Wacker Neuson GP 3800A, Repair Manual

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GP Repair Troubleshooting
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6.21 Auto Idle Circuit Troubleshooting—Flowchart 4A
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Examine the mechanical linkage. Be
sure all parts are functioning.
Replace auto
idle switch.
Auto Idle Malfunctioning
Checking voltage to auto idle solenoid
With the engine running, check the DC voltage
between the two white/red (W/R) wires. There
should be 28±2VDC.
Is
correct voltage
measured?
Is
correct voltage
measured?
Is
correct resistance
measured?
No
Yes
Is
correct voltage
measured?
No Yes
Is switch
functioning?
No
Yes
Confirm the solenoid is malfunctioning by
measuring its coil’s resistance and by checking
action of plunger. Replace the idle solenoid.
Check fuse; replace if blown.
Check voltage at fuse.
There should be 20±2VDC.
Checking auto idle circuitry
between fuse and auto idle unit
Check function of auto idle switch.
Replace auto
idle unit.
Repair
wiring between
fuse and auto
idle unit.
Yes
No
Check voltage to auto idle unit by
measuring between red and black
wires. There should be 20±2VDC.
Is rectifier
functioning?
Replace the
rectifier.
Yes
Yes
No
Checking auto idle circuitry
between generator and fuse
Check the rectifier.
Replace the
stator.
Check wiring
between winding
and fuse.
Also check sensing
wires.
Repair wiring as
needed.
No
Check resistance of DC winding.