C.E. Niehoff & Co. N1246-1 Troubleshooting Guides - Manual (Page 5)

Page 5
TG0049A
Section 3: Advanced Troubleshooting
(CONT’D)
Chart 2 – No 14 V Alternator Output – Test Circuit
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.
T
T
Yes
Set DMM to diode tester. Connect red lead of DMM
to socket G of regulator harness plug and black
lead to each phase pin (B, F, and I) in same plug.
Meter should show voltage drop value.
Then reverse meter lead connections. Meter should
show OL (blocking).
No
T
Alternator is defective.
T
Regulator is defective.
Figure 4 – Alternator-to-Regulator Harness Plug
SOCKET CONNECTIONS
A ° F–
B ° AC1
C ° Not used
D ° B+
E ° P
F ° AC2
G ° B–
H ° B–
I ° AC3