02-8
1. OVERVIEW
Engine power reaches the transaxle via a torque converter with integral converter lock-up clutch. The six
forward gears and one reverse gear are obtained from a single planetary set, followed by a double
planetary set. This type of gear-set arrangement is commonly known as Lepelletier type gear-set.
The Model M11 6 speed automatic transaxle is electronically controlled. The control system is
comprised of the following components:
External transaxle control unit (TCU)
Internal embedded memory module (EMM)
Input and output speed sensors
Valve body unit comprised of four ON/OFF solenoid valves and six variable bleed solenoids (VBS)
Torque converter -
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TCU controls the oil pressure for various internal clutches and bands to select the gear. It also controls
the electronic elements, shift pressure and torque converter slip. If the system is defective, TCU provides
FMEC (Failure Mode Effect Control) to maintain the functionality of transaxle. This keeps the basic
function of transaxle (gear selection) even when there are failure in controls and power supply.
There are selector shaft position sensor (inhibitor switch) and oil temperature sensor in transaxle. In
manual mode, TCU receives the information from TGS (Transmission Gear Selector) through PCB
(Printed Circuit Board) when driver selects the manual shift mode. TCU communicates with other
electric control modules through CAN. In order to ensure a safe driving state and to prevent damage to
the automatic transmission, TCU switches to Limp-Home mode in the event of critical faults.
02-153680-01
This information is used by the TCU to decide which shift pattern to select and for shift energy
management. Electro-hydraulic solenoid valves and variable bleed solenoids control the transaxle gear
changes.
Six variable bleed solenoids and four on/off solenoids are used to direct transaxle fluid flow to control the
fluid pressure within the three clutches and two bands. Separate pressure regulators are used
exclusively for torque converter clutch control and main transaxle line pressure.
The TCU monitors all TCU inputs and outputs to confirm correct system operation. If a fault occurs the
TCU is able to perform default action and inform the driver of the problem through the instrument cluster
warning lights. Detailed information is available via trouble codes which can be read with the service tool.
11-210000-00
Circuit description ▶
When compared to the vehicle equipped with ABS/EBD only, the internal hydraulic circuit has a
normally-open separation valve and a shuttle valve in primary circuit and in secondary circuit.
When the vehicle brakes are not applied during engine running or when applying the non-ABS operating
brakes, the normally-open separation valve and the inlet valve are open, whereas the normally-closed
shuttle valve and the outlet valve are closed.
When the ESP system is operating, the normally-open separation valve will be closed by the solenoid
valve operation and the hydraulic circuit will be established by the shuttle valve. Then, the inlet and outlet
valves will be closed or open depending on the braking pressure RISE, HOLD or DUMP conditions.
Flashing warning lamp and warning sound during ESP operation ▶
When the ESP operates while the vehicle is moving, the ESP warning lamp on the instrument panel
flickers and the buzzer sounds at every 0.1 second. The ESP lamp operation is to inform a driver that the
vehicle is extremely unstable.
The ESP system is just a supplementary system for the vehicle and it cannot control the vehicle over the
physical limit. Do not solely rely on the system but be advised to drive the vehicle safely.
Drive feeling during ESP operation ▶
When the ESP system activates, the driving feeling can be different depending on vehicle driving
conditions. For example, it will feel different when the ESP system is activated while the ABS is operated
by depressing the brake pedal and when the ESP system is in control without the brake pedal
depressed on the same curve.
If the ESP system operates with the brake applied, the brake pressure will be increased on the
corresponding wheel which already has braking pressure for the ESP controls. In other words, the ESP
system would make the driver feel more abruptly braked compared to the situation that the braking
pressure is applied to wheel which had no braking force.
Noise and vibration that driver senses during ESP operation ▶
The ESP system may transfer noise and vibration to a driver due to the pressure changes caused by the
motor and valve operations in a very short period of time.
Extreme cornering will trigger the ESP operation and this will make the driver sense noise and vibration
due to sudden brake application.
Also, the ESP system controls the engine power. Therefore, the driver may notice the engine power
decreases even when the accelerator pedal is depressed.
