Isuzu Trooper (1998-2002 year). Manual

7A–42

AUTOMATIC TRANSMISSION (AW30-40LE)

DTC P0748 (FLASHING CODE 35) PRESSURE CONTROL SOLENOID FAILURE (STH)

D07RY00047

Circuit description:
The pressure control solenoid is a PWM duty control
solenoid located in the valve body.
The pressure control solenoid is a TCM-controled device
used to regulate transmission throttle pressure by
energizing current from the TCM.

Fail-safe control:
The TCM controls fail-safe by detecting pressure control
solenoid failure.

Failure detection:
IG short failure

• When the feedback A/D value is more than 1020 for

500 milli-second continuously.

• Detection inhibit condition: Prohibition during 1 second

after reversion from open failure, because the
possibility of the mis-detection is high.

Open failure (Including GND Short)

• When the feedback A/D value is less than 15 for more

than 70 milli-second continuously, judges as faliure,
and turns the current of target output off, after 1.5
second passed turns the current of target value to
normal. The A/D value is checked, and this operation
is repeated during 70 milli-second again.

• When it continues for 12.5 second in total.

Contents of control:
At failure detection

• Lock-up control inhibit

• Up hill and down hill control inhibit

• Squat control inhibit

At failure decision

Executes following items in addition to above control
items at failure detection.

•Turns Solenoid power supply OFF

• Blinks "CHECK TRANS" lamp

• Stores the failure information in failure memory

* Prohibits failure detection of S1, S2, SL, STH, selector

position switch, and oil temperature sensor.

Conditions of turning "CHECK TRANS" off:
Turns "CHECK TRANS" lamp off after ignition is turned
ON

→

OFF

→

ON.

Reversion conditions from fail-safe:
At failure detection

When IG short failure···The feedback A/D value is
less than 1020 for 1 second continuously.
When open failure···Detection criteria is not satisfied
or the feedback A/D value is more than 15 for 1
second continuously.

At failure decision

Recovers at the same time as the conditions of
turning “CHECK TRANS” lamp off are satisfied.

Test description:

The following numbers correspond to circled numbers on
the diagnostic chart.

(1) The solenoid resistance is within the range of 5 to

5.6

Ω

(2) This test checks for shorted circuit at the TCM.

Diagnostic aids:
An intermittent may be caused by a poor connection,
rubbed through wire insulation or a wire broken inside
the insulation. Inspect related harness connector for
backed out terminals, improper mating, broken locks,
improperly formed or damaged terminals, poor terminal
to wire connection and damaged harness.

7A–44

AUTOMATIC TRANSMISSION (AW30-40LE)

DTC P0753 (FLASHING CODE 31) SOLENOID 1 FAILURE (S1)

D07RY00047

Circuit description:
The shift solenoid S1 changes the hydraulic route with
the signals from the TCM according to the vehicle speed
and the throttle opening to control shifting. When the
solenoid S1 or S2 fails, the hydraulic circuit is
mechanically operated as a backup.

Fail-safe control:

The TCM controls fail-safe by detecting S1, S2 shift
solenoid failure.

Failure detection:
GND SHORT detection

• When SHORT detection continues for 0.3 sec.

• When SHORT failure detection continues 8 times.

Open detection

• When OPEN detection continues for 0.5 sec.

• When OPEN failure detection continues 8 times.

Contents of control:
At failure detection

• Lock-up control inhibit

• Up hill and down hill control inhibit

• Squat control inhibit

Isuzu Trooper (1998-2002 year). Manual - part 711