C.E. Niehoff & Co. C653/C653A/C625 Troubleshooting Guides - Manual (Page 5)

Page 5 TG13G
Section C: A2-146/A2-153 Advanced Troubleshooting
A2-146/A2-153 REGULATOR – THIS PAGE ONLY
Self-energized alternator may have lost magnetism. Touch steel tool
to shaft to detect any magnetism. Is shaft magnetized?
Momentarily (1 sec.) jumper D+ terminal on regula-
tor to B+ terminal on alternator. Touch shaft with
steel tool to detect significant magnetism. Is shaft
magnetized?
Yes No
Yes No
Figure 6 – Alternator-to-Regulator Harness Plug
Chart 1 – No Output


Install a jumper from B+ terminal on alternator to
pin F in harness plug. Momentarily (1 sec.) jumper
pin A to B– terminal on alternator. Touch shaft with
steel tool to detect significant magnetism. Is shaft
magnetized?
Yes No
PIN CONNECTIONS
Pin A F–
Pin B Phase
Pin C B–
Pin D B+
Pin E D+
Pin F F+
Set DMM to diode test. Connect black lead of DMM
to pin E in harness plug. Connect red lead to B+
terminal on alternator. DMM should read OL. Reverse
leads. DMM should also read OL.
Unplug alternator-to-regulator harness. Connect
DMM across pin D and pin C in harness plug.
Does battery voltage exist?
Yes No
Alternator is defective.


Yes No

Alternator is defective.




Alternator is defective.

Regulator is defective.
Install a jumper from B+ terminal on alternator to
pin F in harness plug. Momentarily (1 sec.) jumper
pin A to B– terminal on alternator. Touch shaft with
steel tool to detect significant magnetism. Is shaft
magnetized?
Yes No

Alternator is defective.

Regulator is defective.
Remove jumper from D+ to B+.
 
When conducting this step,
ensure that the probes do not
touch other pins, as an arc
may damage the wiring in the
harness.
CAUTION