C.E. Niehoff & Co. N1128 Troubleshooting Guides User Manual
Page 8
Page 8
TG0027A
Section 4: Advanced Troubleshooting
(CONT’D)
Yes
No
Alternator is defective.
Unplug alternator-to-regulator 4-socket harness from regulator. Connect red lead from DMM to pin A in
plug. Connect black lead to pin D in plug. Does resistance read 2.2 ± 0.2 ohms?
Chart 4
– 28 V LED Flashing AMBER/ 14V LED Off – NO Alternator Output – Test OVCO Circuit
Yes
No
Replace existing regulator with known good regulator.
Run engine. Does OVCO trip?
Alternator is defective.
Original regulator
is defective.
T
T
T
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Chart 3
– 14 V LED Flashing AMBER/ 28V LED Off – No Alternator Output – Test OVCO Circuit
Yes
No
With red lead from DMM connected to pin A in plug, connect black lead to B– terminal. Does
resistance read OL (out of limits)?
Alternator is defective.
T
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Figure 6 – Alternator-to-Regulator 4-Socket Harness Plug
SOCKET
CONNECTIONS
A
F–
B
Phase Signal AC
C
B–
D
28 V B+
Yes
No
Original regulator
is defective.
Replace regulator with known good regulator.
Run engine. Does OVCO trip?
Alternator
is defective.
T
T
T
T
T
T
T
T
T
T
Yes
No
Alternator is defective.
Unplug alternator-to-regulator 4-socket 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)?
T
T
T
T
T
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T
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T
T
If you have questions about your alternator or any of these test procedures, or if you need to locate a Factory Authorized Service Distributor, please contact us at:
C. E. Niehoff & Co.• 2021 Lee Street • Evanston, IL 60202 USA
TEL: 800.643.4633 USA and Canada • TEL: 847.866.6030 outside USA and Canada • FAX: 847.492.1242
E-mail us at [email protected]