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Isuzu KB P190. Manual - part 966

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–78

Test Description

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

Checks for a short to voltage in the 3-2 SS signal circuit.

Checks for the serviceability of the 3-2 SS.

DTC P0788 Diagnostic Table

Step Action

Yes

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to

4.7 Diagnostic

System Check

Connect Tech 2 to the DLC.

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.

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

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

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

Follow the instructions on Tech 2 and clear the DTCs.

Turn off the ignition.

Disconnect connector E-95 from the transmission.

N O T E

Additional DTCs may set

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

Turn on the ignition, with the engine off.

Using a test lamp and Tool No. J 35616-C, probe between
connector E-95 pin 11 and a known ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 3

Install Tool No. J 44152 to the transmission connector E-95.

Using a multimeter set to measure resistance, probe across
transmission connector E-95 pins 10 and 11.

Does the multimeter display less than 20

Ω?

Go to Step 4

Go to Step 6

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–79

Step Action

Yes

Remove Tool No. J44152 from the transmission.

Gain access to the 3-2 SS and the control valve body wiring
harness, refer to 7C4 Automatic Transmission – 4L60E – On-
vehicle Servicing.

Disconnect the internal connector from the 3-2 SS.

Using a multimeter set to measure resistance, probe across the
3-2 SS pins.

Does the multimeter display less than 20

Ω?

Replace the 3-2 SS,

refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing

Go to Step 7

Replace the control

valve body wiring

harness, refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing.

Go to Step 7

Using a multimeter, test between E-95 pin 11 and C-96 pin 14 for a
short to voltage.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

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

Did you complete the replacement?

Go to Step 7

—

Perform the following procedure to verify the repair:

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

Follow the instructions on Tech 2 and clear any DTCs.

On Tech 2 select:
Automatic Transmission / Data Display / Transmission Data.

Drive the vehicle in D3 or D4 and perform a 3-2 downshift.
Ensure the 3-2 Downshift Solenoid parameter displays On
when the shift occurs and Off in all other instances

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

Has DTC P0787 set?

Go to Step 2

Go to Step 8

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.

4.26 DTC P0894 – Transmission Component

Slipping

DTC Description

This diagnostic procedure supports DTC P0894 Transmission Component Slipping.

Circuit Description

The transmission control module (TCM) monitors the difference between engine speed and transmission output speed.
In D3 drive range with the TCC engaged, the engine speed should closely match the transmission output speed. In D4
drive range, with the TCC engaged, the TCC slip speed should be -20 to +50 r.p.m.

When the TCM detects excessive TCC slip when the TCC should be engaged, then DTC P0894 sets. DTC P0894 is a
type B DTC.

Refer to 2

Wiring Diagrams and Connector Chart to aid in diagnosis.

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–80

Conditions for Running the DTC

•

No DTCs P0122, P0123, P0722, P0723, P0741, P0742, P0751, P0752, P0756, P0757, P0973, P0974, P1810,
P1815, P1816, P2763 or P2764.

•

The engine speed is greater than 450 r.p.m. for 5 seconds.

•

The engine is not in fuel cut-off.

•

The engine torque is 108 Nm – 882 Nm.

•

The vehicle speed is 48 – 177 km/h.

•

The engine speed is 1,200 – 3,750 r.p.m.

•

The speed ratio is 0.70 – 2.25, speed ratio is engine speed divided by the transmission output speed.

•

The gear range is D4.

•

The commanded gear is not 1st gear.

•

The TFT is 20 – 130°C.

•

The shift solenoid performance diagnostic counters are zero.

Conditions for Setting the DTC

DTC P0894 sets if the following conditions occur for three TCC cycles.

•

The TCC is commanded on for 5 seconds.

•

The throttle position is greater than 10 percent.

•

The TCC slip speed is 100 – 550 r.p.m. for 10 seconds.

N O T E

The following actions may occur before the DTC
sets, if the:
• TCC is commanded on for 10 seconds, and
• the TCC is at 75 percent duty cycle for

5 seconds, and

• the TP angle is 10 – 99 percent, and
• the transmission slip counter has incremented

to either 1 or 2, out of 3 to increment the fail
counter for the current ignition cycle,

then the following slip conditions and actions may
increment the fail counter for the current ignition
cycle. These conditions must occur sequentially.

Condition 1

If the TCC slip speed is 100 – 550 r.p.m. for 10 seconds, then the TCM will command maximum line pressure and freeze
shift adapts from being updated.

Condition 2

If Condition 1 is met and the TCC slip speed is 100 – 550 r.p.m. for 10 seconds, then the TCM will command the TCC off
for 1.5 seconds.

Condition 3

If Condition 2 is met and the TCC slip speed is 100 – 550 r.p.m. for 10 seconds, then the fail counter on the current
ignition cycle is incremented.

The above slip conditions and actions may be disregarded if the TCC is commanded off at any time, because of a driving
manoeuvre, sudden acceleration or deceleration.

Automatic Transmission – 4L60E – Electrical Diagnosis

Page 7C2–81

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.

•

The TCM inhibits 4th gear if in hot mode.

•

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 P0894 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.

Diagnostic Aids

•

Bronze material found in the transmission oil pan may indicate stator shaft bushing wear. If bushing wear is
suspected, inspect the stator shaft and the input, turbine, shaft for damage.

•

Perform the Torque Converter Diagnosis Procedure, refer to 7C3 Automatic Transmission – 4L60E – Hydraulic and
Mechanical Diagnosis.

Test Description

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

Checks the torque converter for slippage while in a commanded lock-up state.

4-12 Checks the mechanical components that cause the DTC and their state.

When the TAP cells are cleared the TCM needs to relearn the TAP cells for the transmission. As such, when the
vehicle is first driven, the shifts may be harsh. The transmission shifts should become smoother the more the
vehicle is driven until the TCM has relearned all TAP cells.

DTC P0894 Diagnostic Table

Step Action

Yes

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to

4.7 Diagnostic

System Check

Inspect for correct transmission fluid level, refer to 7C4 Automatic
Transmission – 4L60E – On-vehicle Servicing.

Did you perform the fluid checking procedure?

Go to Step 3

Check the

transmission fluid

level, refer to

7C4 Automatic

Transmission –

4L60E – On-vehicle

Servicing

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