in line with the engine crankshaft, and includes the 4th and 5th clutches, and gears for 5th, 4th, reverse, and
idler. The mainshaft reverse gear is integral with the mainshaft 4th gear. The countershaft includes the gears for
1st, 2nd, 3rd, 4th, 5th, reverse, park, and the final drive. The final drive gear is integral with the countershaft.
The countershaft 4th gear and the countershaft reverse gear can be locked to the countershaft providing the 4th
or reverse gear, depending on which way the selector is moved. The secondary shaft includes the 1st, 2nd, and
3rd clutches, and gears for 1st, 2nd, 3rd, and idler. The idler shaft is located between the mainshaft and
secondary shaft, and the idler gear transmits power between the mainshaft and the secondary shaft. The gears on
the mainshaft and the secondary shaft are in constant mesh with those on the countershaft. When certain
combinations of gears in the transmission are engaged by the clutches, power is transmitted through the
mainshaft, then to the secondary shaft to the countershaft provide drive.
ELECTRONIC CONTROL
The electronic control system consists of the powertrain control module (PCM), sensors, and solenoid valves.
Shifting and lock-up are electronically controlled for comfortable driving under all conditions. The PCM is
located below the dashboard, under the front lower panel behind the center console.
HYDRAULIC CONTROL
The valve bodies include the main valve body, the regulator valve body, and the servo body. They are bolted to
the torque converter housing. The main valve body contains the manual valve, the shift valves A, B, C, and E,
the relief valve, the lock-up control valve, the cooler check valve, the servo control valve, and the ATF pump
gears. The regulator valve body contains the regulator valve, the torque converter check valve, lock-up shift
valve, and the 1st and 3rd accumulators. The servo body contains the servo valve, the shift valve D,
accumulators for 2nd, 4th, and 5th, and shift solenoid valves for A, B, C, D, and E. Fluid from the regulator
passes through the manual valve to the various control valves. The 1st, 3rd, and 5th clutches receive fluid from
their respective feed pipes, and the 2nd and the 4th clutches receive fluid from the internal hydraulic circuit.
SHIFT CONTROL MECHANISM
The PCM controls to shift gears the shift solenoid valves A, B, C, D, and E, and the A/T clutch pressure control
solenoid valves A, B, and C, while receiving input signals from various sensors and switches located throughout
the vehicle. The shift solenoid valves shift the positions of the shift valves to switch the port leading hydraulic
pressure to the clutch. The A/T clutch pressure control solenoid valves A, B, and C regulate their respective
pressure, and pressurize to the clutches to engage it and its corresponding gear. The pressures of the A/T clutch
pressure control solenoid valves also apply to the shift valves to switch the port.
LOCK-UP MECHANISM
The lock-up mechanism operates in D position (2nd, 3rd, 4th, and 5th), in D
3
position (2nd and 3rd), and M
(sequential sportshift mode) position (3rd, 4th, and 5th). The pressurized fluid is drained from the back of the
torque converter through a fluid passage, causing the torque converter clutch piston to be held against the torque
converter cover. As this takes place, the mainshaft rotates at the same speed as the engine crankshaft. Together
with the hydraulic control, the PCM optimizes the timing and volume of the lock-up mechanism. When the shift
solenoid valve E is turned on by the PCM, shift solenoid valve E pressure switches the lock-up shift valve lock-
up on and off. The A/T clutch pressure control solenoid valve A and the lock-up control valve control the
volume of the lock-up conditions.
2004 Acura TSX
2004 AUTOMATIC TRANSMISSIONS Diagnosis - MCTA 5-Speed