C.E. Niehoff & Co. N1313 Troubleshooting Guides - Manual (Page 5)

Page 5
TG16F
Section C: Advanced Troubleshooting
(CONT’D)
Shut off engine. With key on, engine off: Test for battery voltage at alternator 28 V B+
terminal. Does battery voltage exist?
Yes No
Repair vehicle wiring or recharge/replace batteries
as necessary. Continue test.
Chart 1 – No 28V Alternator Output – Test Charging Circuit
Jumper 28 V B+ terminal on alternator to E terminal on regulator. Run engine.
Wait 10 seconds. Does alternator charge?
Yes No
STATIC TEST – KEY ON, ENGINE OFF

 
Yes
Turn off engine, leave key off. Remove alterna-
tor-to-regulator 5-pin harness from regulator.
Momentarily (1 second) connect jumper wire
from pin A in regulator harness plug to B–
terminal on alternator. Spark will occur.
Touch steel tool to shaft to detect significant
magnetism. Is shaft magnetized?
No
Regulator is
defective.

 
Alternator is
defective.

Shut down vehicle and restart engine. Does alternator function normally after restart?
Yes No


Regulator responded to overvoltage condition.
Go to Chart 3 on page 7 to troubleshoot OVCO.
Figure 3 – Alternator-to-Regulator 5-Pin Harness Plug
PIN CONNECTIONS
A F–
B unused
C B–
D 28 V B+
E Phase
No energize signal is present. Repair wiring harness
in vehicle energize circuit. Retest alternator.
When performing the
following test, connect
jumper wire away from
pin A or not at pin A.
Spark may erode pin.
CAUTION