Lexus SC300 / Lexus SC400. Service manual — part 693

7.

INSPECT CHARGING CIRCUIT WITHOUT LOAD
HINT: If a battery/alternator tester is available, connect the
tester to the charging circuit as per manufacturer’s instruc-
tions.
(a) If a tester is not available, connect a voltmeter and

ammeter to the charging circuit as follows:

•

Disconnect the wire from terminal B of the
alternator and connect it to the negative (–) probe
of the ammeter.

•

Connect the positive (+) probe of the ammeter to
terminal B of the alternator.

•

Connect the positive (+) probe of the voltmeter to
terminal B of the alternator.

•

Ground the negative (–) probe of the voltmeter.

(b) Check the charging circuit as follows:
With the engine running from idling to 2,000 rpm, check the
reading on the ammeter and voltmeter.

Standard amperage: 10 A or less

Standard voltage: 13.9–15.1 V at 25

°

C (77

°

F)

13.5–14.3 V at 115

°

C (239

°

F)

If the voltmeter reading is greater than standard voltage, re-
place the IC regulator.

If the voltmeter reading is less than standard voltage, check
the IC regulator and alternator as follows:

•

Remove the engine under cover.

•

With terminal F grounded, start the engine and
check the voltmeter reading of terminal B.

•

If the voltmeter reading is greater than standard
voltage, replace the IC regulator.

•

If the voltmeter reading is less than standard
voltage, check the alternator.

•

Reinstall the engine under cover.

–

CHARGING SYSTEM

On–Vehicle Inspection

CH–7

8.

INSPECT CHARGING CIRCUIT WITH LOAD
(a) With the engine running at 2,000 rpm, turn on the high

beam headlights and place the heater blower switch at
”HI”.

(b) Check the reading on the ammeter.

Standard amperage: 30 A or more

If the ammeter reading is less than standard amperage, re-
pair the alternator. (See page

CH–9

)

HINT: With the battery fully charged, the indication will some-
times be less than standard amperage.

9.

REINSTALL ENGINE UNDER COVER

CH–8

–

CHARGING SYSTEM

On–Vehicle Inspection

ALTERNATOR

COMPONENTS FOR REMOVAL AND
INSTALLATION

REMOVAL OF ALTERNATOR

1.

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ”LOCK” position and the negative (–) termi-
nal cable is disconnected from the battery.

2.

REMOVE ENGINE UNDER COVER

3.

REMOVE DRIVE BELT
Loosen the belt tension by turning the drive belt tensioner
counterclockwise, and remove the drive belt.
HINT: The pulley bolt for the belt tensioner has a left–hand
thread.

–

CHARGING SYSTEM

Alternator

CH–9

4. REMOVE

ALTERNATOR

(a) Disconnect the alternator connector.
(b) Remove the cap and nut, and disconnect the alternator

wire.

(c) Remove the bolt, and disconnect the A/T oil cooler pipe

bracket.

(d) Remove the nut and alternator.

COMPONENTS FOR DISASSEMBLY AND
ASSEMBLY

DISASSEMBLY OF ALTERNATOR

1.

REMOVE REAR END COVER
(a) Remove the nut and terminal insulator.

CH–10

–

CHARGING SYSTEM

Alternator