C.E. Niehoff & Co. C627/C628/C631/C656/C657/C658/C671/C680 Troubleshooting Guides - Manual (Page 5)

Page 5
TG30G
Section C: Comprehensive Troubleshooting
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
regulator to B+ terminal on alternator. Touch
shaft with steel tool to detect significant magne-
tism. Is shaft magnetized?
Yes No
Yes No
Figure 7 – Alternator-to-Regulator Harness Plug
Chart 1 – No Output: A2-149 Only
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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 or alternator. DMM should read voltage
drop. Reverse leads. DMM should read OL.
Alternator is defective.

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Yes No
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Go to Chart 3, page 7.
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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 magne-
tism. Is shaft magnetized?
Yes No

Alternator is defective.

Regulator is defective.
Remove jumper from D+ to B+.
Unplug alternator-to-regulator harness. Connect DMM across pin D and pin C in
harness plug. Does battery voltage exist?
Yes No
When conducting this step, ensure that the probes do not touch
other pins, as an arc may damage the wiring in the harness.
CAUTION
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