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DTC L202: OSM No. 2 Communications Problem: Description

Code L202 indicates that the BCM has been unable to correctly communicate information to OSM No. 2. This fault could affect the operation of the left stop/turnlamps "A" and, "B" and the left taillamps "A" and "B".

NOTE: The following numbered steps refer to circled numbers on diagnostic chart. See Fig 1. For circuit identification, see Fig 2.
  1. If you were not directed here from Lighting Chart A-1, a wrong diagnosis could result if not performed first. See LIGHTING CHART A-1 in SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  2. Visually inspect the cavities and pins of the OSM for obvious connection problems.
  3. Make sure that there is indeed power to the OSM.
  4. Checks for proper ground to the OSM.
  5. Checks for proper OSM address identification.
  6. Hazard flashers will increase data line activity. Typical voltages will be between zero and 5 volts and will be constantly changing. This will help identify whether the OSM or the data line is the problem.
NOTE: When all diagnosis and repairs are completed, clear codes and verify operation.
Fig 1: DTC L202: OSM No. 2 Communications Problem Flow Chart
G00097111Courtesy of GENERAL MOTORS CORP.
Fig 2: DTC L202: OSM No. 2 Communications Problem Flow Chart Circuit
G00097112Courtesy of GENERAL MOTORS CORP.