GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Blazer - 4WD - RHD 🢒 Body and Accessories 🢒 Data Link Communications 🢒 Data Link Communications System Check
  1. Inspect for the proper connection of the scan tool to the Data Link Connector (DLC).
  2. Inspect for loose or missing terminals at the DLC.
  3. If the Vehicle Control Module (VCM) is not accessible with a scan tool, inspect for an open in CKT 1807 (PPL) between the component and splice 201 (S201).
  4. If the Electronic Brake Control Module (EBCM) is not accessible with a scan tool, inspect for an open in CKT 1807 (PPL) between the component and splice 201 (S201).
  5. If the Body Control Module (BCM) is not accessible with a scan tool, inspect for an open in CKT 1807 (PPL) between the component and splice 201 (S201).
  6. If the Instrument Cluster is not accessible with a scan tool, inspect for an open in CKT 1807 (PPL) between the component and splice 201 (S201).
  7. If the Transfer Case Control Module (TCCM) is not accessible with a scan tool, inspect for an open in CKT 1807 (PPL) between the component and splice 201 (S201).
  8. If the Electronic Climate Control (ECC) Module is not accessible with a scan tool, inspect for an open in CKT 1807 (PPL) between the component and splice 201 (S210).
  9. If the Memory Seat Module is not accessible with the scan tool, inspect for an open in CKT 1807 (PPL) between the component and splice 201 (S201).
  10. If the scan tool will not communicate with any module on the Class 2 data line, inspect for an open in CKT 1807 (PPL) between splice 201 (S201) and DLC terminal  2.
  11. If the Inflatable Restraint Sensing and Diagnostic Module (SDM) is not accessible with a scan tool, inspect for an open in CKT 800 (TAN) between the component and the DLC terminal 9.
  12. Inspect for a broken, or partially broken, wire inside of the insulation. A broken, or partially broken wire could cause the system to malfunction but prove good in a continuity/voltage test with the system disconnected. The circuits may be intermittent or resistive when loaded. If possible, inspect the circuits by monitoring for a voltage drop with the system in operation (under load).
  13. Inspect for the proper installation of any aftermarket electronic equipment which may affect the integrity of the other systems.