C.E. Niehoff & Co. N1388-1 Troubleshooting Guides - Manual (Page 4)

Page 4
TG0047A
Section C: Advanced Troubleshooting
Chart 1 – No Output
If you have questions about your alternator or any of these test procedures, or if you need to locate a Factory Authorized Service Dealer, please contact us at:
C. E. Niehoff & Co.• 2021 Lee Street • Evanston, IL 60202 USA
TEL: 800.643.4633 USA and Canada • TEL: 847.866.6030 outside USA and Canada • FAX: 847.492.1242
E-mail us at [email protected]
Energize switch on, engine off: Disconnect harness from energize receptacle. Check for battery voltage
between B– terminal on alternator and socket B on energize harness plug end.
Ignition switch off: Reconnect energize harness. Disconnect regulator-
to-alternator harness. Momentarily (1 sec.) jumper socket A in regula-
tor receptacle to B– terminal on alternator. Touch shaft with steel tool
to detect any magnetism. Is shaft magnetized?
Yes No
Yes No
Repair vehicle wiring to
energize receptacle.
T
T T
T
Check energize switch
and vehicle wiring. With regulator-to-alternator harness and energize harness disconnected,
perform series of tests with DMM:
1) With meter set on ohms, connect red lead to pin B of energize recep-
tacle and black lead to socket B of regulator receptacle. Meter should
read 40-55 ohms.
2) With meter set on ohms, check field coil resistance across socket A of
regulator receptacle and B+ terminal on alternator. Resistance should
measure less than 3 ohms.
3) With meter set on ohms, check for continuity between socket C of
regulator receptacle and B– terminal on alternator.
Did all three tests provide correct readings?
Yes No
T T
Regulator is defective. Alternator is defective.
T
Regulator
receptacle
T
Energize
receptacle
Figure 4 — N1388-1 Control Assembly
REGULATOR SOCKET CONNECTIONS
Socket A F –
Socket B Energize
Socket C Ground
Socket D B+
Socket E Not used
ENERGIZE PIN CONNECTIONS
Pin A Not used
Pin B Energize
Pin C Not used
ENERGIZE HARNESS
PLUG END
When performing the following test, be sure to connect
jumper on the ground side and not at socket A in
regulator receptacle. Connecting at ground side will pre-
vent a spark from damaging the socket in the receptacle.
CAUTION