Caution – C.E. Niehoff & Co. C653/C653A/C625 Troubleshooting Guides User Manual
Page 8
Page 8
TG13G
Chart 3 – No Alternator Output – Test Charging Circuit
STATIC TEST – ENGINE OFF, BATTERY SWITCH ON, KEY ON
PIN CONNECTIONS
Pin A
F–
Pin B
Phase
Pin C
B–
Pin D
B+
Pin E
D+
Pin
F
F+
Figure 8 – Alternator-to-Regulator Harness Plug
Test for battery voltage at alternator B+ terminal. Does battery voltage exist?
Yes
No
Repair vehicle wiring as necessary.
Continue test.
With engine running: Test for battery voltage at
regulator IGN terminal. Does battery voltage exist?
Yes
No
Repair vehicle wiring as necessary.
Re-test.
With engine off: 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.
Install a jumper from pin F in harness plug to B+ terminal on
alternator. Momentarily (1 sec.) jumper pin A in harness plug to
alternator B– terminal. Touch shaft with steel tool to detect
significant magnetism. Is shaft magnetized?
Yes
No
Alternator is defective.
Turn off battery switch. Disconnect B+ battery cable from alternator. Connect black lead of DMM to pin E in har-
ness plug. Connect red lead to B+ terminal on alternator. DMM should read OL. Reverse leads. DMM should also
read OL.
Yes
No
Alternator is defective.
Reconnect B+ battery cable to alternator. Turn on battery switch. Set DMM to Diode Test. Connect red
lead to pin B in harness plug. Connect black lead to B+ terminal on alternator. Does continuity exist?
Yes
No
Regulator is defective.
With DMM on resistance scale, ensure that the field resistance measured between pins F and A in
harness plug is about 1.2 (±0.2) ohms.
Yes
No
Alternator is defective.
When conducting this step, ensure that the probes do not touch other pins, as an arc may damage the
wiring in the harness.
CAUTION
C625 Alternator: Alternator is defective.
C653 Alternator: Proceed to Chart 4, page 9.
Section D: A2-214 Advanced Troubleshooting
(CONT’D)