C.E. Niehoff & Co. N1601/N1602/N1603/N1604 Troubleshooting Guides - Manual (Page 7)

Page 7 TG29D
Section C: Advanced Troubleshooting
(CONT’D)
Chart 2 – N3118 and N3223 only – No 14 V Alternator Output – Test Charging Circuit
Figure 7 – Phase Connection 3-Pin Harness Plug
PIN CONNECTIONS
A Phase P1
B Phase P2
C Phase P3
Shut off engine. With key off, engine off: Test for battery voltage of 14 V output terminal on regulator.
Does +14 V battery voltage exist?
Yes No
Repair vehicle wiring as necessary.


Yes
Set DMM to diode tester. Connect red lead of DMM to socket C of regula-
tor harness plug and black lead to each phase pin in phase harness plug.
Meter should show voltage drop value.
Then reverse meter lead connections. Meter should show OL (blocking).
No

Alternator is defective.

Regulator is defective.
Figure 6 – Alternator-to-Regulator 4-Socket Harness Plug
SOCKET CONNECTIONS
A F–
B Phase Signal AC
C B–
D 28 V B+