305 

 
No. 218 Automatic movement of odometer pointer after start-up of engine   

Malfunction Cause 

Solution 

Conducting state or poor contact 
between speed sensor connection and 
instrument loop, poor contact between 
instrument PCB and bond strap 

1) Remove plugs of speed sensor and instrument plug; 
measure wire resistance between terminals by 
multi-meter separately; the resistance between #1 
terminal of speed sensor and A11 terminal of instrument 
plug should be zero as conducting state; the resistance 
measured by the multi-meter should be infinite, 
otherwise, there is short-circuit and should be repaired; 
2) Check connection cable of instrument panel; Measure 
voltage of terminal B4 by multi-meter for normal 12V; 
instrument connectors B7 and B8 are bond straps; check 
fixing screws of B7 and B8 earth wire and body for 
loosing; if yes, tighten it firmly; 

Short-circuit of internal electronic circuit 
of instrument or tachometer circuit 

3) Check PCB of instrument for short-circuit due to 
soldering sealing-off of dropping-off; if yes, check and 
repair or replace instrument assembly; 
4) Check tachometer for normal working; if there is 
internal short-circuit or break for tachometer, the 
connection between tachometer and speedometer on 
PCB should be checked for short circuit or wrong 
transmission signal which results in fault of odometer and 
instrument assembly should be replaced; 

 
ECU of engine 

5) Remove plugs of centralized controller, EPS and 
speedometer sensor, etc , start up engine and connect 
oscilloscope on A11 terminal of instrument plug wire or 
#9 terminal of engine ECU to view waveform; if there is 
still waveform of signal after removing plugs, the engine 
ECU fails internally and should be replaced; 

 
Short-circuit of centralized controller 

6) Switch multi-meter to voltage grade and igniting switch 
to ON; connect red probe to A3 terminal of centralized 
controller and black probe to bond strap of body; the 
voltage measured should be between 0.5 – 9 V; start up 
engine and view pointer of multi-meter; there will be no 
obvious variation; otherwise, should check and repair 
centralized controller loop and instrument connection or 
replace centralized controller; 

 
Internal short-circuit or damage of EPS 
ECU 

7) Firstly, check speedometer under normal working 
condition: Lift the vehicle with double props lifter, and 
shift the gear to accelerate the engine; view the 
waveform of the pulse signal from sensor by 
oscilloscope; if speedometer is working normally, remove 
plugs of speed sensor and centralized controller, start up 
engine and view if there is pulse signal on oscilloscope; if 
yes, the ECU internal circuit for EPS is broken and 
should be replaced. 

Internal short-circuit of speed sensor 

Replace speed sensor assembly 

Automatic moving of 
odometer pointer after 
start-up of engine 

Wrong connection of harness 

Check and sort out the harness connection again. 

 

 
 

 

 

306 

Short-circuit of internal 
electronic circuit of 
instrument or tachometer 
circuit 

Check if there is conducting state or bad 
contact of bond strap between speed sensor 
connection and instrument loop 

Automatic movement of 
odometer pointer after 
start-up of engine 

Remove plug of speed sensor; lift the vehicle with double props lifter, and 
start up the engine; connect oscilloscope on A11 terminal of instrument 
harness to view for signal 

Check engine ECU for internal 
short-circuit or break 

Check, repair and 
replace 

Replace engine 
ECU 

Check centralized controller for internal short-circuit or 
damage 

Replace instrument 
assembly 

Replace centralized 
controller 

Check EPS 

Replace EPS module (ECU) 

Internal short-circuit of 
speed sensor

Replace speed sensor 
assembly

Connect the 
harness 
again 

Wrong 
connection 
of harness 

Yes 

Normal 

Abnormal 

Normal 

Normal 

Abnormal 

Abnormal 

No 

 
 

 

 

307 

 
No. 219 Incorrect indication or no indication of engine tachometer   

Malfunction Cause 

Solution 

 
Malfunction of power supply circuit for 
instrument  

1) Open fuse unit and check if CLUSTER(10A) AM1(30A) 
and MAIN(80A) in fuse unit is broken; replace if necessary; 
2) Place igniting switch to ON and measure voltage of 
instrument connector B4 with voltage grade of multi-meter; 
the voltage should be equal to the voltage of battery 
(standard voltage: 12V); measure resistance  of instrument 
connectors B7 and B8 to bond strap; the resistance should 
be zero because B7 and B8 are bond straps of instrument; if 
power supply voltage for B4 and resistances for B7 and B8 
are different from normal values, circuit should be checked 
and repaired or fuse should be replaced;   

Conducting state or break of tachometer PCB 

3) Check PCB of tachometer for short-circuit due to soldering 
sealing-off of dropping-off; if yes, check and repair or replace 
instrument assembly;   

Short-circuit or poor contact of engine ECU 
connecting harness, power supply and 
tachometer connecting wire   

4) Remove engine ECU connecting harness and instrument 
harness; measure by resistance grade of multi-meter 
between #54 terminal or engine ECU and B11 connector of 
instrument board; the resistance should be zero as 
conducting state; and measure resistance between engine 
#54 or B11 on instrument board and body (bond strap); the 
resistance should be infinite, otherwise there must be 
short-circuit in this loop.   

Blocked mechanical part of tachometer   

5) Check tachometer coil for blow-out or break; check if 
hairspring blocks with panel while rotating and if there is 
break of hairspring of tachometer coil; if yes, tachometer or 
instrument assembly should be replaced;   

Internal malfunction of tachometer   

6) Dismantle combined instrument assembly with connectors 
connected; connect oscilloscope on B11 terminal of 
instrument connector; start up engine and view if the 
displayed waveform of pulse signal is correct; if yes, the 
tachometer should be checked, repaired or replaced;   

Incorrect indication 
or failure of engine 
tachometer  

 
Malfunction of engine control system   

7) Check rotating speed output signal of engine ECU; 
dismantle engine ECU with connectors connected; connect 
oscilloscope on #54 terminal and start up engine to view if 
the displayed waveform of pulse signal is correct; if without 
pulse display, engine control system should be checked and 
repaired or engine ECU should be replaced;   

 

 
 

 

 

308 

 

Replace fuse of 
instrument

Connect oscilloscope on #54 terminal; start up engine 
and view if the displayed waveform of pulse signal is 
normal 

Check tachometer PCB for 
short-circuit or break 

Check connecting harness of 
engine ECU and tachometer 
for short-circuit or break 

Check, repair and 
replace

Connect oscilloscope on B11 terminal of 
instrument connector; start up engine and 
view if the displayed waveform of pulse 
signal is correct 

Check, repair and 
replace

Check power supply loop for 
instrument; measure voltage of B4 
instrument connector for normal 
about 12 V with voltage grade of 
multi-meter; check fuse for burn-out 

Check and repair engine control 
system or replace ECU

Check, repair or replace 
tachometer 

Replace tachometer or instrument 
assembly

Check tachometer coil for blow-out 
or break; check if hairspring blocks 
with panel while rotating and if there 
is break of hairspring of tachometer 
coil 

Start up engine and view if pointer of tachometer 
is swinging

Incorrect indication or no indication of engine 
tachometer 

Without swinging 

swinging 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Normal