C.E. Niehoff & Co. N1506-1 Troubleshooting Guides - Manual (Page 5)

Page 5
TG0018A
Yes No
With engine off, is battery voltage present at alternator 14 V B+ terminal?
Chart 2 – No 14 V Alternator Output – Test Circuit
Yes No
Connect DMM red lead to pin E on alternator-to-regulator harness plug. Connect black
lead to pin C on same plug. Does battery voltage exist?
Alternator is defective.
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Repair vehicle wiring as necessary. Continue test.
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Substitute a known good regulator. Run engine. Is system
charge voltage at regulator setpoint?
Yes No
Alternator is
defective. Original regulator
was defective.
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Figure 4 – Alternator-to-Regulator Harness Plug
PIN CONNECTIONS
Pin A F–
Pin B SCR Gate
Pin C B–
Pin D 28 V B+
Pin E 14V B+
A
B
C D
E
Yes No
With engine running, does 28 V system charge properly?
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Go to Chart 1, page 4.
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Section 3: Advanced Troubleshooting
(CONT’D)