Isuzu KB P190. Service manual — part 969

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–90

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 1-2 SS is commanded on.

Conditions for Setting the DTC

DTC P0973 sets when either of the following conditions occurs for 4.3 seconds:

•

The TCM detects an open in the 1-2 shift solenoid valve circuit when the 1-2 SS is commanded on.

•

The TCM detects a short to ground in the 1-2 shift solenoid valve circuit when the 1-2 SS is commanded on.

Action Taken When the DTC Sets

•

The TCM requests the ECM to illuminate the MIL during the second consecutive drive trip in which the conditions
for setting the DTC are met.

•

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 P0973 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 1-2 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 1-2 SS valve.

9

Checks if the 1-2 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 if any of the other solenoids in the transmission are shorted to ground.

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–91

DTC P0973 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

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.

Are any of the following DTCs also set?

•

P0787

•

P0976

•

P2764

•

P2769.

Go to Step 3

Go to Step 4

3

Inspect fuse C-8 and check if it is blown, refer to 8A Electrical-Body
and Chassis.

Is the fuse blown?

Replace the fuse

Go to Step 12

Go to Step 5

4

1

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

2

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

3

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 5

5

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 10 and a
known ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 15

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–92

Step Action

Yes

No

6

1

Using a test lamp, probe connector E-95 pin 10 with the ground
lead to connector E-95 pin 4.

2

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

3

With Tech 2 command the shift solenoid A On and Off three
times.

Does the test lamp turn on and off with each command?

Go to Step 8

Go to Step 7

7

Is the test lamp always illuminated?

Go to Step 16

Go to Step 17

8

1

Remove Tool No. J44152 from the harness connector
E-95 and install on to the transmission connector
E-95.

2

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

Does the multimeter display 19 – 31

Ω?

Go to Step 9

Go to Step 10

9

Using a multimeter set to measure resistance, probe between:

•

Transmission connector E-95 pin 10 and a known ground.

•

Transmission connector E-95 pin 4 and a known ground.

Does the multimeter display greater than 250 k

Ω in both instances?

Check for an

intermittent fault in

the circuit, refer to

8A Electrical-Body

and Chassis

Go to Step 11

10 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 19 – 31

Ω?

Replace the control

valve body wiring

harness, refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing

Go to Step 19

Replace the 1-2 SS,

refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing.

Go to Step 19

11 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

Using a multimeter set to measure resistance, probe between
each of the 1-2 SS pins and a known ground.

Does the multimeter display 250 k

Ω in both instances?

Replace the control

valve body wiring

harness, refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing

Go to Step 19

Replace the 1-2 SS,

refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing.

Go to Step 19

12 Using a multimeter, test between E-95 pin 10 and C-107 pin 9 for a

short to ground.

Did you find and correct the condition?

Go to Step 19

Go to Step 13

13 1

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

2

Test for a short to ground in the control valve body wiring
harness.

Did you find a short to ground condition?

Replace the control

valve body wiring

harness, refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing

Go to Step 19

Go to Step 14

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–93

Step Action

Yes

No

14 1

Test each solenoid for a short to ground.

2

Replace the faulty solenoid as necessary.

Did you complete the replacement?

Go to Step 19

—

15 Using a multimeter, test between E-95 pin 10 and C-107 pin 9 for an

open circuit.

Did you find and correct the condition?

Go to Step 19

—

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

to ground.

Did you find and correct the condition?

Go to Step 19

Go to Step 18

17 Using a multimeter, test between E-95 pin 4 and C-96 pin 2 for an

open circuit.

Did you find and correct the condition?

Go to Step 19

Go to Step 18

18 Replace the TCM, refer to 7C4 Automatic Transmission – 4L60E –

On-vehicle Servicing.

Did you complete the replacement?

Go to Step 19

—

19 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 P0973 set?

Go to Step 2

Go to Step 20

20 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.

4.29 DTC P0974 – 1-2 Shift Solenoid Control

Circuit High Voltage

DTC Description

This diagnostic procedure supports DTC P0974 1-2 Shift Solenoid (SS) Control Circuit High Voltage.

Circuit Description

The 1-2 shift solenoid (SS) valve controls the fluid flow acting on the 1-2 and 3-4 shift valves. The solenoid is a normally-
open exhaust valve. With the 2-3 SS valve, the 1-2 SS valve allows four different shifting combinations. The solenoid