Alternator & Regulator Lexus LS I

DESCRIPTION

Nippondenso 3-phase alternators use 3 positive and 3 negative diodes to rectify current. Charging system voltage is controlled by an internal Integrated Circuit (IC) voltage regulator.

Scheme 1

Scheme 2

ES250

Use Burroughs Tension Gauge (BT-33-73F ) across longest belt run to adjust belt tension. See BELT ADJUSTMENT table.

LS400

Adjust belt tension with 22 lbs. (10 kg) applied on second longest belt run. Belt tensioner should move downward and pointer on belt tensioner should fall within area "A". (Scheme 3)

BELT ADJUSTMENT (1)

Scheme 3

ALTERNATOR OUTPUT

1. Connect charging system test equipment as described in manufacturer's instructions. Check charging system output voltage at 2000 RPM. If output voltage is correct, go to step 3). See «ALTERNATOR OUTPUT SPECIFICATIONS @ 2000 RPM»(/lexus/ls/i-1989-1994/remont/charging-system/#alternator-regulator) table.
2. If output voltage is incorrect, bypass regulator (full field alternator) by grounding terminal "F" at back of alternator. (Scheme 4) Check charging system output voltage once more. If voltage now exceeds output voltage specified in «ALTERNATOR OUTPUT SPECIFICATIONS @ 2000 RPM»(/lexus/ls/i-1989-1994/remont/charging-system/#alternator-regulator) table, replace regulator and recheck. If output voltage is still incorrect, repair or replace alternator.
3. With engine at 2000 RPM, place the heater blower switch on highest setting and turn on headlights (high beam). Ammeter reading should be 30 amps or more. If amperage output is incorrect, repair or replace alternator.

ALTERNATOR OUTPUT SPECIFICATIONS @ 2000 RPM (1)

Scheme 4

ENGINE MAIN RELAY (ES250)

1. Locate main engine relay in underhood fuse/relay panel. Ensure continuity exists between terminals No. 1 and 3, and between terminals No. 2 and 4. (Scheme 1) Continuity should NOT exist between terminals No. 4 and 5. If continuity is not as specified, replace relay.
2. Apply battery voltage across terminals No. 1 and 3. Ensure continuity exists between terminals No. 4 and 5. Ensure continuity DOES NOT exist between terminals No. 4 and 2. If continuity is not as specified, replace relay.

BRUSHES

Check brushes for cracks and a minimum exposed length of .059" (1.5 mm). Replace brushes if damaged or worn. Brushes should slide freely in holders. Install new springs when replacing brushes. Solder brush wire into place.

ROTOR

1. Check rotor for open field windings by measuring resistance across slip rings. Rotor resistance should be 2.8-3.0 ohms. Check rotor for short circuit to ground by connecting ohmmeter between one slip ring and rotor shaft. Continuity should NOT exist.
2. Check slip rings for wear or damage. Turn rotor/slip rings on lathe if necessary. Ensure minimum slip ring diameter is NOT less than .504" (12.8 mm). Check bearing and replace if necessary.

STATOR

Connect ohmmeter between stator leads. Continuity should exist between all stator leads. Connect ohmmeter between one stator lead and metal core. Continuity should NOT exist.

DIODE ASSEMBLY

1. With diode (rectifier) assembly on bench, connect ohmmeter positive lead to each rectifier terminal and negative lead to positive (+) terminal. (Scheme 5) Continuity should NOT exist. Reverse ohmmeter leads and ensure continuity exists.
2. Connect ohmmeter positive lead to each rectifier terminal and negative lead to each negative (-) terminal. Continuity should exist. Reverse ohmmeter leads and ensure continuity DOES NOT exist. If continuity is not as specified, replace diode assembly.

Scheme 5

OVERHAUL

Note. Overhaul procedures are not available from manufacturer. (Scheme 6)and (Scheme 7) for exploded views of alternator.

Scheme 6

Scheme 7

See also:
• BELT ADJUSTMENT