C.E. Niehoff & Co. N1313 Troubleshooting Guides User Manual
Page 7
Page 7
TG16F
Section C: Advanced Troubleshooting
(CONT’D)
Yes
No
Alternator is defective.
Unplug alternator-to-regulator 5-pin harness from regulator. Connect red lead from DMM to pin A in plug. Connect
black lead to pin D in plug. Does resistance read 1.0 ± 0.2 ohms?
Chart 3b
– No 28 V Alternator Output – Test OVCO Circuit (28 V LED on N3222 steady RED)
Yes
No
Replace existing regulator with known good regulator.
Run engine. Does OVCO trip?
Alternator is defective.
Original regulator is
defective.
Yes
No
Original regulator
is defective.
Replace regulator with known good regulator. Run
engine. Does OVCO trip?
Chart 3a
– No 14 V Alternator Output – Test OVCO Circuit (14 V LED on N3222 steady RED)
Alternator is defective.
Yes
No
Set DMM to
auto-ranging scale. Connect red lead from DMM to pin A in plug. Connect black lead
to B– terminal. Does resistance read OL (out of limits)? Then connect red lead to pin D and black lead
to B– terminal. Does resistance read OL (out of limits)?
Alternator is defective.
Yes
No
Alternator is defective.
Disconnect alternator-to-regulator 3-pin harness from regulator. At receptacle on regulator, connect red lead from
DMM to pin C. Connect black lead to B– terminal. Does resistance read OL (out of limits)?
Figure 5 – Alternator-to-Regulator 3-Pin Harness Receptacle
PIN CONNECTIONS
A 14 V B+
B unused
C 14 V Control
Chart 3
– OVCO Trip N3039 only – Determine 28 V or 14 V (LEDs on N3222 will determine which output)
Yes
No
28 V side tripped OVCO circuit.
Go to Chart 3b.
With meter red lead on 28 V B+ at battery and black lead on chassis ground, start engine.
Watch meter dial: Does meter read battery charge above 29 V?
14 V side tripped OVCO circuit.
Go to Chart 3a.
Figure 6 – Alternator-to-Regulator 5-Pin Harness Plug
PIN CONNECTIONS
A
F–
B
unused
C
B–
D
28 V B+
E
Phase
A
B
C