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Home >> Chevrolet >> 2004 >> Impala LS >> Repair and Diagnosis >> External Pages >> Different car >> Section 326 (Computer/Integrating Systems) >> Diagnostic Information and Procedures >> DTC U2099 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2006 Buick Lucerne. However, it is still accessible from the selected car via links, so may be relevant.
  1. With the ignition OFF, disconnect the harness connector at the EBCM and ESC module one at a time. After each disconnect, clear the DTC, cycle the ignition key 3 times, then retest for the DTC. DTC U2099 should reset.
    • If the DTC does not reset, replace the last module disconnected.
  2. Ignition OFF, disconnect the harness connector at the BCM.
  3. With all modules disconnected, test for infinite resistance between the high speed GMLAN serial data wake up circuit and ground.
    • If less than infinite resistance, repair the wake up circuit for a short to ground.
  4. If all tests normal and DTC is current, replace the BCM.
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