C.E. Niehoff & Co. C505 Troubleshooting Guides - Manual (Page 8)

Page 8 TG70C
Section C: On-Vehicle Troubleshooting
(CONT’D)
No Alternator Output – Test Charging Circuit
• TEST MEASUREMENTS ARE TAKEN ON HARNESS PLUG AT ALTERNATOR. TEST MEASUREMENT AT AN
EXTENDED HARNESS PLUG MAY AFFECT RESULTS.
• REMOTE-MOUNTED REGULATORS: CHECK CONDITION OF FUSES IN WIRING HARNESS BEFORE TROUBLE-
SHOOTING.
• BEFORE STARTING DIAGNOSTIC SEQUENCE, VERIFY THE FOLLOWING AND REPAIR/REPLACE IF NOT
TO SPEC:
—BATTERIES FOR STATE-OF-CHARGE (12.3-12.6 V), CONDITION, AND SECURE CONNECTIONS
—MASTER BATTERY SWITCH FOR FUNCTION
MASTER BATTERY SWITCH ON, KEY ON, ENGINE ON: Test for battery voltage at B+ terminal on alternator
to ground, then at IGN terminal on regulator to ground (See page 2 for more information).
Does battery voltage exist at both locations?
Yes No
Figure 12 – CEN 5-pin A10-140 Inline Harness Tool
Socket Connections
SOCKET CONNECTIONS
Socket A F –
Socket B Phase
Socket C B –
Socket D B+
Socket E Temp sense
MASTER BATTERY SWITCH ON, KEY OFF, ENGINE OFF: Readings of all five tests must pass.
1. Battery voltage test: Connect DMM red lead to socket D in test tool. Connect DMM black lead to socket C in test
tool. Battery voltage should exist.
2. Field coil resistance test: Set DMM to ohms test. Field resistance between socket A in test tool and B+ terminal
on alternator should measure nominal 1.0-1.5 ± 0.2 ohms. Field coil is defective if reading is less than 0.5 ohms or
greater than 3 ohms.
3. Significant magnetism test:
a. Insert one end of jumper wire in socket A in test tool. Momentarily (1 sec.) touch other end of jumper wire
to alternator B– terminal. Spark will occur at B– terminal. Touch steel tool to shaft to detect significant
magnetism.
b. Remove jumper wire.
4. Phase supply test: Set DMM to diode test. Connect DMM black lead to socket B in test tool. Connect red lead to
alternator B+ terminal. DMM should read blocking in this direction. Then reverse leads. DMM should read flow
in this direction. Repeat for socket B and B– terminal. Tests should read flow in one direction and blocking in
the other direction.
5. Alternator temperature sensor circuit test: Set DMM to ohms test. Sensor resistance between socket E in test tool
and B– terminal on alternator should measure 80-130K ohms at 70ºF (20ºC). Note: If ambient temperature is
higher, resistance will measure less than listed and vice versa.
Yes No
Alternator is defective.
ENGINE OFF: Disconnect 5-pin alternator-to-
regulator harness plug at regulator and connect
CEN A10-140 inline test tool to harness plug end
only. Make sure connections are secure.
Regulator is defective.
Repair vehicle wiring as necessary. Run engine
and re-test charging circuit. Is charging system
performing properly?
System is operative.
No Yes
A B C D E
If you have questions about your alternator or any of these instructions, or if you need to locate a Factory Authorized Service Dealer, please contact us at:
C. E. Niehoff & Co.• 2021 Lee Street • Evanston, IL 60202 USA
TEL: 800.643.4633 USA and Canada • TEL: 847.866.6030 outside USA and Canada • FAX: 847.492.1242
E-mail us at [email protected]