John Deere stx38 - Manual (Page 144)

ELECTRICAL CIRCUIT OPERATION AND DIAGNOSIS
4 - 60
3/21/97
HEADLIGHTS CIRCUIT DIAGNOSIS STX38 (SN 210001— ) & STX46
NOTE: Fusible link (F1) 201 orange wire is designed to melt internally. You cannot see that the fusible link is bad
by looking at it, test for battery voltage at 200 red wire at key switch terminal B to verify fusible link is good.
Test Conditions:
• Key switch in RUN position • Headlights switch ON (engaged)
• Meter negative (-) lead on battery negative (-)
terminal
• Meter positive (+) lead on numbered test point
Test/Check Point Normal If Not Normal
1. Battery positive terminal 11.8—13.2 volts Test battery
2. Key switch terminal B (200 red
wire).
Battery voltage Check battery cable connection,
fusible link 201 orange and 200 red
wire.
3. Key switch terminal A (400
yellow wire).
Battery voltage Replace key switch.
4. PTO switch 400 yellow wire. Battery voltage Test 400 yellow wire.
5. Headlights switch 450 yellow/
white wire.
Battery voltage Replace 450 yellow/white wire.
6. Headlights switch 451 yellow/
white wire.
Battery voltage Replace headlights switch.
7. Headlights kit harness yellow
wire.
Battery voltage Replace 451 yellow/white wire.
8. Headlights kit light sockets red
wires.
Battery voltage Replace headlights kit light sockets
and harness.
9. Headlights kit harness black
wires and tractor harness 120
black wire at W2 engine
ground.
Battery voltage If ground circuit is good, replace
bulbs.