C.E. Niehoff & Co. N1233 Troubleshooting Guides - Manual (Page 4)

Page 4
TG0021A
Section 3: Advanced Troubleshooting
Self-energized alternator may have lost magnetism. Touch steel tool to shaft to detect
any magnetism. Is shaft magnetized?
Install a jumper from B+ terminal on alternator to
E terminal on regulator. Momentarily (1 sec.) jumper
E terminal on regulator to D+ terminal on regulator.
Touch shaft with steel tool to detect significant mag-
netism. Is shaft magnetized?
Yes No
Yes No
Retest alternator.
Unplug alternator-to-regulator harness. Connect
DMM across pin D and pin C in harness plug.
Does battery voltage exist?
Yes No
Alternator is defective.
Figure 3 – Alternator-to-Regulator Harness Plug
Chart 1 – No Output
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PIN CONNECTIONS
Pin A F–
Pin B Phase
Pin C B–
Pin D B+
Pin E D+
Pin F F+
Install a jumper from pin F in harness plug to B+
terminal on alternator. Momentarily (1 sec.) jumper
pin A in harness plug to alternator B– terminal.
Touch shaft with steel tool to detect significant
magnetism. Is shaft magnetized?
Yes No
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Unplug alternator-to-regulator harness. Connect
DMM across pin D and pin C in harness plug.
Does battery voltage exist?
Yes No
Alternator is defective.
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Install a jumper from pin F in harness plug to B+
terminal on alternator. Momentarily (1 sec.)
jumper pin A in harness plug to alternator B–
terminal. Touch shaft with steel tool to detect
significant magnetism. Is shaft magnetized?
Yes No
Alternator is defective.
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Install a jumper from B+ terminal on alternator to
E terminal on regulator. Momentarily (1 sec.) jumper
E terminal on regulator to D+ terminal on regulator.
Touch shaft with steel tool to detect significant mag-
netism. Is shaft magnetized?
Yes No
Repair vehicle circuit to E terminal. Vehicle
charging circuit test is complete.
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Unplug alternator-to-regulator harness.
Connect DMM across pin D and pin C in
harness plug. Does battery voltage exist?
Yes No
Alternator is defective.
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Set DMM to diode test. Connect black lead
of DMM to pin E in harness plug. Connect
red lead to B-terminal or alternator. DMM
should read voltage drop. Reverse leads.
DMM should read OL.
Yes No
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Alternator is defective.
Regulator is defective.
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Set DMM to diode test. Connect black lead of DMM
to pin E in harness plug. Connect red lead to B-
terminal or alternator. DMM should read voltage
drop. Reverse leads. DMM should read OL.
Yes No
Alternator is defective.
Alternator is defective.
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Regulator is defective.