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Home >> Cadillac >> 2000 >> DeVille Base >> Repair and Diagnosis >> Body & Frame >> Windows >> Power Window System >> Diagnostic Tests >> DTC U1161: Loss Of PDM Serial Data, DTC U1162: Loss Of LRDM Serial Data, DTC U1163: Loss Of RRDM Serial Data Or DTC U1170: Loss Of Driver's Door Switch Assembly Serial Data >> Diagnostic Procedure
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Diagnostic Procedure

  1. Connect scan tool. Turn ignition switch to ON position. If DTCs U1161, U1162, U1163 and U1170 have a current status, go to step  5 . If DTCs U1161, U1162, U1163 and U1170 do not all have a current status, go to next step.
  2. If DTCs U1161, U1162 and U1163 have current status, but not U1170, go to next step. If DTCs U1161, U1162 and U1163 do not all have current status, go to step  4 .
  3. Test wiring and connections between Drivers Door Module (DDM) and all other door modules. See WIRING DIAGRAMS  . If problem was found, repair as necessary, and then retest system. If problem was not found, replace DDM.
  4. Test battery feed circuit, ground circuit and simple serial bus circuit at door module that is not functioning. See WIRING DIAGRAMS  . If problem was found, repair as necessary, and then retest system. If problem was not found, replace door module.
  5. Disconnect Drivers Door Module (DDM) and Drivers Door Switch Assembly (DDSA). Check simple bus serial circuit between DDM and DDSA. See WIRING DIAGRAMS  . If problem was found, repair as necessary, and then retest system. If problem was not found, go to next step.
  6. Disconnect all other door modules. Turn ignition switch to ON position. Check for short to ground or short to power in simple serial bus circuit. See WIRING DIAGRAMS  . If problem was found, repair as necessary, and then retest system. If problem was not found, go to next step.
  7. Turn ignition switch to OFF position. Reconnect DDM. Turn ignition switch to ON position. Using scan tool, operate driver door window and lock. If window and lock operate, go to next step. If window and lock do not operate, replace DDM.
  8. Turn ignition switch to OFF position. Connect DDSA. Turn ignition switch to ON position. Operate driver door window and lock with DDSA. If window and lock operate, go to next step. If window and lock do not operate, replace DDSA.
  9. For each passenger door: Turn ignition switch to OFF position. Connect door module. Turn ignition switch to ON position. Verify window works from switch on door. Operate window from driver door switch. If window operates, go to next door. If window does not operate, connect scan tool and read DTCs from DDM. If "U" code for that door is present, replace door module. If "U" code for that door is not present, replace DDM.
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