John Deere stx38 - Manual (Page 122)

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3/21/97
CIRCUIT OPERATION AND DIAGNOSIS ELECTRICAL
IGNITION CIRCUIT DIAGNOSIS STX30 & STX38 (SN —210000)
Test Conditions:
• Park brake engaged • Seat switch depressed
• Transaxle in neutral • Meter negative (-) lead on engine ground
• PTO switch disengaged • Meter positive (+) lead on numbered test point
• Key switch in run position
Test/Check Point Normal If Not Normal
13. Seat switch—yellow wire. Battery voltage Test 500 yel wire.
14. Seat switch—pink wire. Battery voltage Replace seat switch.
15. Start relay terminal 85—
Remove F2 fuse , check
voltage, then install fuse.
Battery voltage Test pink wire.
Test Conditions:
• Key switch in off position • Key switch connector disconnected
Test/Check Point Normal If Not Normal
16. Start relay terminal 30. Maximum 0.1 ohms Check battery negative cable, frame
ground connection, and 105 blk
wire.
17. Start relay terminal 86. Maximum 0.1 ohms Check 110 blk wire.
18. Start relay terminal 87A. Maximum 0.1 ohms Replace start relay.
19. Key switch connector—wht
wire.
Maximum 0.1 ohms Check 941 wht wire.
20. Engine connector—wht wire. Maximum 0.1 ohms Check 940 wht wire.
21. Key switch connector—blk
wire.
Maximum 0.1 ohms Check 100 blk wire.
22. Key switch terminals G and
M.
Continuity Replace key switch.
Test Conditions:
• Key switch connector connected • Key switch in on position
Test/Check Point Normal If Not Normal
23. Start relay terminal 87A. No continuity to ground. Replace start relay.