine Electrical and perform the necessary inspections? - Go to Step 2  Go to Diagnostic Starting Point - Engine Electrical 
2
IMPORTANT: The battery must be above a 70 percent state of charge.
Did you perform the Battery Inspection Test?		 - Go to Step 3  Go to Battery Inspection/Test 
3
  1. Install a scan tool.
  2. Start the engine.
  3. Turn ON the following accessories:
    • Headlights (high beams)
    • A/C on Max
    • Blower fan (on high)
  4. Increase engine speed to 2,500 RPM.
  5. Measure the voltage between the generator output terminal and ground.
Is the voltage measured within the specified value?		 12.0-15.5 V Go to Step 4  Go to Step 5 
4
  1. Turn OFF all accessories.
  2. Turn OFF the ignition.
    3. CAUTION: Make sure that the load is completely turned off before connecting or disconnecting a carbon pile load tester to the battery. Otherwise, sparking could ignite battery gasses which are extremely flammable and may explode violently.
  3. Connect a carbon pile tester to the vehicle. Follow the manufacturer's instructions.
    4. IMPORTANT: When measuring generator output current, be sure the inductive probe encircles the generator output wire.
  4. Connect an inductive ammeter probe to the output circuit of the generator.
  5. Start the engine.
  6. Increase engine speed to 2,500 RPM.
  7. Adjust the carbon pile as necessary in order to obtain the maximum current output.
Is the generator output greater than or equal to the load test value as specified in Generator Usage  ?		 - Go to Step 15  Go to Step 6 
5 Is the voltage measured greater than the specified value? 15.5 V Go to Step 9  Go to Step 6 
6
  1. Turn OFF the accessories.
  2. Turn OFF the ignition.
  3. Disconnect the generator harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage between the generator turn ON signal circuit, terminal 2, of the generator harness connector and ground.
Does the voltage measure near the specified value?		 B+ Go to Step 7  Go to Step 11 
7
  1. Reconnect the generator harness connector.
  2. Start the engine.
  3. Turn ON the vehicle accessories.
  4. Increase the engine speed at 2,500 RPM.
  5. Measure the voltage drop between the generator output terminal and the battery positive terminal.
Is the voltage above the specified value?		 0.5 V Go to Step 12  Go to Step 8 
8
  1. Maintain the engine speed at 2,500 RPM.
  2. Measure the voltage drop between the battery negative terminal and the generator metal housing.
Is the voltage above the specified value?		 0.5 V Go to Step 13  Go to Step 10 
9 Test the sense circuit of the generator for a high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 10 
10 Inspect for poor connection at the generator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 15  Go to Step 14 
11 Repair the high resistance or open in the generator turn ON signal circuit. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 15  -
12 Repair the high resistance in the battery positive circuit between the generator output terminal and the battery positive terminal. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 15  -
13 Repair the high resistance in the ground circuit between the generator housing and the battery negative terminal. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 15  -
14 Replace the generator. Refer to Generator Replacement .
Did you complete the repair?		 - Go to Step 15  -
15 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 1 
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.