For a complete wiring diagram Refer to Section 8W.This DTC is not stored alone. It is stored if a Gear Ratio DTC is detected immediately after shift. The existence of DTC P1790 indicates a mechanical or hydraulic (not electrical) related problems. It should be noted, however, that all mechanical problems don't necessarily result in DTC P1790. When this DTC exists, diagnosing the system should be based on the associated DTC and only mechanical causes should be considered.When Monitored:After a Gear Ratio Error code is stored.Set Condition:After a Gear Ratio Error DTC has already been set. The DTC is set if the fault happened within 1.3 seconds of a shift. The DTC set time will vary from 1.214 seconds to 15 seconds.Possible CausesFAULT AFTER SHIFTAlways perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE) 1. FAULT AFTER SHIFTThis DTC is set along with a Gear Ratio DTC. Perform the appropriate test for the Gear Ratio DTC stored.Check Pending DTCs or 1 trip failures if there are no Active or Stored Gear Ratio DTCs.If there are no possible causes remaining, view repair.RepairRefer to the Transmission category and perform the appropriate symptom.Perform 42RLE TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)