General Transmission/Transaxle Diagnosis Flashcards

A customer says the transmission "slams" into gear only after the vehicle sits overnight. What should the technician do FIRST, before ordering parts or removing the transmission?

Answer: Verify the concern by duplicating it, then check fluid level and condition and scan for DTCs

A concern must be verified by duplicating it under the reported conditions, along with basic checks of fluid and stored codes, before any repair is chosen. Replacing parts or reflashing without verification is guessing.

A technician is checking the fluid level on a vehicle with a transmission dipstick, and the manufacturer's procedure does not specify anything unusual. Which condition is the usual requirement for the check?

Answer: Engine idling, transmission at normal operating temperature, vehicle level, selector in Park

The usual dipstick procedure is a level vehicle with the engine idling, the fluid at normal operating temperature, and the selector in Park (or as the manufacturer specifies). Reading the level under other conditions gives a false reading.

While checking fluid on a torque converter automatic, a technician finds the fluid on the dipstick is pink and milky. Which is the most likely cause?

Answer: Coolant entering the fluid through a leaking transmission cooler in the radiator

A milky, pink appearance indicates water or coolant contamination, commonly from an internal leak in the cooler inside the radiator tank. Overfill leads to foaming, not a milky color caused by coolant.

A scan tool shows DTC P0700 stored along with other transmission-related codes. What does P0700 indicate?

Answer: A request from the transmission control module to illuminate the MIL, meaning the TCM has stored its own DTCs

P0700 is the Transmission Control System Malfunction code. It means the TCM has set a fault and asked for the MIL, so the TCM's own DTCs must be retrieved to find the actual problem.

A technician retrieves DTC P0741. Which condition does this code describe?

Answer: Torque converter clutch circuit performance or stuck off

P0741 is Torque Converter Clutch Circuit Performance or Stuck Off, set when actual slip does not match what the TCC command should produce.

During a road test at a steady cruise with the TCC commanded on, a scan tool shows engine speed of 2,000 rpm and turbine speed of 1,700 rpm. What does this indicate?

Answer: About 300 rpm of converter slip, which suggests the TCC is not applying fully

Converter slip is engine speed minus turbine speed. With the TCC applied, slip should be near zero, so 300 rpm means the clutch is not holding.

A technician uses scan tool data to divide turbine (input) speed by output shaft speed while the transmission is commanded into a gear. What is the main reason for this calculation?

Answer: To compare the actual gear ratio with the expected ratio and detect internal clutch or band slippage

The input-to-output speed ratio gives the actual gear ratio, which can be compared to the specified ratio for the commanded gear. A mismatch indicates slip in an apply element.

Which test equipment is best for observing the waveform from a permanent-magnet (variable reluctance) output speed sensor, including amplitude and signal dropouts at low speed?

Answer: A digital storage oscilloscope

A DSO shows the AC waveform's amplitude, frequency, and any dropouts or noise over time, which a DMM average reading cannot show.

A technician needs to test a shift solenoid's coil with a DMM for a suspected open winding. Which procedure is correct?

Answer: Disconnect the solenoid from the circuit and measure resistance across its terminals, then compare it with the specification

Resistance must be measured with power removed and the solenoid isolated, then compared with the manufacturer's specification. An open reads infinite resistance.

A vehicle equipped with a continuously variable transmission (CVT) needs a fluid service. Which fluid should the technician use?

Answer: The CVT fluid specified by the vehicle manufacturer

A CVT depends on the fluid's specific friction characteristics for the belt or chain and pulleys, so only the specified CVT fluid should be used.