Detailed description of CVT Transmission (continuous variable transmission) training seminar.
This seminar will provide you with an in depth explanation of how the CVT transmission works. It also provides you with the beautiful skill to diagnose a faulty CVT.
Many late model vehicles have CVT transmissions, the ECS help desk is flooded with calls were the diagnostician is not sure if the problem is in the CVT trans, or in the fault is in the engine. Many CVT's get condemned, rebuild, refitted for the problem to still be there. You will be toaught how to determine conclusively where the fault actually is with out the endless arguments between the transmission rebuilder and the workshop fitting the CVT.
The diagnostic methodology can also be used for other types of transmissions. Please refer to our flow diagram where this seminar fits in our proposed study path.
The following topics are covered in depth:
- A brief over view of the roots of the CVT.
- Advantages over 'normal' transmissions.
CVT Core pricipals
- Ratio adjustment.
- Push belt construction and common failures.
- What is the end goal in measuring. The first measurement shows what we are going to achieve, the whole course is to build up towards being able to measure and understanding this recording.
Mechanical movement Pulleys
- How do the pulley diameters get adjusted mechanically and hydraulically.
- constructions and oil supply for lock up and non lock up state.
Forward reverse gear set
- The mechanical and hydraulic operation of this one planetary gear set.
- Hydraulic diagrams of valve bodies will be used to understand which electronic controlled solenoid activated which slide in the valve body, to ultemately see which solenoid affects which part of the CVT.
Gear ratio control
- How does the ECU control the gear ratio with the solenoids, through the valve body, towards both the pulleys.
Pulley speed sensors
- Measuring with a scope and scan tool Live data.
- Convert speed sensor signals into RPM traces.
- Combine RPM traces to live ratio traces.
Pulley pressure control valve diagnostics
- Measure the pressure control valves signals with a scope and scantool, to see the 'effort' the ECU is doing trying to modify the ratio with hydraulis pressure.
Ratio control errors
- Looking at common faults in CVT transmissions where the ratio is controlled incorrectly or where the ratio 'leads its own life'.
Mis diagnosed CVTs
- A number of study cases will be dealt with were the CVT was incorrectly diagnosed as being faulty.
- Service intervals, Fluid properties, CVT sensor calibration after service and repair.
The diagnostician can bring his/her own scope, or our high speed dual channel scopes (ATS) can be used.
Pre requisite: From our experience we advise that the diagnostician has completed the AED 'Automotive Electronic Diagnostic' 2 day training seminar, regardless achieved level through other training systems or experience.
After Rohit from Ashburton Toyota attended the CVT11 training seminar in Palmerston North (29 10 2015). Rohit wrote as comment in the evaluation form that as most value to him was: "how did the CVT works problems and diagnostic."