Isuzu KB P190. Manual — part 959

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–50

Action Taken When the DTC Sets

•

The TCM illuminates the MIL during the second consecutive trip in which the Conditions for Setting the DTC are
met.

•

The TCM commands maximum line pressure.

•

The TCM freezes transmission adaptive functions.

•

The TCM calculates vehicle speed from the automatic transmission engine r.p.m. and commanded gear.

•

At the time of the first failure, the TCM records the operating conditions when the conditions for setting the DTC are
met. The TCM stores this information as a Failure Record.

•

At the time of the second failure, the ECM records the operating conditions when the conditions for setting the DTC
are met. The ECM stores this information as a Freeze Frame.

•

The TCM stores DTC P0722 in TCM history.

Conditions for Clearing the DTC

•

The ECM turns off the MIL after the sixth consecutive drive trip in which the TCM does not send a MIL illumination
request.

•

Tech 2 can clear the DTC.

•

The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related
diagnostic fault occurring.

•

The TCM cancels the default actions when the ignition is off long enough to power down the TCM.

Diagnostic Aids

•

Inspect the rear internal gear teeth for damage.

•

Visually inspect the VSS for cracks or damage.

•

Ensure the VSS is properly torqued to the extension housing.

Test Description

The following numbers refer to the step numbers in the diagnostic table:

2

Disable the traction control system when performing this step. When the ignition key is cycled off and then cycled
back on, the traction control system defaults to on.

3

Checks the VSS for correct resistance.

4

Checks if the VSS and associated circuits are shorted to ground.

5

Checks the VSS produces an AC voltage when the output shaft is rotated.

6

Checks the integrity of the circuits between the TCM and the VSS.

DTC P0722 Diagnostic Table

Step Action

Yes

No

1

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to

4.7 Diagnostic

System Check

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–51

Step Action

Yes

No

2

1

Connect Tech 2 to the DLC.

2

Turn on the ignition, with the engine off.

N O T E

Before clearing the DTC, use the Tech

2 Freeze

Frame/Failure Record to record the transmission
parameters at the time the DTC set. Using Tech 2 to clear
the DTC(s) erases the Freeze Frame/Failure Record
records from the TCM.

3

On Tech 2 select:
Transmission / Automatic Transmission / Diagnostic
Trouble Codes / Freeze Frame.

4

Select the relevant DTC and note the parameters at the time of
the DTC setting.

5

On Tech 2 select:
Diagnostic Trouble Codes / Clear Engine & Transmission
DTCs.

6

Follow the instructions on Tech 2 and clear the DTCs.

7

Raise and support the rear axle assembly, refer to 0A General
Information.

8

Start the engine.

9

Disable the traction control system.

10

Place the transmission in any drive range.

11

On Tech 2 select:
Data Display / Transmission Data.

With the drive wheels rotating, does the Tech 2 AT Output Speed
parameter increase with the drive wheel speed?

Check for an

intermittent fault in

the circuit, refer to

8A Electrical-Body

and Chassis

Go to Step 3

3

1

Turn off the ignition.

2

Disconnect connector E-44 from the sensor.

3

Using a multimeter set to measure resistance, probe across the
speed sensor pins 1 and 2.

Does the multimeter display 976 – 2354

Ω?

Go to Step 4

Go to Step 6

4

1

Using a multimeter set to measure resistance, probe between
connector E-44 pin 1 and a known ground.

2

Using a multimeter set to measure resistance, probe between
connector E-44 pin 2 and a known ground.

Does the multimeter display greater than 50 k

Ω in both instances?

Go to Step 5

Go to Step 6

5

1

Place the transmission in neutral.

2

Using a multimeter set to measure AC voltage, probe across the
speed sensor pins 1 and 2.

3

Rotate a rear wheel by hand.

Does the multimeter display 0.3 V AC?

Go to Step 6

Go to Step 7

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–52

Step Action

Yes

No

6

1

Disconnect connector C-96 from the TCM.

2

Test circuits speed sensor circuits (between C-96 pin 16 and
E-44 pin 2; C-96 pin 41 and E-44 pin 1) for the following
conditions:

•

Short to ground

•

Open circuit

•

Short together

Did you find and correct the condition?

Go to Step 9

Go to Step 8

7

Replace the vehicle speed sensor, refer to 7C4 Automatic
Transmission – 4L60E – On-vehicle Service.

Did you complete the replacement?

Go to Step 9

—

8

Replace the TCM, refer to 7C4 Automatic Transmission – 4L60E –
On-vehicle Service.

Did you complete the replacement?

Go to Step 9

—

9

Perform the following procedure to verify the repair:

1

On Tech 2 select:
Diagnostic Trouble Codes / Clear Engine & Transmission
DTCs.

2

Follow the instructions on Tech 2 and clear any DTCs.

3

Operate the vehicle so the transmission output speed is greater
than 500 r.p.m. for 3 seconds.

4

On Tech 2 select:
Diagnostic Trouble Codes / Read DTC Information.

Has DTC P0722 set?

Go to Step 2

Go to Step 9

10 On Tech 2 select:

Diagnostic Trouble Codes / Read DTC Information.

Does Tech 2 display any DTCs you have not diagnosed?

Refer to

4.8 Diagnostic

Trouble Code List

System OK

When all diagnosis and repairs are completed, check the system for correct operation.

4.16 DTC P0723 – Vehicle Speed Sensor

Circuit Intermittent

DTC Description

This diagnostic procedure supports DTC P0723 Vehicle Speed Sensor Circuit Intermittent.

Circuit Description

The vehicle speed sensor (VSS) provides vehicle speed information to the transmission control module (TCM). The VSS
is a permanent magnet generator. The sensor is mounted in the extension housing facing the rear internal gear which is
splined to the output shaft assembly. As the output shaft and internal gear rotate, the toothed rotor of the internal gear
produces AC voltage as the rotor teeth pass through the magnetic field of the sensor. The AC voltage level and the
number of pulses increase as the speed of the vehicle increases. The TCM converts the voltage to vehicle speed. The
TCM uses the output shaft speed signal to determine shift timing and torque converter clutch (TCC) scheduling.

If the TCM detects an unrealistic drop in output shaft speed, DTC P0723 sets. DTC P0723 is a type B DTC.

Refer to 2

Wiring Diagrams and Connector Chart to aid in diagnosis.

Conditions for Running the DTC

•

No DTCs P0722, P1810, P1815 or P1816.

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–53

•

Ignition voltage is 8 – 18 V.

•

TFT is -40°C and 150°C.

•

The engine run time is greater than 5 seconds.

•

The throttle position is greater than 12 percent.

•

The engine torque is 108 – 882 Nm.

Conditions for Setting the DTC

The transmission output shaft speed drops greater than 1,000 r.p.m. for at least 3.4 seconds.

Action Taken When the DTC Sets

•

The TCM illuminates the MIL during the second consecutive trip in which the conditions for setting the DTC are met.

•

The TCM commands maximum line pressure.

•

The TCM freezes transmission adaptive functions.

•

The TCM calculates vehicle speed from the automatic transmission input shaft speed sensor and commanded gear.

•

At the time of the first failure, the TCM records the operating conditions when the conditions for setting the DTC are
met. The TCM stores this information as a Failure Record.

•

At the time of the second failure, the ECM records the operating conditions when the conditions for setting the DTC
are met. The ECM stores this information as a Freeze Frame.

•

The TCM stores DTC P0723 in TCM history.

Conditions for Clearing the DTC

•

The ECM turns off the MIL after the sixth consecutive drive trip in which the TCM does not send a MIL illumination
request.

•

Tech 2 can clear the DTC.

•

The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related
diagnostic fault occurring.

•

The TCM cancels the default actions when the ignition is off long enough to power down the TCM.

Diagnostic Aids

•

Inspect the rear internal gear teeth for damage.

•

Visually inspect the VSS for cracks or damage.

•

Ensure the VSS is properly torqued to the transmission housing.

Test Description

The following numbers refer to the step numbers in the diagnostic table:

2

Disable the traction control system when performing this step. When the ignition key is cycled off and then cycled
back on, the traction control system defaults to on.

3

Checks the VSS for correct resistance.

4

Checks if the VSS and associated circuits are shorted to ground.

5

Checks the VSS produces an AC voltage when the output shaft is rotated.

6

Checks the integrity of the circuits between the TCM and the VSS.