301 

No. 216 Incorrect indication of speedometer   

Malfunction Cause 

Solution 

Speed sensor fails or damaged 

1) Lift the vehicle with double props lifter, and shift the gear to 
accelerate; view the waveform of the pulse signal from sensor 
by oscilloscope; if the pulse signal is disconnected, then the 
speed sensor should be replaced; 
2) While measuring the voltage between terminals of speed 
sensor, place igniting switch to ON and turn the wheel slowly; 
the voltage between #1 and #3 terminal of speed sensor 
should be varied from 0.5 to 9 V and voltage between #2 and 
#3 should be about 8 V; #2 terminal is earthing wire; the 
resistance between #2 terminal and body (earth) measured by 
Ohm grade of multi-meter is zero, which is in conducting state; 
if all the measured values are in normal range, speedometer 
sensor should be replaced. 

Drive or driven gear of speedometer is 
worn out 

3) Lift the vehicle with double props lifter, and shift the gear to 
accelerate; view the waveform of the pulse signal from sensor 
by oscilloscope; if the pulse signal is disconnected or broken 
down, then the speedometer should be checked first for 
broken sensor; the final driven gear in speed sensor and drive 
gear of transmission output shaft should be dismantled and 
checked if there is broken tooth; if yes, the gear should be 
replaced. 

Conducting state or poor contact between 
speed sensor connection and instrument 
loop 

4) Check the cable of speed sensor connection and instrument 
loop if there is broken sleeve resulting in short-circuit; if yes, 
harness should be repaired or replaced; 
5) Remove plugs of speed sensor instrument PCB and 
measure their resistance separately with multi-meter; the 
resistance between #2 terminal of speed sensor and A9 
terminals of instrument plug should be zero as conducting 
state; so as the resistance between #3 terminal of speed 
sensor and A10 of instrument plug, and between #1 terminal 
of speed sensor and A11 of instrument plug; 

Fluctuation of power supply for instrument 
loop 

6) Check the rear connections of instrument panel, please 
re-connect or replace if there is loose or poor contact; 
Measure voltage of terminal B4 for normal 12V; instrument 
connectors B7 and B8 are bond straps; place igniting switch to 
ON position, measure the voltage between A10t A9, which 
should be about 8V; connector A9 is bond strap and A11 is 
signal cable for speedometer. 

Malfunction of internal electronic circuit for 
speedometer or stuck actuating 
mechanism 

7) Check PCB of speedometer for signs of sealing-off or 
burning. Because the electronic circuit of speedometer 
converts the frequency signal from wheel speed sensor to 
useful voltage signal to control circuit of speedometer and 
drive the motor of odometer, if there is sealing-off or poor 
contact, the discontinuous power supply for electronic circuit 
will result in unstable speedometer due to irregular swing of 
speedometer pointer. Test the combined instrument with 
testing bench; 
8) Check the internal actuating mechanism of speedometer for 
dropping off or check the drive motor and pointer for blocking 
by dirt, which may result in blocked or damaged speedometer; 
if yes, clean or replace instrument assembly. 

Incorrect indication 
of speedometer 

The types of tyres for front wheels are 
different. 

Replaced with tyres of same specification as original 

 

 
 

 

 

302 

 

Lift the vehicle with lifter, and shift the gear to 
accelerate the engine; connect oscilloscope to #1 
pin of speed sensor to view the waveform of the 
pulse signal 

Incorrect indication of 
speedometer 

Measure the voltage between terminals of speed sensor, place 
igniting switch to ON and turn the wheel slowly; the voltage 
between #1 and #3 terminal of speed sensor should be varied 
from 0.5 to 9 V 

Check the rear connections of 
instrument panel and power supply 
of instrument 

Check, adjust and 
repair 

Check if there is conducting state or break 
between speed sensor connection and 
instrument loop 

Repair connection or 
replace harness 

Check malfunction of internal 
electronic circuit for speedometer or 
stuck actuating mechanism 

Replace instrument 
assembly 

Check if 
speedometer is 
damaged 

Replace speed 
sensor 

Replace drive or 
driven gear of 
speedometer 

Check drive or driven 
gear of speedometer 

Abnormal

Normal

No 

Yes

Normal

Abnormal

 
 

 

 

303 

 
No. 217 Kilometrage on LCD of odometer will accumulate automatically after the engine starts   

Malfunction Cause 

Solution 

Short-circuit of instrument PCB 

1) Check PCB of speedometer whether it is burnt or of 
short-circuit; because the electronic circuit of 
speedometer converts the frequency signal from wheel 
speed sensor to useful voltage signal to control circuit of 
speedometer and drive the motor of odometer; if the 
PCB is short-circuit, will result in discontinuous power 
supply for electronic circuit and then affect to 
speedometer; 
2) Check PCB of instrument for short-circuit due to 
soldering sealing-off of dropping-off; if yes, check and 
repair or replace instrument assembly; 

Short-circuit of odometer drive motor circuit 

3) Place igniting switch to ON position, measure with 
voltage grade of multi-meter if voltage of odometer drive 
motor is in normal range; measure if resistance of drive 
motor is in normal range; check if short-circuit of drive 
circuit results in abnormal working of odometer motor 
and moving of odometer kilometrage; repair drive circuit 
or replace drive motor; 

Short-circuit of centralized controller 

4) Check centralized controller for “always-ON" of A3 
speed signal to instrument due to internal short-circuit or 
burn-out, which will result in automatic moving of 
odometer kilometrage; 
5) 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, check and repair 
centralized controller or replace centralized controller; 

Internal short-circuit or damage of ECU for EPS 
(Electrical Power-assisted Steering) 

6) Besides odometer, the pulse signal from speed sensor 
is also provided for centralized controller and EPS, so 
the normal working of speedometer will be affected by 
damage or short-circuit of any module of them; 
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 works 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. 

Wrong connection of harness 

Connect the harness again; 

Kilometrage on 
LCD of odometer 
will move 
automatically after 
start-up of engine 

Malfunction of speed sensor 

Replace speed sensor 

 

 
 

 

 

304 

 

Replace 
centralized 
control module 

Kilometrage on LCD of odometer will 
accumulate automatically after 
start-up of engine 

Lift the vehicle with lifter, remove speed 
sensor and start up engine; connect 
oscilloscope on signal wire (#1 terminal) of 
speed sensor and view the signal from 
sensor 

Check centralized controller; remove plugs of 
speed sensor and EPS; 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; measure if there is pulse signal 

Check PCB of instrument and 
odometer drive motor circuit 
for short-circuit due to 
soldering sealing-off of 
dropping-off 

Replace instrument 
assembly 

Check EPS ECU internal circuit for 
short-circuit or break 

Replace EPS ECU 

Wrong connection of 
harness 

Malfunction of speed 
sensor 

Connect the 
harness again 

Replace speed 
sensor

Without signal

Without signal

With signal 

With signal