Quick diagnostic – C.E. Niehoff & Co. N1335 Troubleshooting Guides User Manual
Page 5
Page 5
TG0052A
Section 4: Advanced Troubleshooting
Figure 4 – Alternator-to-Regulator Harness Plug
PIN CONNECTIONS
Pin A
F–
Pin B
Phase 1
Pin C
GND/B–
Pin D
B+
Pin E
Kelvin +
Pin
F
F+
Pin G
Kelvin –
Pin H
Phase 2
Chart 1 –
No Alternator Output –
Quick Diagnostic
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.
T
T
Plug in alternator-to-regulator harness at regulator connector. Connect DMM on DC volt scale across pins C and D
at alternator connector. Does battery voltage exist?
Yes
No
With DMM on resistance scale, does field resistance between pins F and A in harness plug measure ~1.4 (±0.2)Ω?
Yes
No
Alternator is defective.
T
T
Alternator is defective.
T
T
With key off, engine off: Does battery voltage exist at alternator B+ terminal?
Yes
No
Repair vehicle harness circuit to B+ terminal on alternator.
T
T
Set DMM to diode test. Check continuity of rear stator diodes: Connect red lead to pin B in harness plug. Connect
black lead to alternator B+ terminal. Meter should read one diode drop (approx. 0.6 to 0.9 V). Disconnect leads.
Connect red lead to alternator B– terminal. Connect black lead to pin B. Meter should read one diode drop (approx.
0.6 to 0.9 V).
Yes
No
Alternator is defective.
T
T
Set DMM to diode test. Check continuity of front stator diodes: Connect red lead to pin H in harness plug. Connect
black lead to alternator B+ terminal. Meter should read one diode drop (approx. 0.6 to 0.9 V).
Disconnect leads. Connect red lead to alternator B– terminal. Connect black lead to pin H. Meter should read one
diode drop (approx. 0.6 to 0.9 V).
Yes
No
Alternator is defective.
T
T
Go to Page 6 to continue.
With key off, engine off: Unplug alternator-to-regulator harness at alternator and regulator connectors. Check for
continuity at both ends of harness. Does continuity exist at each pin-to-pin?
Yes
No
Harness is defective.
T
T