Isuzu KB P190. Service manual — part 970

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–94

attaches to the control valve body within the transmission. The 1-2 SS valve receives ignition voltage through the ignition
voltage circuit. The transmission control module (TCM) controls the solenoid by providing the ground path on the 1-2 SS
valve control circuit.

When the TCM detects a continuous short to voltage in the 1-2 shift solenoid valve control circuit, then DTC P0974 sets.
DTC P0974 is a type A DTC.

Refer to 2

Wiring Diagrams and Connector Chart to aid in diagnosis.

Conditions for Running the DTC

•

The system voltage is 8 – 18 V.

•

The engine speed is 500 r.p.m. for 5 seconds.

Conditions for Setting the DTC

DTC P0974 sets if the TCM commands the solenoid on and the voltage feedback remains high, battery voltage.

Action Taken When the DTC Sets

•

The TCM requests the ECM to illuminate 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 inhibits TCC engagement.

•

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 P0974 in TCM history during the second consecutive trip in which the conditions for setting
the DTC are met.

Conditions for Clearing the DTC

•

The ECM turns off the MIL after the fourth 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 a non-emission
related diagnostic fault occurring.

•

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

Test Description

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

2

Checks the ability of the TCM to command the 1-2 SS valve.

3

Checks for a short to voltage in the 1-2 SS signal circuit.

4

Checks the serviceability of the 1-2 SS and the control valve body wiring harness.

DTC P0974 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 7C2–95

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

On Tech 2 select:
Transmission / Automatic Transmission / Miscellaneous
Tests / Shift Solenoid A.

8

With Tech 2 command the shift solenoid A ON and OFF.

9

On Tech 2 select:
Data Display / 1-2 Shift Data.

Does Tech 2 display the Shift Solenoid A Circuit as Okay?

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-95 from the transmission.

N O T E

Additional DTCs may set

3

Install Tool No. J 44152 Jumper Harness (20 pins) on to the
harness connector E-95.

4

Turn on the ignition, with the engine off.

5

Using a test lamp, probe between connector E-95 pin 4 and a
known ground.

Does the test lamp illuminate?.

Go to Step 6

Go to Step 4

4

1

Install Tool No. J44152 on to the transmission connector E-95.

2

Using a multimeter set to measure resistance, probe across
transmission connector E-95 pins 4 and 10.

Does the multimeter display less than 20

Ω?

Go to Step 5

Go to Step 7

5

1

Remove Tool No. J44152 from the transmission.

2

Gain access to the 1-2 SS and the control valve body wiring
harness, refer to 7C4 Automatic Transmission – 4L60E – On-
vehicle Servicing.

3

Disconnect the internal connector from the 1-2 SS.

4

Using a multimeter set to measure resistance, probe across the
1-2 SS pins.

Does the multimeter display less than 20

Ω?

Replace the 1-2 SS,

refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing.

Go to Step 8

Replace the control

valve body wiring

harness, refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing

Go to Step 8

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–96

Step Action

Yes

No

6

Using a multimeter, test between E-95 pin 4 and C-96 pin 2 for a short
to voltage.

Did you find and correct the condition?

Go to Step 8

Go to Step 7

7

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

Did you complete the replacement?

Go to Step 8

—

8

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

On Tech 2 select:
Data Display / 1-2 Shift Data.

4

Drive the vehicle in D4 and ensure the following conditions are
met::

•

The TCM commands the Shift Solenoid A On and the
Shift Solenoid A Circuit status parameter displays Okay.

•

The TCM commands the Shift Solenoid A Off and the
Shift Solenoid A Circuit status parameter displays Okay.

•

All conditions are met for 5 seconds.

5

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

Has DTC P0974 set?

Go to Step 2

Go to Step 9

9

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.

4.30 DTC P0976 – 2-3 Shift Solenoid Control

Circuit Low Voltage

DTC Description

This diagnostic procedure supports DTC P0976 2-3 Shift Solenoid (SS) Control Circuit Low Voltage.

Circuit Description

The 2-3 shift solenoid (SS) valve controls the fluid flow acting on the 2-3 shift valves. The solenoid is a normally-open
exhaust valve. With the 1-2 SS valve, the 2-3 SS valve allows four different shifting combinations. The solenoid attaches
to the control valve body within the transmission. The 2-3 SS valve receives voltage through the ignition voltage circuit.
The transmission control module (TCM) controls the solenoid by providing the ground path on the 2-3 SS valve control
circuit.

When the TCM detects a continuous open or short to ground in the 2-3 SS valve control circuit, then DTC P0976 sets.
DTC P0976 is a type A DTC.

Refer to 2

Wiring Diagrams and Connector Chart to aid in diagnosis.

Conditions for Running the DTC

•

The engine run time is greater than 5 seconds.

•

The 2-3 SS is commanded on.

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–97

Conditions for Setting the DTC

DTC P0976 sets when either of the following conditions occurs for 4.3 seconds:

•

The TCM detects an open in the 2-3 shift solenoid valve circuit when the 2-3 SS is commanded on.

•

The TCM detects a short to ground in the 2-3 shift solenoid valve circuit when the 2-3 SS is commanded on.

Action Taken When the DTC Sets

•

The TCM requests the ECM to illuminate the MIL.

•

The TCC commands maximum line pressure.

•

The TCM inhibits 3-2 shift if vehicle speed is less than 40 km/h.

•

The TCM freezes transmission adaptive functions.

•

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 P0976 in TCM history.

Conditions for Clearing the DTC

•

The ECM turns off the MIL after the fourth 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.

Test Description

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

4

Checks the ability of the TCM to control the solenoid.

5

Checks for supply voltage to the 2-3 SS valve.

6

Checks the ability of the TCM and wiring to control the ground circuit.

8

Checks the resistance of the control valve body wiring harness and the 2-3 SS valve.

9

Checks if the 2-3 SS or control valve body wiring harness is shorted to the transmission housing.

13

Checks if the control valve body wiring harness is shorted to ground.

14

Checks whether any of the other solenoids in the transmission are shorted to ground.

DTC P0976 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