Isuzu KB P190. Manual - part 1008

7A2-66  TRANSMISSION CONTROL SYSTEM (AW30–40LE) 

 

Step Action  Value(s) 

YES 

NO 

8 

 

1. Reconnect all previously disconnected harness 

connector(s). 

 2. Clear the DTCs with a scan tool. 

 3. Turn “OFF” the ignition. 

 4. Start the engine. 

 

5. Operate the vehicle within the Conditions For 

Running the DTC. You may also operate the 
vehicle within the conditions that you observed 
from the Freeze Frame/ Failure Records. 

 

Did the DTC fail this ignition? 

— Go 

to 

Step 2 Go 

to 

Step 9 

9 

Observe the stored information, Capture Info with a 
scan tool. 

 

Are there any DTCs that you have not diagnosed? 

— Go 

to 

Diagnostic 

Trouble Code 

(DTC) List 

Verify repair 

TRANSMISSION CONTROL SYSTEM (AW30–40LE)  7A2-67 

 

DTC P0742 (Flash Code 53) 

 
 

 

 

 

 

 

RTW77ALF001501 

 

Circuit Description 

The lock-up solenoid SL of the torque converter clutch 
(TCC) controls the lock-up clutch by a signal according 
to the lock-up position judgment of the Transmission 
Control Module (TCM) when the vehicle runs. 
This function can improve the fuel consumption to 
almost the same extent as the manual transmission. 
The lock-up solenoid SL is put into B+ by the TCM, so
that the solenoid is actuated with the result of lock-up. 

 

Condition For Running The DTC 

All of the following conditions are met. 

 (1) All of the following conditions are met for 2 

seconds or more continuously. 

•  The supply voltage is more than 10.2 volts and 

less than 15.5 volts. 

• DTC U2104 is not detecting failure or not 

deciding failure. 

• DTC U2105 is not detecting failure or not 

deciding failure. 

•  Engine revolution signal is not detecting failure 

or not deciding failure. 

•  The engine revolution is more than 550rpm. 

7A2-68  TRANSMISSION CONTROL SYSTEM (AW30–40LE) 

 

 (2) Oil temperature is more than 20

°C (68°F), and 

water temperature signal is more than 70

°C 

(158

°F). 

 (3) 20 seconds or more passed after D position is

detected. 

  (4) Oil temperature sensor is not deciding failure. 

  (5) Engine coolant temperature sensor is not detecting

failure or not deciding failure. 

  (6) The engine revolution is more than 600 rpm. 

  (7) Engine revolution sensor is not detecting failure or

not deciding failure. 

  (8) T/F condition is high. 

 (9) T/F Hi-Low SW is not detecting failure or not

deciding failure. 

 (10) Output revolution sensor is not detecting failure or

not deciding failure. 

 (11) S1 solenoid is not detecting failure or not deciding

failure. (Electronic failure) 

 (12) S2 solenoid is not detecting failure or not deciding

failure. (Electronic failure) 

 (13) 

L-up solenoid is not detecting failure or not
deciding failure. (Electronic failure) 

 (14) Selector position switch is not detecting failure or

not deciding failure. 

 (15) DTC U2104 is not detecting failure or not deciding

failure. 

 (16) DTC U2105 is not detecting failure or not deciding

failure. 

 (17) Input revolution sensor is not deciding failure. 

 (18) 

Throttle signal is not detecting failure or not
deciding failure. 

 (19) Not emergency mode. 

 (20) Engine torque signal is not detecting failure or not

deciding failure. 

(21)  Pressure control solenoid is not detecting failure 

not deciding failure. 

(22)  All of the following conditions are met. 

•  Device Control is not operating. 

• Disable Normal Communication Service is

receiving enable. 

•  DTC Clear is not operating. 

 

Condition For Setting The DTC 

The following conditions are detected two times or more 
between ignition “ON” and ignition “OFF”. 

The TCM detects following conditions are met for 1
second continuously. 

•  2 second passed after gear change output and L-up 

“ON”/”OFF” output. 

•  T/C revolution difference more than 100 rpm for 1 

second continuously. 

•  3rd gear lock-up “OFF”. 

Action Taken When The DTC Sets 

•  No squat control. (For preventing engine stall) 

•  Fix 1st gear to prevent engine stall when vehicle 

speed is and below 10 km/h (6 mph). (Cancel at 15 
km/h {9 mph}) 

•  Check Trans “ON”. 

• DTC 

stored. 

•  MIL request “ON”. (EURO 4 only) 

Conditions For Clearing The DTC 

•  The DTC can be cleared from the TCM history by 

using a scan tool. 

•  The DTC will be cleared from history when the 

vehicle has achieved 40 warm-up cycles without a 
failure reported. 

•  After more than 1 second has elapsed after the 

ignition key has been turned “ON”, short between 
No.11 and No.4 (ground) of DLC (Data Link 
Connector). Then, after 1 second, but within 6 
seconds, discontinue shorting. 

Diagnostic Aids 

•  Inspect the wiring for poor electrical connection at the 

TCM. Look for possible bent, backed out, deformed 
or damaged terminals. Check for weak terminal 
tension as well. Also check for a chafed wire that 
could short to bare metal or other wiring.  

 

Inspect for a broken wire inside the insulation. 

•  When diagnosing for a possible intermittent short or 

open condition, move the wiring harness while 
observing test equipment for a change. 

TRANSMISSION CONTROL SYSTEM (AW30–40LE)  7A2-69 

 

Circuit/System Testing DTC P0742 

Step Action  Value(s) 

YES 

NO 

1 

 

Was the On-Board Diagnostic (OBD) System Check 
performed? 1. Install the scan tool. 

— Go 

to 

Step 2 Go 

to 

OBD 

System Check

2 

 1. Install a scan tool. 

 2. Turn “ON” the ignition. 

 3. Review and record scan tool data. 

 4. Operate the vehicle within scan tool data. 

 

Does a scan tool indicate DTC P0742? 

— Go 

to 

Step 3 Refer 

to 

Diagnostic Aids

3 

Perform the transmission fluid checking procedure. 

Refer to checking Transmission Fluid level and 
Condition in Automatic Transmission 7A section. 

If the problem found, repair or replaces necessary. 

 

Was the problem found? 

— Go 

to 

Step 8 Go 

to 

Step 4 

4 

Observe the TCC slip speed data on a scan tool. 

 1. Turn “ON” the ignition with engine “ON”. 

 2. Road testing the vehicle. 

 3. The throttle position is more than 20%. 

 4. The vehicle speed is between 5 km/h (3 mph) and 

100 km/h (62 mph). 

 5. The TCC slip speed is more than 150 rpm at 2nd 

gear L-up “OFF”. 

 6. The throttle position is more than 25%. 

 7. The vehicle speed is between 5 km/h (3 mph) and 

80 km/h (50 mph). 

 8. The T/C revolution difference is less than 100 rpm 

at 3rd L-up “OFF”. 

 

Above conditions were indicated on a scan tool 
display? 

— Refer 

to 

Diagnostic Aids 

Go to Step 5 

5 

Check the following items. 

 

• Check the L-up solenoid valve. (Refer to Section 

7A3) 

 

• L-up solenoid valve stuck “ON” the release position 

(Refer to Section 7A4) 

 

• Misaligned or damaged valve body gasket. 

 

• Restricted apply passage. 

 

If the problem found, replaces as necessary. 

 

Was the problem found? 

— Go 

to 

Step 8 Go 

to 

Step 6 

6 

Check the DTC on a scan tool. 

 

Is DTC found on a scan tool? 

— Go 

to 

Step 7 Go 

to 

Step 8