C.E. Niehoff & Co. C651/C654 Troubleshooting Guides - Manual (Page 6)

Page 6
TG0010C
(CONT’D)
Section 3: Advanced Troubleshooting
Yes No
With engine off, is battery voltage present at alternator 14 V B+ terminal?
Chart 3 – 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.
T T T T T
Repair vehicle wiring as necessary.
Continue test.
T T T T T
T T T T T
Substitute a known good regulator. Run engine. Is regulator
setpoint voltage present?
Yes No
Alternator is
defective. Original regulator
was defective.
T T T T T
T T T T T
T T T T T T T T T T
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+
Pin F F+
Pin G AC Signal
Pin H Not Used