3.5.7.8 P0603 P0604 P1604 P1701 P1703 

1. DTC 

description: 

DTC P0603 

TCU Self-learning data memory error 

 

DTC P0604 

Reach to TCU self-learning data limit 

 

DTC P1604 

TCU EMM data error 

 

DTC P1701 

TCU power supply voltage is low 

 

DTC P1703 

TCU power supply voltage is high 

The transmission control unit (TCU) controls the transmission through the variable flow electromagnetic valve 
and switching electromagnetic valve. The transmission control unit operates under a voltage ranging from 8 to 
16V and usually consumes less than 4A current and needs to change gear when the current consumption reaches 
10A. 

If the transmission element is worn to a certain extent, the transmission control unit TCU can compensate these 
differences within the range of the service life of the transmission through self-learning function, thereby ensuring 
the shift quality. However, in case the parts in the transmission are worn to a certain point, the gear shifting 
quality can not be ensured no matter how the transmission control unit (TCU) teaches oneself; and at this tie, the 
transmission control unit (TCU) shall report a fault code. 

2.  Conditions for setting DTC and the gault position: 

DTC code 

DTC detection strategy 

Conditions for setting the DTC 

(control strategy) 

Fault positions 

P0603 

Detect hard part circuit 

P0604 

Detect hard part circuit 

P1604 

EMM digital image stored in 

the TCU was damaged and 

lost 

Ignition switch is in ON position 

P1701 

System pressure is less than 

work voltage of 

electromagnetic valve 

1.  ignition switch is in the opening 

position 

2.  Engine speed >300 r/min 

3.  Transmission control unit power 

supply voltage <8 V for 0.5 s 

1. TCU 

2.  TCU power supply 

circuit 

3. TCUgrounding 

circuit 

1283

 
 

P1703 

System voltage is higher 

than work required voltage 

of electromagnetic valve 

1.  ignition switch is in the opening 
position 

2.    Voltage of transmission control 
unit power supply >17 V for 60s 

 

3. Circuit 

sketch 

T

C

U

电磁阀

换挡器

档位开关

LEVER

REVERSE

START

VBS5

VBS6

VBS7

VBS8

VBS

9

VBS1

0

O

n

O

ff

1

O

n

O

ff2

O

n

O

ff3

O

n

O

ff

4

EMM

INPU

T

SHAFT

SPEED

SE

NSOR

OUTPU

T

SHAFT

t

SPEED

SENSOR

25

26

10

11

9

8

13

12

24

23

22

21

20

7

6

5

4

3

2

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

J-4

1

18

8

1

3

2

12

14

4

11

12

9

10

15

2

1

4

3

6

5

7

7

J-5

5

16

17

J-5

4

J-5

1

J-5

6

J-5

2

J-5

3

4

11

10

10

15

3

CAN H

启动继电器

倒车信号

输出

主继电器

JF-1

IG2

JB-2

CAN L

10

20

J-3

J-1

J-3

J-2

J-2

J-3

J-3

J-3

J-1

8

J-3

J-3

J-3

J-3

J-3

J-3

J-3

J-3

J-1

J-1

J-1

J-1

J-1

J-1

J-1

J-1

J-1

J-1

J-1

J-1

IF36

NL03-2005c

 

4. Diagnostic 

procedures: 

Note: Before carrying out this diagnosis step, observe the data list on fault diagnosis tester and analyze the 
accuracy of the data, as these will help with quick diagnosis. 

1 

Read the fault code again after clearing away the fault code to check if fault codes, except DTC 
P0603, P0604, P1604, P1701, and P1703 exist in the control system. 

A.    Connect fault diagnosis tester to the datalink connector. 

B.  Rotated ignition switch to ON position 

C.    Switch on fault diagnostic device power supply 

D.  Clear DTC code. 

E.    Reset reading fault code, and check if DTCs meet setting condition of fault code in current 

Gears switch 

Main relay 

JF-1 

 

Reverse output 

signal 

 

Start relay JB-2 

Shifter 

Electromagnetic 

valve 

1284

 
 

DTC codes shown 

To step 

DTC P0603, P0604, P1604, P1701, P1703 

Yes 

DTC except for DTC P0603, P0604, P1604, P1701, P1703 

No 

 

 

 

2 

Check power supply and charging system 

A.  Check negative and positive connection of battery is loosed 

B.  Check engine harness connector was damaged or loosed 

 

 

 

 

3 

Check TCUpower supply circuit 

 

A.  Rotated ignition switch to OFF position. 

B.    Disconnect TCU harness connector J-1 

C.  Rotated ignition switches to ON position. 

D. 

 

Measure resistance value of automatic 
transmission harness connector J-1No.16 
terminal and reliable grounding 

E.    Measure voltage value of automatic transmission 

harness connector J-1No.16 terminal and reliable 
grounding 

自动变速器控制模块线束连接器

J-1

1

9

2

10

3

11

4

12

5

13

6

14

7

15

8

16

SL03-0034c

Results 

Test items 

Standard value 

J-1(16)-Reliable grounding resistance value 

10 kΩ or higher 

J-1(16)-Reliable grounding voltage value 

11 - 14 V 

Does it conform to the standard value? 

No

Yes

Refer to3.4.7.6 fault diagnosis code (DTC) 
chapter index 

Yes

No 

Connect to harness connector or replace harness 

Auto-transmissioncontrol module harness connectorJ-1

1285

 
 

 

 

 

4 

Check TCU grounding circuit 

A.  Rotated ignition switch to OFF position. 

B.    Disconnect TCU harness connector J-1 

C.  Rotated ignition switches to ON position. 

D.  Measure resistance value of automatic transmission harness connector J-1No.8 terminal and reliable 

grounding 

E.    Measure voltage value of automatic transmission harness connector J-1No.8 terminal and reliable grounding 

Results 

Test Items 

Standard value 

J-1(16)-Reliable grounding resistance value 

Less than 3 Ω 

J-1(16)-Reliable grounding voltage value 

0 V 

Does it conform to the standard value? 

 

 

 

5 Replace 

TCU 

Refer to3.5.7.8 replace automatic transmission control module 

 

 

6 

Go to automatic transmission fresh process. 

Refer to 3.5.7.4 replace automatic transmission refresh process 

 

 

7 

Use fault diagnosis tester to confirm if DTC is stored again. 

A.    Connect fault diagnosis tester to the data link connector. 

B.  Rotated ignition switches to ON position. 

C.    Clear DTC code. 

D.    Start and run the engine at idle speed to warm up the engine for at least 5min. 

E    Read control system DTC code again to confirm that the system has no DTC code exported. 

No

Yes 

Circuit fault, repair circuit. 

No

Yes 

Circuit fault, repair circuit. 

Next 

Next 

1286