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Home >> Cadillac >> 1998 >> Catera >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1740 - Torque Control Circuit >> Diagnostic Procedures (Transmission Control)
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Diagnostic Procedures (Transmission Control)

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  , then go to next step.
  2. Turn ignition off. Disconnect Transmission Control Module (TCM) harness connector. Turn ignition on, with engine off. Using DVOM, check voltage between ground and torque management request circuit at TCM harness connector. If battery voltage is present, go to next step. If battery voltage is not present, go to step 4).
  3. Using test light connected to ground, probe torque management request circuit at TCM harness connector. If test light illuminates, go to step 7). If test light does not illuminate, go to step 6).
  4. Turn ignition off. Disconnect ECM harness connector located in engine compartment relay center. Using DVOM, check harness continuity of torque management request circuit. If continuity is present, go to next step. If continuity is not present, go to step 8).
  5. Using DVOM, check harness continuity between ground and torque management request circuit. If continuity is present, go to step 9). If continuity is not present, go to step 11).
  6. Turn ignition off. Reconnect TCM harness connector. Disconnect ECM harness connector located in engine compartment relay center. Using test light connected to battery voltage, probe torque management request circuit at TCM harness connector. If test light illuminates, go to step 10). If test light does not illuminate, fault is not present. See DIAGNOSTIC AIDS.
  7. Repair short to voltage in request circuit. After repairs, go to step 13).
  8. Repair open or high resistance in request circuit. After repairs, go to step 13).
  9. Repair short to ground in request circuit. After repairs, go to step 13).
  10. Replace TCM. After replacing TCM, go to step 13).
  11. Check for poor connections and terminal tension at ECM harness connector. Repair as necessary. After repairs, go to step 13). If connections and terminals are okay, go to next step.
  12. Replace ECM. NEW ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
  13. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P1740 is set, go to step 2). If DTC P1740 is not set, go to next step.
  14. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.
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