C.E. Niehoff & Co. N1506-1 Troubleshooting Guides - Manual (Page 4)

Page 4
TG0018A
Section 3: Advanced Troubleshooting
With engine off and key on, is battery voltage present at BOTH alternator 28 V and 14 V B+ terminals?
Yes No
Repair vehicle wiring as necessary. Continue test.
Run engine and re-test charging circuit for operation.
Chart 1 – No 28V Alternator Output – Test Charging Circuit
Jumper 28 V B+ terminal on alternator to ENG terminal on regulator. Run engine. Does alternator charge?
Yes No
Remove jumper wire. Go to ENG terminal on regulator.
With engine running, test for battery voltage going into
ENG terminal from battery. Does battery voltage exist?
Yes No
Repair vehicle circuit to ENG terminal.
Vehicle charging circuit test is complete.
! ! ! ! !
! ! ! ! !
! ! ! ! !
! ! ! ! ! ! ! ! ! !
! ! ! ! !
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
magnetism. Is shaft magnetized?
No
! ! ! ! !
! ! ! ! ! ! ! ! ! !
Alternator is
defective.
! ! ! ! !
Yes No
Connect DMM red lead to pin D on alternator-to-regulator harness plug. Connect black
lead to pin C on same plug. Does battery voltage exist?
Alternator is defective.
! ! ! ! !
Figure 3 – Alternator-to-Regulator Harness Plug
PIN CONNECTIONS
Pin A F–
Pin B SCR Gate
Pin C B–
Pin D 28 V B+
Pin E 14V B+
A
B
C D
E
Regulator is defective.
! ! ! ! !