2000 Cadillac DeVille BaseFACTORY OEM SERVICE PROCEDURE

Scan Tool Does Not Communicate With Class 2 Device: Testing

  1. Connect scan tool to Data Link Connector. See Figure . If scan tool powers up, go to next step. If scan tool does not power up, go to SCAN TOOL DOES NOT POWER UP  .
  2. Turn ignition on. Attempt to communicate with each module on class 2 serial data line. If using a Tech 2, use CLASS 2 MESSAGE MONITOR feature. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any modules along class 2 serial data line, go to step  6 .
  3. Using scan tool select display DTC function for each module. If using a Tech 2, use the CLASS 2 DTC CHECK feature to determine which modules have set DTCs. Record all displayed DTCs, DTC status and module which DTC is set. If any DTCs between U1000 and U1255 are set, go to next step. If no DTCs between U1000 and U1255 are set, go to step  5 .
  4. If only DTC U1000 and U1255 are displayed, go to DTC U1000 & DTC U1255 CLASS 2 COMMUNICATION MALFUNCTION  . If DTC U1000 and U1255 are not displayed, go to DTC U1001-U1254 LOSS OF COMMUNICATIONS WITH XXX  .
  5. Go to DTC U1001-U1254 LOSS OF COMMUNICATIONS WITH XXX  and diagnose module which is not communicating. After repairs, go to BODY CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK  . If referred from another article, return to that article and perform diagnostic system check.
  6. Turn ignition off. Disconnect scan tool. Check for poor connections at DLC terminals No. 2 and 5. If connections are okay, go to next step. If faulty connections are found and repaired, go to BODY CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK  . If referred from another article, return to that article and perform diagnostic system check.
  7. Check for open in Black/White wire between DLC terminal No. 5 and ground. If circuit is okay, go to next step. If faulty circuit is found and repaired, go to BODY CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK  . If referred from another article, return to that article and perform diagnostic system check.
  8. Check for open in Purple wire between DLC terminal No. 2 and connector C200. C200 is located under left side of instrument panel near park brake pedal. If circuit is okay, go to next step. If faulty circuit is found and repaired, go to BODY CONTROL SYSTEM DIAGNOSTIC SYSTEM CHECK  . If referred from another article, return to that article and perform diagnostic system check.
  9. Turn ignition off. Disconnect splice pack SP300. SP300 is located under left side of rear seat cushion. See Figure . Turn ignition on. Attempt to communicate with any module still connected to the DLC through the class 2 serial data line. If scan tool does not communicate with any module, go to next step. If scan tool communicates with any module, go to step  11 .
  10. Turn ignition off. Disconnect splice pack SP304. SP304 is located in right rear of passenger compartment, taped to body harness, approximately 9.5" (24 cm) from cross car channel. Turn ignition on. Attempt to communicate with any module still connected to the DLC through the class 2 serial data line. If scan tool communicates with any module, go to step  34 . If scan tool does not communicate with any module, go to step  60 .
  11. Turn ignition off. Using the correct terminal adapter from terminal kit J35616-A, connect a jumper wire between splice pack SP300 Purple wire terminals "A" and "C". Turn ignition on. Attempt to communicate with Passenger's Front Door Module (PFDM). If scan tool does not communicate with PFDM, go to next step. If scan tool communicates with PFDM, go to step  17 .
  12. Turn ignition off. Remove passenger's door panel. Disconnect PFDM connectors. PFDM is located at front of passenger's door. Turn ignition on. Attempt to communicate with any module still connected to the DLC through the class 2 serial data line. If scan tool communicates with any module, go to next step. If scan tool does not communicate with any module, go to step  16 .
  13. If this is a factory armored vehicle (B05), go to next step. If this is not a factory armored vehicle, go to step  76 .
  14. Turn ignition off. Reconnect PFDM connectors. Disconnect passenger front power window switch connector. Turn ignition on. Attempt to communicate with PFDM. If scan tool does not communicate with PFDM, go to next step. If scan tool communicates with PFDM, go to step  76 .
  15. Turn ignition off. Disconnect PFDM connectors. Turn ignition on. Check for short to ground or short to voltage in Purple wire between PFDM connector C2 terminal "F" and passenger's front window switch connector terminal No. 10. See Fig 1 and Fig 2 . If circuit is okay, go to step  76 . If faulty circuit is found and repaired, go to step  78 .
  16. Turn ignition on. Check for short to ground or short to voltage in Purple wire between PFDM connector C2 terminal "F" and SP300 terminal "A". See Fig 1 . If circuit is okay, go to DIAGNOSTIC AIDS  . If faulty circuit is found and repaired, go to step  78 .
  17. Turn OFF the ignition. Disconnect jumper wire from terminal "A" (Purple wire) of splice pack SP300 and connect to terminal "B" (Purple wire). Turn ignition on. Attempt to communicate with Right Rear Door Module (RRDM). If scan tool does not communicate with RRDM, go to next step. If scan tool communicates with RRDM, go to step  19 .
  18. Turn ignition off. Remove right rear door panel. Disconnect RRDM connectors. Turn ignition on. Check for short to ground or short to voltage in Purple wire between RRDM connector C2 terminal "G" and SP300 terminal "B". See Fig 3 . If circuit is okay, go to step  76 . If faulty circuit is found and repaired, go to step  78 .
    Fig 1: Identifying Front Door Module Connectors & Terminals
    G00011702Courtesy of GENERAL MOTORS CORP.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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