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Automated Manual Transmission (AMT)
Automated Manual Transmission (AMT): Driveline ratio can be tracked from input speed / output speed; mismatch between commanded gear and achieved ratio can indicate slip or a speed-sensor problem. The page also includes a worked example and measurement sequence.
Technical frame
Automated Manual Transmission (AMT): Driveline ratio can be tracked from input speed / output speed; mismatch between commanded gear and achieved ratio can indicate slip or a speed-sensor problem. The page also includes a worked example and measurement sequence.
The technical values here expose the standard, protocol or physical relationship directly; model-specific service values are linked through the matching model/variant dossier.
The goal is not only to define the term but to let the reader calculate and interpret what the data means in a scan, scope or physical test.
Concrete technical facts
- Driveline ratio can be tracked from input speed / output speed; mismatch between commanded gear and achieved ratio can indicate slip or a speed-sensor problem.
- With torque-converter lock-up applied, engine-to-turbine slip normally becomes small; the exact acceptable range is transmission/condition specific.
- In a DCT, clutch fill/adaptation values connect electronic command with actual mechanical clutch behavior.
- A CVT continuously varies input/output ratio, so a displayed “gear” should not be interpreted like a stepped planetary automatic.
- Transfer-case/differential diagnosis should consider tire circumference, wheel speeds, lubricant and mechanical preload before blaming electronics.
- Transmission temperature changes viscosity and pressure behavior, so target/actual comparisons need a comparable temperature window.
Worked example
- Ratio example: 2400 rpm input and 800 rpm output gives 3.00:1. If the controller expects 2.50:1, investigate slip, speed sensing or incorrect gear application.
Measurement and verification sequence
- Verify fluid level and temperature using the correct procedure.
- Log input/turbine/output speeds together.
- Compare commanded gear/clutch/pressure with achieved ratio/slip.
- Correlate solenoid electrical current with hydraulic pressure and mechanical response.
Fault-separation logic
- Is a valid command present and are power/ground/network healthy?
- Does feedback follow the command?
- Does an independent physical measurement confirm the output?
- Is the fault limited to a specific temperature/load/speed condition?
- Does the result remain stable when the original condition is repeated after repair?
Technical sources
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