Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 1876

7A2-120 DIAGNOSIS

Step

Action

Yes

Inspect the output signal of the speed sensor using a Tech 2 or
circuit tester.
Is the data display in the Tech 2 correct or output voltage correct
in the circuit tester?

Speed

Sensor

TCM

B13

H23

(4)

C95
(13)

E30

(2)
(1)
(3)

E10

Key SW

YEL/RED

WHT

BLK

YEL/RED

TCM terminal

Condition

B13

20km/h at L range in 1st gear

Approx. 6.2V (AC range)

Go to Step 9

Repair the defect or

replace.

Check of power supply to and earth of TCM.
Are the power supply and earth proper?

TCM

A1 (+B)

B15

H23

(15)

C95

(5)

(15)

BLK/YEL

BLK

Battery

C94

(1)

BLK

Go to Step 10

Check the power

source harness and

earth harness (bolt

tightening to the

body).

Is the stall revolution correct in D, 3, 2 and L range? Refer the
STALL TEST section in this manual.

Go to Step 11

Repair the defect or

replace.

Is the line pressure correct? Refer the LINE PRESSURE TEST
section in this manual.

Trouble in the AT

assembly or control

valve.

Repair the defect or

replace.

DIAGNOSIS 7A2-121

No. D2: Gear is Shifted Frequently

Description:

•

Gear is shifted down immediately though the accelerator pedal is stepped on a little in D, 3, 2, or L range.

Diagnosis Hints:

•

Basically, the same cause as "No. D1: Faulty gear shifting" is considered. However, as possible cause, fault

input signal of throttle position sensor or speed sensor, fault input signal of inhibitor switch, or fault of TCM

power source, earth, ground return wire are considered first.

•

Then, slip of the clutch, fault of the control valve are considered.

No. D3: Gear Shift Point is Low or High at All Point
No. D4: Gear Shift Point is Low or High at Limited Point

Description:

•

Gear shift point is deviated from the shift diagram.

•

Gear is not shifted up properly though the vehicle is accelerated.

•

Gear is not shifted immediately and enough acceleration cannot be obtained though the accelerator pedal is

stepped on.

Diagnosis Hints:

•

If the cause is not faulty gear shift, throttle position sensor disordered or fault input of speed sensor is

considered. Output signal of the throttle position sensor is changed to linear one.

(Refer the paragraph about the faulty throttle position sensor of "No. D1: Faulty gear shifting".)

No. D5: No Kick-down

Description:

•

The engine speeds up but vehicle speed does not increase when the accelerator pedal is stepped on at the

starting.

Diagnosis Hints:

•

When the gear shift is normal only without kick-down, possibility of fault of the throttle position sensor. Check

that the throttle voltage increases linearly in proportion to the throttle opening.

(Refer the paragraph about the faulty throttle position sensor of "No. D1: Faulty gear shifting".)

7A2-122 DIAGNOSIS

No. E1: No Gear Shift

Description:

•

Range is fixed without shifting the gear of 1st to 2nd, 2nd to 3rd, and 3rd to 4th.

•

Gear may be shifted or may not be shifted.

Diagnosis Hints:

•

Fixing at some gear speed, signal error from throttle position sensor or trouble in the AT main unit are supposed.

Possible Cause:

•

Slip of clutch (low clutch, high clutch and 2-4 brake).

If slip of clutch is caused, a DTC (gear ratio error) is stored.

•

Dropped line pressure.

•

Fixing at 3rd position (fail-safe activated).

Since the gear is fixed at the 3rd position because of the fail-safe function, a trouble that "No gear shift"

is resulted. In this case, the DTC is memorized.

When TCM stops operation because of faulty TCM ground, the gear is fixed at the 3rd position because

of a mechanical reason. In this case, no DTC is memorized.

••••

Incorrect properties of throttle opening signal (serial communication) of throttle position sensor.

Throttle opening signal (serial communication) of the throttle position sensor does not change in

proportion to the throttle opening. In this case, fixing at the high or low gear results in such a trouble

that "No Gear Shift".

•

Trouble in control valve body (faulty operation, sticking, clogged oil passage)

Step

Action

Yes

Gear ratio trouble diagnosis.
Travel in the following sequence for about 7 seconds or more in
each range: Start in the L range (1st) to 2 range (2nd) to 3 range
(3rd) to D range (4th) (to detect the gear ratio trouble exactly, this
process should be carried out).

Go to Step 2

Are any DTCs stored?

Go to DTC Chart

Go to Step 3

Are the quantity, contamination and smell normal?

If the ATF level is

low, replenish up to

the specified level.

Go to Step 4

If ATF is extremely

black and

contaminated and

smells burnt, slip of

the clutch is

supposed.

Overhaul the AT

unit.

DIAGNOSIS 7A2-123

Step

Action

Yes

Inspection of inhibitor switch using a Tech 2 or circuit tester.
When the select lever is operated, is the data display in the Tech
2 correct or voltage at each range correct?

Inhibitor SW

TCM

A2 (P)

A17 (3)

B2 (2)

B10 (N)

B11 (D)

B19 (R)

B21 (L)

C95

(2)

(10)

(11)

(19)

(21)

YEL/VIO

RED/BLK

BLU

BLK/GRN

Starter Relay

C94

(2)

(3)

H22

(1)

(6)

(4)

(7)

(5)

(2)

Start SW

PNK/BLU

E51

(2)

(4)

(8)

(5)

(1)

(9)

(6)

(3)

(10)

(7)

(38)

(15)

(3)

(37)

PNK/BLK

RED/YEL

YEL/VIO

BLK/GRN

PNK/BLK

RED/BLK

BLU

RED/YEL

PNK/BLU

BLK/WHT

BLK

BLK/WHT

Key Switch

WHT

Immobiliser Control Unit

TCM terminal

Range

B19

B10

B11

B17

B21

Battery
voltage

Battery

voltage

Battery
voltage

Battery

voltage

Battery
voltage

Go to Step 5

Adjust the inhibitor

switch.

Inspect the output voltage and throttle opening signal of the
throttle position sensor using a Tech 2 or circuit tester.
Is a voltage value in proportion to the throttle opening output?

TPS

TCM

A16

C56
(28)

C94
(16)

RED/WHT

C56
(49)

(38)

(57)

(69)

ECM

A47 (GND)

A35 (Output)
A26
A55 (+5V)

A69 (Idle SW)

Go to Step 6

Repair the defect or

replace.

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