C.E. Niehoff & Co. C622 Troubleshooting Guides User Manual
Page 5
Page 5
TG0011A
Section 3: Advanced Troubleshooting
(CONT’D)
Yes
No
Alternator is defective.
Disconnect ground cable from 28 V battery pack. Unplug alternator-to-regulator harness from regulator.
Connect red lead from DMM to socket S in plug. Connect black lead to alternator 28 V B+ terminal. Does
resistance read 2.2 ± 0.2 ohms?
Chart 1
– 28 V RED LED On Steady – No Alternator Output – Test OVCO Circuit
Yes
No
Reconnect cables. Replace existing regulator with known good regula-
tor. Run engine. Does OVCO trip?
Alternator is defective.
Original regulator is defective.
T
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Yes
No
Original regulator is defective.
Replace regulator with known good regulator. Run engine. Does OVCO trip?
Chart 2
– 84 V RED LED On Steady – No Alternator Output – Test OVCO Circuit
Alternator is defective.
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Make sure batteries are properly charged before proceeding.
Make sure batteries are properly charged before proceeding.
Yes
No
Disconnect cable from alternator 28 V B+ terminal. Set DMM to ohms
scale. Connect red lead from DMM to socket S in plug. Connect black lead
to 28 V B– terminal. Does meter read OL (out of limits)?
Alternator is defective.
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HIGH VOLTAGE . Use extreme
caution when working around 84 V
system. Severe personal injury or death will result from contact.
DANGER