C.E. Niehoff & Co. C702D Troubleshooting Guides - Manual (Page 5)

Page 5 TG65A
Section C: Advanced Troubleshooting
(CONT’D)
Figure 3 – Alternator-to-Regulator Harness Plug
Chart 1 – No Alternator Output
With engine running, does battery voltage exist at alternator B+ terminal and regulator IGN terminal?
Yes No
Repair vehicle harness circuit to IGN terminal on regulator
or B+ terminal on alternator.


With key off, engine off: Unplug alternator-to-regulator harness. Connect DMM on DC volt
scale across pins C and D in harness plug. Does battery voltage exist?
Yes No

Alternator is defective.
With DMM on resistance scale, ensure that the field resistance measured between pins F and C in
harness plug is about 1.3 (±0.2) ohms.
Yes No
Alternator is defective.



Install a jumper from pin F in harness plug to B+ terminal on alternator. Touch shaft with steel tool to
detect significant magnetism. Is shaft magnetized?
Yes No


Alternator is defective.
CONNECTIONS
A B+ Sense
B AC IN 2
C B–
D B+
E AC IN 1
F F+






When conducting this step, ensure that the probes do not touch other pins, as an
arc may damage the wiring in the harness.
CAUTION
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]
Yes No
Alternator is
defective.
 
Thermal switch
in control unit
is defective.
Set DMM to diode test. Connect black lead of DMM to B+ terminal on alternator. Connect
red lead to pin B on harness plug. DMM should read voltage drop. Reverse leads. DMM
should read OL.