Trace the difference between the gear requested by a controller, electrical solenoid states, hydraulic valve position, clutch pressure, and the gear ratio measured at the shafts.
A valid solenoid command is not proof of solenoid current. Current is not proof that a valve moved. Valve movement is not proof that the clutch applied. Choose independent tests to isolate which link in the chain failed.
Illustrative teaching model—not a real valve body or OEM shift chart. This fictional four-speed unit uses two binary shift-solenoid states to select a hydraulic route, then models two holding elements per gear. Real transmissions vary in solenoid naming, energize-to-apply logic, clutch combinations, fail-safe behavior, pressure controls and gear ratios. The simple speed-ratio display assumes a fully released torque-converter clutch is outside the measurement path; use transmission input/turbine speed, not engine speed. Consult OEM data and safety procedures before hands-on testing.
0 / 5 challenge tickets solvedThe underlying fault is hidden. Select a ticket, explore the required range and run checks.
F = forward clutch; L = low reaction element; I = intermediate element; D = direct element; O = overdrive element. These labels are invented teaching shorthand—not OEM components or a real clutch chart.
| Gear | A command | B command | Teaching element pair | Ideal input:output |
|---|
ON/OFF means the commanded electrical energization state in this fictional circuit. Actual selector-valve position can differ when electrical or mechanical faults occur.
Choose a mystery ticket, collect evidence, and defend a diagnosis.