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Home >> Chevrolet >> 2000 >> Chevy Express G2500, Van Cargo Extended, 6.5 F >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - Diesel >> Circuit Tests >> Data Link Connector Diagnosis >> "G" Series

"G" Series

  1. Perform OBD system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Disconnect scan tool. Connect scan tool to another vehicle of the same year and same systems. Turn ignition on. If scan tool communicates with PCM, go to next step. If scan tool does not communicate with PCM, go to step  4.
  3. Reconnect scan tool to original vehicle. Turn ignition on. If scan tool communicates with PCM, go to step  11. If scan tool does not communicate with PCM, go to step  5.
  4. Scan tool may be faulty. Refer to scan tool instruction manual. After repairs, go to step  17.
  5. Turn ignition off. Disconnect PCM harness connectors. Measure resistance between DLC terminals No. 4 (ground circuit) and No. 2 (serial data class II circuit). If resistance is less than 10 ohms, go to next step. If resistance is not less than 10 ohms, go to step  7.
  6. Disconnect Electronic Brake Control Module (EBCM) harness connector. Measure resistance between DLC terminals No. 4 (ground circuit) and No. 2 (serial data class II circuit). Disconnect other control modules connected to serial data class II circuit, one at a time and re-measure resistance with each module disconnected. If resistance is greater than 10 ohms with any module disconnected, go to step  15. If resistance is not greater than 10 ohms with any module disconnected, go to step  14.
  7. Turn ignition on. Measure voltage between DLC terminals No. 4 (ground circuit) and No. 2 (serial data class II circuit). If voltage is less than one volt, go to next step. If voltage is not less than one volt, go to step  12.
  8. Turn ignition off. Measure resistance of serial data class II circuit between DLC and PCM harness connector terminal C8. If resistance is less than 10 ohms, go to next step. If resistance is not less than 10 ohms, go to step  13.
  9. Check for opens or shorts to ground in all power and ground circuits to PCM. Repair as necessary. After repairs, go to step  17. If all power and ground circuits are okay, go to next step.
  10. Check for poor connections at PCM. Repair as necessary. After repairs, go to step  17. If connections are okay, go to step  16.
  11. Repair intermittent short or open in serial data class II circuit. After repairs, go to step  17.
  12. Repair short to voltage in serial data class II circuit. After repairs, go to step  17.
  13. Repair open in serial data class II circuit. After repairs, go to step  17.
  14. Repair short to ground in serial data class II circuit. After repairs, go to step  17.
  15. Replace control module that caused resistance to increase. After repairs, go to step  17.
  16. Replace PCM. Perform PCM relearn procedures. See PROGRAMMING . After repairs, go to next step.
  17. Start engine and operate vehicle under conditions which original symptom was noted. If system operation is okay, perform OBD system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. If system operation is not okay, go to step  2.
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