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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 1040 (Battery, Charging System And Starting System) >> Diagnostic Information and Procedures >> Charging System Test >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Generator 

  1. Verify that the battery cable terminals are clean and tight.
  2. Connect a carbon pile tester to the battery.
  3. Start the engine and increase the engine speed to 2,500 RPM. Place the vehicle in tow/haul mode. Observe the voltage reading on the tester. The voltage should read between 12.6 - 15.0 volts.
    • If not within specified range, replace the generator.
  4. Adjust the carbon pile tester to the specified load test output value, refer to Generator Usage .
    • If less than the specified value, replace the generator.
  5. If equipped with an auxiliary generator, repeat this test, with the carbon pile tester's inductive pickup clamped around either generator harness.

Auxiliary Battery Charging/Isolation (TP2) 

Perform this test if there is a concern with the charging of an auxiliary battery.

Do not perform this test if the vehicle is not equipped with an auxiliary battery (TP2).

  1. Disconnect the auxiliary battery. Refer to Auxiliary Battery Replacement (6.2L, and 6.6L) .
  2. Verify that there is not a fuse installed in the STUD 1 socket of the underhood fuse block. There may be a plastic plug installed in this position, instead of a fuse.
    • If there is a fuse installed, remove the fuse.
  3. Verify that the trailer harness, or other accessory, is connected to the underhood fuse block stud 1 terminal X7-1, if desired. Verify that the connection is clean and tight.
  4. Ignition OFF. Verify that there is 0 volts present at the underhood fuse block stud 1 terminal X7-1.
    • If there is voltage present at stud 1, test the auxiliary battery relay and the run relay for a stuck closed condition. If OK, test the auxiliary battery positive cable for a short to voltage.
  5. Start the engine. Verify that there is greater than 12 volts present at the underhood fuse block stud 1 terminal X7-1.
    • If less than the specified value, test the following components for an open/high resistance:
      • SEO B1 fuse
      • 125 A MEGA fuse
      • Fusible link 2
      • Fusible link 3
      • Auxiliary battery relay
      • Run relay
  6. Reconnect the auxiliary battery.
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