Yamaha DT200L 1984-1988 Service Manual page 212

ELEC
YAMAHA POWER VALVE SYSTEM
Troubleshooting
If the Yamaha Power Valve System should
become inoperative, the troubleshooting acids
will be useful.
1. Step A
Check valve operation (When
the main switch is turned on, valve
operates on cycle.)
Poor
operation
Go to step B.
Check valve operation (When the
engine is started, valve is
closed.)
Poor
operation
Check connection between CDI unit
and YPVS control unit (Refer to
"WIRING DIAGRAM" section.)
OK
OK
Poor
connection
Yamaha Power Valve System
circuit is good.
Correct.
Check YPVS control unit condition
(Refer to "YPVS Control Unit Test'
section.)
OK
CDI unit is faulty, replace it.
Poor
condition
Replace YPVS control unit.
2. Step B
Check battery for voltage and
specific gravity (Refer to "Battery
Inspection" section.)
OK
Check entire Yamaha Power Valve
System for connections (Refer
to "WIRING DIAGRAM" section
OK
Check fuse and fuse connections.
OK
Check servomotor unit condition
(Refer to "Servomotor Test" section.)
OK
YPVS control unit is faulty, replace it.
Low voltage
and low
specific
gravity
Poor
connection
Weak connec-
tion or open
circuit
Poor
condition
Recharge battery.
Correct.
Correct connection or
replace fuse.
Replace servomotor unit.
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