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TG115A
Chart 2: Test OVCO Circuit
Alternator is faulty
Alternator is faulty
Yes
No
Replace existing regulator with known good regulator. Run engine. Does OVCO trip?
Original regulator faulty
Alternator is faulty
If you have questions about your alternator or any of these test procedures, or if you need to locate a Factory Authorized Service Distributor, 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]
Yes
No
Stop engine. Disconnect harness from alternator to regulator. If available, plug CEN A10-114
test tool into alternator only. Otherwise carefully test directly through alternator harness
pins. See Figures 6 and 7 below for reference.
1. Set DMM to ohms test.
2. Connect DMM red lead to alternator B+ terminal.
3. Connect DMM black lead to harness pin F. Does resistance read 1.0-1.5 ± 0.2
Ω
?
Section C: Advanced Troubleshooting (cont.)
Yes
No
1. Set DMM to ohms test.
2.
Connect DMM red lead to alternator B‒ terminal.
3. Connect DMM black lead to harness pin F. Does resistance read OL?
Figure 7: A10-114 Inline Harness
Test Tool
A
B C D E
F
Figure 6: Alternator-to-Regulator
Harness Pin Designations
A
B
C
D
E
F
Pin A = Not used
Pin B = Phase
Pin C = B ‒
Pin D = B+
Pin E = Alt temp sensor
Pin F = F ‒
Figure 8: Vehicle 5-Pin Harness
Pin Designations (for reference)
A
B
C
E
D
Pin A = IGN
Pin B = Batt temp sensor
Pin C = Batt temp sensor
Pin D = D+
Pin E = Batt voltage sensor
