Acura / Honda transmission. Manual — part 10

Section: Acura/Honda Transmission Application

M5HA/M5DA - (1995-2005) 3.2TL, 3.5RL

M7WA/MGFA/ - (2000-06) 3.2TL, CL

MGHA - (2000-02) MDX-SUV

MDKA/BDKA - (2003-up) MDX-SUV

BAXA - (97-2002) Accord, Odyssey

MP1A - (1991-02) Prelude, Civic

M6HA - (1997-2004) Prelude, Civic

BMXA/SLXA - (2000-05) Civic

B7TA/B7YA - (1999-2000) Odyssey, Accord V-6

BYBA/BVGA - (2000-04) Odyssey, Pilot, Ridgeline

BGRA - (2005-up) Odyssey, Pilot, Ridgeline

BZKA/MZKA - (2003-up) Element

MCVA/MRVA - (2001-2004) CRV

MKYA/GPLA/MKZA/GPPA - (2004-up) CRV

4L30-E - (1996-2002) Honda-Passport, SLX

This book is based on the "Automotive Transmission Troubleshooter" software by the

same author. All similarities to this software package are intended. Both of these
products are copyrighted by the author, Mandy Concepcion. For further insight on

automotive transmissions please see our complementary DVD-Video.

Section: Acura/Honda Transmissions Component Operation

IMPORTANT FACTS ABOUT ACURA AND HONDA
TRANSMISSIONS

All HONDA/ACURA transmissions have a natural gear position. This is
the normal hydraulic fluid path when the transmission solenoids are all
OFF or without power. This is also the Limp-in Mode gear or the shift
gear that the vehicle stays in whenever there's a major fault present.
This fact automatically tells you that in the event that the trans is
stuck in limp-in mode, usually 2nd or 3rd gear, then most likely culprit
is a blown main feed fuse. Then you have to find out what caused the
fuse to burn originally. A clue to this type of fault in when the TCM or
PCM has issued a faulty code for all solenoids. This usually points to
the main fuse and a possible short circuit that caused the fuse to go
out.

So always remember that all transmissions have a natural gear when
all power is off or the main connector is disconnected. There are other
reasons why the transmission TCM is stuck in limp-in mode. This could
also be due to a faulty TPS, open solenoid, faulty TCM, or any other
electrical fault. On newer systems, the TCM is also using the WSS or
wheel speed sensor to decide when to shift the transmission.

GENERAL OPERATION and DESCRIPTION

Honda's automatic transmissions are unusual in that they do not use
planetary gears like nearly all other makers. Instead, the Hondamatic
and its successors use traditional sliding gears in parallel like a manual
transmission. Honda was forced to invent their new system due to the
vast array of patents on automatic transmission technology held by
Borg-Warner and others.

Honda initially chose to integrate the transmission and engine block for
its first application (in the N360) as in the Mini. The Hondamatic
incorporated a lockup function, which Honda called a third ratio, and
had manual gear selection. The company's early transmissions also
used a patented torque converter which used stator force rather than
hydraulic controls for shifting.

The company's naming scheme is also confusing, as it is specific to a
single model of vehicle and some identifiers are reused.

DESCRIPTION

The automatic transmission is a 3-element torque converter and a
dual-shaft electronically controlled unit which provides 4 or 5 speeds
forward and 1 reverse. The torque converter consists of a pump,
turbine and stator, assembled in a single unit. They are connected to
the engine crankshaft so they turn together as a unit as the engine
turns. Around the outside of the torque converter is a ring gear which
meshes with the starter pinion when the engine is being started. The
entire torque converter assembly serves as a flywheel while
transmitting power to the transmission main shaft. The transmission
has two parallel shafts: the main shaft and the countershaft. The main
shaft is in line with the engine crankshaft. The main shaft is also the
same as the input shaft and linked to the ISS. The main shaft includes
the 1st, 2nd and 4th clutches, gears for 2nd, 4th, reverse and 1st (3rd
gear is integral with the main shaft, while the reverse gear is integral
with the 4th gear). The countershaft includes the 3rd clutch, and gears
for 3rd, 2nd, 4th, reverse, 1st and park. The gears on the main shaft
are in constant mesh with those on the counter shaft. When certain
combinations of gears in transmission are engaged by clutches, power
is transmitted from the main shaft to the countershaft to provide [2],
[D3],[D4] and [R] positions.

Electronic Control

The electronic control system consists of the Powertrain Control
Module (PCM), sensors, a linear solenoid and four 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 on the passenger's side or under the
carpet. Often times, the TCM gets damaged by fluid or water from the
AC evaporator core or soft drinks. All shift solenoids are usually placed
on the outside, when it comes to Honda/Acura transmissions.

Hydraulic Control

The valve bodies include the main valve body, the secondary valve
body, the regulator valve body, the servo body and the lock-up valve
body through the respective separator plates.

On some units the solenoids are placed on the actual valve body. as in
other normal transmissions. Use the same repair procedures. The main
valve body contains the manual valve, the 1-2 shift valve, the 2nd
orifice control valve, the CPB (Clutch Pressure Back-up) valve, the
modulator valve, the servo control valve, the relief valve, and ATF
pump gears. The secondary valve body contains the 2-3 shift valve,
the 3-4 shift valve, the 3-4 orifice control valve, the 4th exhaust valve

and the Clutch Pressure Control (CPC) valve. The regulator valve body
contains the pressure regulator valve, the torque converter check
valve, the cooler relief valve, and the lock-up control valve. The servo
body contains the servo valve which is integrated with the reverse
shift fork, and the accumulators. The lock-up valve body contains the
lock-up shift valve and the lock-up timing valve. The linear solenoid
and the shift control solenoid valve A/B are bolted on the outside of
the transmission housing, and the lock-up control solenoid valve A/B is
bolted on the outside of the torque converter housing. Fluid from
regulator passes through the manual valve to the various control
valves. The clutches receive fluid from their respective feed pipes or
internal hydraulic circuit.

Shift Control Mechanism

Input from various sensors located throughout the car determines
which shift control solenoid valve the Powertrain Control Module (PCM)
will activate. Activating a shift control solenoid valve changes
modulator pressure, causing a shift valve to move. This pressurizes a
line to one of the clutches, engaging that clutch and its corresponding
gear. The shift control solenoid valves A and B are controlled by the
PCM.

Lock-up Mechanism

In [D4] position, in 3rd and 4th, and in [D3] position in 3rd,
pressurized fluid is drained from the back of the torque converter
through a fluid passage, causing the lock-up piston to be held against
the torque converter cover. As this takes place, the mainshaft rotates
at the same as the engine crankshaft. Together with hydraulic control,
the PCM optimizes the timing of the lock-up mechanism. The lock-up
valves control the range of lock-up according to lock-up control
solenoid valves A and B, and linear solenoid. When lock-up control
solenoid valves A and B activate, the modulator pressure changes. The
lockup control solenoid valves A and B and the linear solenoid are
controlled by the Powertrain Control Module (PCM) .

DESCRIPTION AND OPERATION

The electronic control system consists of a Powertrain Control Module
(PCM), sensors, a linear solenoid and four 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 on the passenger's side.