GM Service Manual Online
For 1990-2009 cars only

Special Tools

J 42000 Battery Tester

Diagnostic Aids

Note: 

   • A dead battery is usually a symptom of another problem. Repair the problem. Do not just charge or replace the battery.
   • Failure to properly understand the battery and its function could lead to a misdiagnosis and unneeded repairs. Refer to Battery Description and Operation and Battery Common Causes of Malfunction for more information.

Follow these instructions in order to avoid an incorrect diagnosis because of connections:

    • If testing the vehicle with the battery cables still connected, wiggle the J 42000 clips on the terminal. This may cut through any coating or through any oxidation that may be present on the terminal.
    • If correct connections to the battery terminal bolts in the vehicle are in doubt, perform the following steps:
        1. Disconnect the negative battery cable.
        2. Disconnect the positive battery cable.
    • If the tester displays a "Bad Battery" result for a battery tested in the vehicle with the battery cables connected, perform the following steps:
        1. Disconnect the negative battery cable.
        2. Disconnect the positive battery cable.
        3. Replace the battery only if the Out-of-Vehicle test shows a "Bad Battery" result. This prevents battery replacements that are due only to faulty battery cable connections.

Circuit/System Testing

Warning: Refer to Battery Disconnect Warning in the Preface section.

  1. Inspect the battery for a cracked, broken, or damaged case, which may be indicated by battery acid leakage.
  2. If there is any apparent damage, replace the battery.
  3. Verify the cold cranking amperage (CCA), and reserve capacity (RC) and/or amp hour (AH) rating of the battery to the original battery or original equipment (OE) specification. Refer to Battery Usage.
  4. If the battery does not meet or exceed specifications, replace the battery.
  5. Verify that the battery cables are clean and tight. The battery terminal bolts should be torqued as specified in Fastener Tightening Specifications.
  6. If the battery cable(s) need to be cleaned, clean as required and tighten as specified.
    If the battery cable(s) are damaged, replace then tighten as specified.
  7. Install the J 42000 and follow directions supplied by the tester.
  8. If the tester calls for charging the battery, refer to Battery Charging.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Battery Positive Cable Replacement
    •  Battery Negative Cable Replacement
    •  Battery Replacement