Various Driveability Symptoms, SES/Generator Light On (Replace Battery/Generator)

Some customers may comment on one or more of the following conditions:

These conditions may be caused by several factors:

Caution: Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

Important: Remove the generator fuse #49, located in the under-hood fuse/relay center. This fuse should be discarded.

Test the battery with the J 42000 Battery Tester following this procedure:

1. Inspect the battery for evidence of physical damage. If damage is found, replace the battery. If no physical damage is present, proceed to the next step.
2. Is the hydrometer eye yellow? If the eye is yellow, tap the hydrometer lightly with the handle of a small screwdriver. Did the color change? If the color did not change, replace the battery. If the color did change, continue with the next step.
3. Check for loose battery cables. Attempt to rotate the battery cable end. Properly tightened battery cables will have a breakaway torque requirement of 15 N·m (10 lb ft). If the bolt is tight and the end rotates, the attaching bolt may be too long, foreign material may be lodged in the battery bolt hole, or the battery/cable end may be damaged.
4. Install the J 42000. Follow the directions supplied with the tester. When testing with the battery cables still connected to the battery, rock the J 42000 clips back and forth on the terminal bolt to cut through any coating or oxidation that may be present on the bolt. Follow the directions supplied with the tester.
5. If the battery test is OK, remove the generator fuse #49, located in the under-hood fuse/relay center. This fuse should be discarded. Recharge the battery and then perform the Charging System test below.
6. If the test result is REPLACE THE BATTERY, continue with this procedure. Remove the generator fuse #49, located in the under-hood fuse/relay center. This fuse should be discarded.
7. Disconnect both battery cables from the battery.
8. Clean the battery terminals.
9. Install the approved battery test adapters.
10. Retest the battery.
11. If the REPLACE THE BATTERY result is obtained after the second test, replace the battery and then complete the Charging System test below.

Important: For warranty purposes, always place the test code displayed by the tester from the second test on the repair order. The number is a unique identifier that describes the test data for a particular battery at a particular time. While the test code may occasionally repeat when testing the same battery, it is more likely that a different code will result each time the battery is tested.

Charging System Test

Caution: Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

Important: 

1. Make sure all electrical loads are OFF.
2. Connect J 41450-B Generator Tester to the generator. Follow the directions supplied with the tester.

If the generator fails the Charging System Test, remove the generator fuse #49, located in the under-hood fuse/relay center. This fuse should be discarded.

3. Replace the generator.

Important: This is an added circuit (circuit #840) for the 2000 model year. It is a redundant input and may be eliminated without adverse effects on the charging system integrity. 2000 model year vehicles will have three different wiring configurations. No VIN breakpoints have or will be established as the assembly plant will be using harnesses which may or may not have the latest revisions.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: