Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 652
7A1–108 AUTOMATIC TRANSMISSION (4L30-E)
DIAGNOSTIC TROUBLE CODE (DTC) 44
BAND APPLY SOLENOID SHORT TO PLUS
This DTC flashes the CHECK TRANS indicator and
sets the BACKUP MODE.
Circuit Description:
•
The band apply solenoid is a normally open
solenoid which controls the flow of fluid for brake
band application. The Transmission Control
Module (TCM) uses Pulse Width Modulation
(PWM) and changes the duty cycle to control the
solenoid. The TCM turns the solenoid ON
(energized) and OFF (de-energized) at a constant
frequency. The length of time the solenoid is
energized during each ON/OFF cycle is called the
pulse width. By varying or “modulating” the
pulse width, the solenoid output pressure is
changed. Since the solenoid is normally closed,
increasing the pulse width increases the duty
cycle and decreases the output pressure. PWM
control provides smooth band application
without an accumulator. The band is only applied
in first and second gears.
•
In the event of an electrical failure (open), the
solenoid regulates at the maximum oil flow (0%
duty cycle).
•
The solenoid is activated by a current. This
current is produced by applying a voltage to one
side (the High side) and a ground to the other
side (Low side).
•
The High Side Driver (HSD) is a circuit of the TCM
that acts as a switch between the solenoids and
the supply voltage. The High side of the solenoid
is permanently supplied with voltage, except in
BACKUP MODE or when ignition is OFF the HSD
is turned OFF.
•
The TCM continually monitors the solenoid
connection to its Low Side Driver (LSD) for either
low or high voltage. The LSD is a circuit of the
TCM that acts as a switch between the solenoid
and ground. When the solenoid is commanded
ON the TCM is switching the solenoid to ground.
•
There are two tests of the LSD: when the engine
is cranked (DTC82) and when the ignition is
turned ON (DTC44).
•
When the ignition is turned ON, and before the
engine is cranked, the TCM activates the shift
solenoids (A, B and Band) to check for short
circuits or open circuits. To do so the gear is set
to 4th, 3rd, 1st, 1st with band apply, 4th with no
HSD. Each one of the 5 tests requires 0.15
second. If the engine is cranked before the end of
all tests, the remaining tests are not done.
Diagnostic Aids:
•
This diagnostic is an electrical test done by the
TCM.
•
Detection conditions:
1 The solenoid Low side connected to TCM
terminal A9 is shorted to voltage.
2 The test is only done when ignition is ON.
3 Engine Speed < 480 RPM (not cranked) and
Output Speed = 0 RPM.
4 The condition needs to be present for 0.15 to
1.18 second after ignition switch ON.
•
Action after the detection time: BACKUP MODE.
•
Recovery conditions: To recover, do an IGNITION
CYCLE.
TRANSMISSION
CONTROL
MODULE (TCM)
SHIFT
SOLENOID
A
SHIFT
SOLENOID
B
BAND
APPLY
SOLENOID
AUTOMATIC
TRANSMISSION
M-7
3(D)
4(C)
BRN/WHT
YEL/GRN
YEL/GRN
1(A)
BRN/BLK
H-23
H-23
YEL/BLK
YEL/BLK
2(B)
M-7
C12(12)
14
A2(2)
A3(3)
A9(9)
13
6
16
SHIFT &
BAND APPLY
SOLENOID
CONTROL
C-95
RED/BLU
RED/BLU
GRN
A7(7)
A4(4)
BATTERY
ECM MAIN RELAY
BATTERY
INPUT
IGNITION
INPUT
C-96
GROUND
BRN/WHT
BRN/BLK
D07LW018