C.E. Niehoff & Co. N1224 Standard Troubleshooting Guides - Manual (Page 6)

Page 6
TG0045A
Section 5: Advanced Troubleshooting
Test for battery voltage at alternator 28 V B+ terminal. Does battery voltage exist?
Yes No
Repair vehicle wiring as necessary. Continue test.
Run engine and re-test charging
circuit for operation.
Chart 1 – 28 V LED Flashing AMBER – No 28V Alternator Output – Test Charging Circuit
Jumper 28 V B+ terminal on alternator to E terminal on regulator. Wait 10 seconds. Run engine. Does
alternator charge and is 28 V LED flashing GREEN?
Yes No
Turn off engine, leave key on. Remove jumper
wire. Go to E terminal on regulator. Test for
battery voltage going into E terminal from bat-
tery. Does battery voltage exist?
Yes No
STATIC TEST – MASTER SWITCH ON, KEY ON, ENGINE OFF
Repair vehicle circuit
to E terminal. Vehicle
charging circuit test is
complete.
T
T
T
T T
T
T T
Figure 4 – Alternator-to-Regulator Harness Plug
PIN CONNECTIONS
Pin A F+
Pin B AC
Pin C B–
Pin D 28 V B+
Pin E 14V B+
Pin F Unused
Pin G +14 V Kelvin
Pin H SCR Gate
T
Yes
Set DMM to diode test. Connect DMM red lead to pin C on harness plug. Connect black lead to alternator B+
terminal. Reverse leads. Meter should read OL in one direction, and voltage drop in the other direction. Do tests
prove out?
No
T T
Yes
Turn off engine, leave key on. Connect jumper wire
from pin A in alternator-to-regulator harness plug
to B+ terminal on alternator. Spark will occur.
Touch steel tool to shaft to detect significant magne-
tism. is shaft magnetized?
No
Alternator is defective.
T
When performing the following
test, connect jumper wire away
from pin A or not at pin A. Spark
may erode pin.
CAUTION
Alternator is defective. Regulator is defective.