John Deere stx38 - Manual (Page 116)

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3/21/97
CIRCUIT OPERATION AND DIAGNOSIS ELECTRICAL
CRANKING CIRCUIT DIAGNOSIS STX38 (SN 210001— ) & STX46
Test Conditions:
• Transaxle/hydro in neutral • Park brake engaged
• PTO switch disengaged • Key switch in run position
• 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 and starter solenoid
terminal—200 red wire
Battery voltage Check battery cable connection,
fusible link (orange wire) and 200
red wires, replace as necessary.
Test Conditions:
• Key switch in start position
Test/Check Point Normal If Not Normal
3. Key switch terminal ST—700
purple wire.
Battery voltage Replace key switch.
4. PTO switch—700 purple wire. Battery voltage Test 700 purple wire.
5. PTO switch—705 purple/
white wire.
Battery voltage Replace PTO switch.
6. Brake interlock switch—705
purple/white wire.
Battery voltage Test purple/white wire.
7. Brake interlock switch—710
purple wire.
Battery voltage Replace brake interlock switch.
8. Starter solenoid terminal. Battery voltage Test 710 purple wire.
9. Starter solenoid ground
terminal.
Greater than 0.0 —less than 0.2
volts Greater than 0.2 volts— check
starter solenoid ground circuit 105
blk wire; 0.0 volts, replace solenoid.
10. Starter solenoid battery
terminal.
Battery voltage Test red battery wire.
11. Starter solenoid starter
terminal.
Battery voltage Replace starter solenoid.
12. Starting motor Battery voltage Check red wire; if OK, test starter.
13. Fuel shut-off solenoid
(optional)—401 yellow wire
Key switch terminal A
—401 yellow wire.
Battery voltage
Battery voltage
Check yellow wire; if OK, test fuel
shut-off solenoid.
Replace key switch.
14. Fuel shut-off solenoid
(optional).
Greater than 0.0—less than 0.2
volts. Greater than 0.2 volts— check
engine ground; if 0.0 volts, replace
fuel shut-off solenoid.