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TG3E

Section A: Wiring Diagram

CEN C701/C701A Alternators 

Description and Operation

C701/C701A

 28 V, 300 A alternators are internally recti-

fied. All windings and current-transmitting components 

are non-moving, so there are no brushes or slip rings to 

wear out. Energize switch activates regulator. Field coil 

is then energized. Regulator maintains alternator output 

voltage at regulated setting as vehicle electrical loads are 

switched on and off. Alternator output current is self-

limiting and will not exceed rated capacity of alternator. 

A2-213

 regulator furnished with most units has D+ 

terminal that can provide signal to vehicle electrical  

system, confirming alternator operation. Regulator also 

has a P terminal that can provide an optional AC voltage 

tap. Regulator also provides overvoltage cutout (OVCO). 

Regulator also has a green lens LED (see page 4).

Figure 2 — C701 and C701A Alternator with Regulator 

B– Terminal

B+ Terminal

D+ Terminal

IGN Terminal

Figure 1 — C701 and C701A

P Terminal

*Thermal switch is not  

factory-installed on all models.

Green lens 

LED 

IGN

P

A2-213

REGULATOR

GREEN LENS LED

D+

R

Section 1: Wiring Diagram

Page 2

TG3F

Summary of Contents for C701

Page 1: ...e sure the meter leads touch source area only Prevent short circuit damage to test leads or source by not allowing meter leads to touch other pins or exposed wires in test area Be sure to use CEN tools designed especially for trou bleshooting CEN alternators when available Resistance ohm testing Set meter to proper scale Be sure to zero the meter scale or identify the meter burden by touching mete...

Page 2: ... current is self limiting and will not exceed rated capacity of alternator A2 213 regulator furnished with most units has D terminal that can provide signal to vehicle electrical system confirming alternator operation Regulator also has a P terminal that can provide an optional AC voltage tap Regulator also provides overvoltage cutout OVCO Regulator also has a green lens LED see page 4 Figure 2 C7...

Page 3: ... charge voltage is at regulator setpoint and charge amps remain at lowest value for 10 minutes 9 If charging system is not performing properly go to Chart 3 page 7 CAUTION SYMPTOM ACTION TABLE 1 System Conditions Check loose drive belt low battery state of charge Check current load on system is greater than alternator can produce Check defective wiring or poor ground path low regulator setpoint Ch...

Page 4: ...sponse of voltage regulator to high voltage condition Inspect condition of electrical system includ ing loose battery cables both positive and negative If battery disconnects from system it could cause high voltage condition in electrical system causing OVCO circuit to trip If you have reset alternator once and electrical system returns to normal charge voltage condition there may have been a one ...

Page 5: ...in harness plug Does battery voltage exist Yes No Alternator is defective With DMM on resistance scale ensure that the field resistance measured between sockets B and C in harness plug is about 1 2 0 2 ohms Yes No Alternator is defective Install a jumper from socket B in harness plug to B terminal on alternator Momentarily 1 sec jumper socket C in harness plug to alternator B terminal Touch shaft ...

Page 6: ...o Stop engine Unplug alternator to regulator harness Set DMM to Diode Test Connect DMM red lead to socket D on alternator to regulator harness plug Connect black lead to alternator B terminal Does continuity exist Regulator is defective Go to Chart 4 page 8 Yes No With engine running verify operation of charging system Is regulator setpoint voltage present Go to Chart 3 page 7 Figure 4 Alternator ...

Page 7: ...eld Socket C Field Socket D AC Socket E B Repair vehicle wiring as necessary Continue test Connect DMM red lead to socket D in harness plug Connect black lead to alternator B terminal Does continuity exist Yes No Alternator is defective Yes Unplug alternator to regulator harness Plug CEN Regulator Bypass Adapter A10 129 into harness plug Make sure black lead does not touch ground Clip red lead to ...

Page 8: ...rive End Housing USE THIS DIODE Figure 6 Alternator to Regulator Harness Plug SOCKET CONNECTIONS Socket A B Socket B Field Socket C Field Socket D AC Socket E B If you have questions about your alternator or any of these test procedures 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 Can...

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