Isuzu KB P190. Manual - part 1015

7A2-94  TRANSMISSION CONTROL SYSTEM (AW30–40LE) 

 

 

Condition For Setting The DTC 

The TCM detects following conditions for 0.5 seconds
continuously at shifting. 

•  Voltage at connector pin is 0V when solenoid is “ON”. 

(DTC P0973) 

•  Voltage at connector pin is ignition voltage when

solenoid is “OFF”. (DTC P0974) 

Action Taken When The DTC Sets 

•  No L-up control. 

•  No line pressure reduction control at gear change. 

•  No torque reduction control. 

•  No squat control. 

•  No slope control. 

•  No line pressure reduction control at garage. 

•  No input revolution sensor failure detection. 

•  No shift solenoid failure detection. 

•  No L-up solenoid failure detection. 

•  Change to emergency mode. 

•  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. 

 

Circuit/System Testing DTC P0973 or P0974 

 

Step Action  Value(s) 

YES 

NO 

1 

 

Was the On-Board Diagnostic (OBD) System Check 
performed? 

— Go 

to 

Step 2 

Go to OBD 

System Check

2 

 1. Install a scan tool. 

 2. Start the engine. 

 3. Depress the brake pedal and place the select lever 

in D position. 

 4. Press the 3rd start switch. (Turn the 3rd start 

switch “ON”.) 

 5. Press the 3rd start switch again. (Turn the 3rd start 

switch “OFF”.) 

 

Does a scan tool indicate DTC P0973 or P0974? 

— Go 

to 

Step 3 

Refer to 

Diagnostic Aids

3 

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

 2. Place the selector lever in the “P” position. 

 3. Measure the voltage between terminal C94-16 and 

terminal C94-1 (GND) on the TCM pigtail 
connector by 5-8840-0285-0 DMM. 

 

Is the voltage specified value? 

8

∼

16V Go 

to 

Step 4 

Go to Step 10

TRANSMISSION CONTROL SYSTEM (AW30–40LE)  7A2-95 

 

Step Action  Value(s) 

YES 

NO 

4 

 1. Turn “OFF” the ignition. 

 2. Disconnect the TCM connector (C-94). 

 3. Turn “ON” the ignition. 

 4. Measure the voltage between terminal C94-16 and 

terminal C94-1 by 5-8840-0285-0 DMM. 

 

Is the voltage specified value? 

0V Go 

to 

Step 5 

Go to Step 7 

5 

 1. Turn “OFF” the ignition. 

 2. Measure the resistance between terminal C94-16 

and body ground by 5-8840-0285-0 DMM. 

 

Is the resistance specified value? 

11

∼15Ω Go 

to 

Step 9 

Go to Step 6 

6 

 1. Disconnect the automatic transmission connector 

(E-54). 

 2. Measure the resistance between terminal E54-4 

and body ground by 5-8840-0285-0 DMM. 

 

Is the resistance specified value? 

11

∼15Ω Go 

to 

Step 7 

Go to Step 8 

7 

 1. Check for open or short in the wire between 

terminal C94-16 and terminal E54-4. 

 2. Repair or replace the wire between terminal C94-

16 and terminal E54-4. 

 

Is the action complete? 

— Go 

to 

Step 11 — 

8 

Replace the S1 solenoid. 

 

Is the action complete? 

— Go 

to 

Step 11 — 

9 

 1. Clear the DTC. 

 2. Perform the test-driving. 

 3. Check the DTC. 

 

Was DTC P0973 or P0974 stored? 

— Go 

to 

Step 10 

Refer to 

Diagnostic Aids

10 

Replace the TCM. 

Important: The replacement TCM must be 
programmed (Refer to SPS for procedure). 

 

Is the action complete? 

— Go 

to 

Step 11 — 

11 

 

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 12

7A2-96  TRANSMISSION CONTROL SYSTEM (AW30–40LE) 

 

Step Action  Value(s) 

YES 

NO 

12 

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)  7A2-97 

 

DTC P0976 or P0977 (Flash Code 32) 

 

 
 

 

 

RTW77ALF001501 

 

Circuit Description 

The shift solenoid S2 changes the hydraulic route with
the signals from the TCM according to the vehicle
speed and the throttle opening to control shifting. When
the shift solenoid S1 or S2 fails, the hydraulic circuit is
mechanically operated as a backup. 

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. 

 

  (2) Not emergency mode. 

  (3) 0.025 seconds or more passed after the state of 

power “ON” solenoid is changed. 

  (4) All of the following conditions are met. 

•  Device Control is not operating. 

•  Disable Normal Communication is receiving 

enable. 

•  DTC Clear is not operating.