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Page 5

TG97A

MASTER BATTERY SWITCH OFF, KEY OFF, ENGINE OFF:  

Disconnect alternator-to-regulator harness at regulator and perform ALL tests 

in table below at harness plug. If ANY expected values are not obtained, unit 

indicated in "TESTED CIRCUIT" column is faulty. 

Regulator responded to overvoltage condition. 

See "Check for OVCO Condition" on page 4.

Shut down vehicle, then restart engine. Wait until system voltages stabilizes. Does alternator function normally?

•  TEST MEASUREMENTS ARE TAKEN AT ALTERNATOR HARNESS PLUG. Test measurements from an  

extended harness plug may affect results. 

•  IF AVAILABLE, CONNECT A CEN A10-151 IN-LINE TEST TOOL TO HARNESS PLUG AND CONDUCT 

TESTS FROM A10-151 SOCKETS. Otherwise perform all tests directly from harness plug sockets. 

•  CHECK CONDITION OF FUSES IN REMOTE MOUNTED REGULATOR HARNESS BEFORE TESTING.

•  BEFORE TESTING, VERIFY THE FOLLOWING AND REPAIR/REPLACE IF NOT TO SPECIFCATION: 

—Batteries for state-of-charge (24.5-28.0 V), condition, and secure connections.

—Master battery switch for function.

TEST 

NO. 

METER SYMBOL 

& SCALE

METER (+)

METER (–)

TESTED CIRCUIT

EXPECTED 

VALUE

1

VDC

Socket A

Socket 2

Regulator B+, B–

Battery voltage

2

VDC

Socket D

Socket 2

Regulator B+, B–

Battery voltage

3

VDC

Socket 1

Socket 2

Regulator B+, B–

Battery voltage

4

Ohms 

Socket B

Socket 2

Alt. Field Coil

1 – 1.5 ohms

5

Ohms 

Socket C

Socket 2

Alt. Field Coil

1 – 1.5 ohms

6

Diode 

Socket 3

Socket 2 

Alt. AC

Blocking

7

Diode 

Socket 2

Socket 3

Alt. AC

Flow

8

Diode 

Socket 3

Sockets A, D, 1

Alt. AC

Flow

9

Diode 

Sockets A, D, 1

Socket 3

Alt. AC 

Blocking

10

Ohms 

Socket 4

Socket 2

Harness/temp sensor

60K-130K ohms 

MASTER BATTERY SWITCH ON, KEY ON, ENGINE ON: 

Test for battery voltage at B+ terminal on alternator 

to ground, then at regulator IGN terminal to ground. Does battery voltage exist at both locations?

Yes

No

Repair vehicle wiring as necessary. Run engine and 

re-test charging circuit. Is charging system perform-

ing properly?

Yes

No

System is operational

Chart 1: No Alternator Output – Test Charging Circuit

CAUTION

When performing the following steps, make sure probes do not touch other sockets, as

 this may create an arc and damage plug.

 

Yes

No

NOTICE

DO NOT MODIFY THIS CHART

Section C: Advanced Troubleshooting 

Содержание C850

Страница 1: ...eshooting 4 Section C Advanced Troubleshooting 5 Required Tools and Equipment Digital Multimeter DMM Ammeter digital inductive Jumper wires Testing Guidelines Professional service technicians rely on the following guidelines when testing electrical components Voltage testing Set meter to proper scale and type AC or DC Zero meter scale or identify meter burden by touching meter leads together Meter...

Страница 2: ...nator shaft rotating at a suitable speed After the regulator detects shaft rotation it gradually applies field current preventing an abrupt mechanical load on accessory drive system Soft start may take up to 20 seconds after rotation and energize signals are sensed Refer to Figure 1 for alternator terminal locations Refer to Figure 2 for alternator to regulator harness plug socket outputs Figure 1...

Страница 3: ...t may be used with or with out a J1939 temperature sense harness The A2 387 regulator features include Overvoltage circuit cutoff OVCO that disables regula tor when voltage above 32 volts is detected for more than 3 seconds Temperature voltage compensation that senses ambi ent temperature within the battery box and adjusts out put voltage as necessary to maintain voltage set point when used with t...

Страница 4: ...r regulator Digital Multimeter DMM Ammeter digital inductive Jumper wires 4 Connect meters to alternator Connect DMM red lead to alternator B terminal Connect DMM black lead to alternator B terminal Clamp inductive ammeter onto B cable 5 Operate vehicle and observe charge voltage Charge voltage should increase and charge amps should de crease Battery is considered fully charged when charge voltage...

Страница 5: ...ry switch for function TEST NO METER SYMBOL SCALE METER METER TESTED CIRCUIT EXPECTED VALUE 1 VDC Socket A Socket 2 Regulator B B Battery voltage 2 VDC Socket D Socket 2 Regulator B B Battery voltage 3 VDC Socket 1 Socket 2 Regulator B B Battery voltage 4 Ohms Ω Socket B Socket 2 Alt Field Coil 1 1 5 ohms 5 Ohms Ω Socket C Socket 2 Alt Field Coil 1 1 5 ohms 6 Diode Socket 3 Socket 2 Alt AC Blockin...

Страница 6: ...es resistance read 1 ohm Alternator is faulty Original regulator is faulty Yes No 1 Unplug alternator to regulator harness from regulator 2 Connect DMM red lead to harness plug socket C 3 Connect DMM black lead to harness socket 2 Does resistance read 1 0 1 5 ohms Alternator is faulty If you have questions about your alternator or any of these test procedures or if you need to locate a Factory Aut...

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