Alternator & Regulator Chevrolet Corvette C4

DESCRIPTION

CS series alternators include a stator, rectifier bridge, and rotor with slip rings and brushes. A built-in regulator incorporates fault detection circuitry.

Most CS series alternators operate with 2 wire connections and a ground path through the mounting bracket. The first wire connection is the BAT (output) terminal. This terminal must be connected to the battery during operation. The second wire connection is through the charge indicator light or an external resistor to the terminal "L" of the regulator. This connection provides initial excitation at start-up.

Three other regulator terminals, "P", "I" and "S", are provided for optional use. Terminal "P" is connected to the stator and may be connected to a tachometer. Terminal "I" provides an alternative method for turning on the alternator without going through the indicator light or external resistor. Terminal "S" may be used to sense electrical system voltage at a remote point on the vehicle. If terminal "S" is not used, the regulator senses internal alternator voltage.

Some CS144 models have 3 auxiliary phase terminals which supply current to operate heated windshields on vehicles so equipped.

No periodic maintenance is necessary. CS144 alternators, except for those with 3 auxiliary phase terminals, can be disassembled and repaired. All CS121, CS130 and CS144 alternators with 3 auxiliary phase terminals are serviced by replacement.

ADJUSTMENTS

No adjustment or maintenance is required on alternator assembly. Regulator voltage is preset and no adjustment is possible.

TROUBLE SHOOTING

Note. For trouble shooting, see TROUBLE SHOOTING article in GENERAL INFORMATION.

ALTERNATOR (2.3L)

Note. The CS-130 alternator cannot be disassembled, and must be serviced as a complete unit.

Removal

Note. Extreme care must be taken during removal and installation not to damage the A/C compressor and condenser hose.

Disconnect negative battery cable. Remove electrical center fuse block shield. Remove serpentine belt. Disconnect electrical connector from alternator. Remove nut and disconnect battery positive connector from alternator. Remove bolt from brace to alternator, rear attaching bolt and front attaching bolt. Remove alternator-out between the engine lifting eyelet and the A/C compressor and condenser hose, to the passenger side, then up and out.

Installation

Install alternator, front attaching bolt but do not tighten, rear attaching bolt, bolt to brace to alternator. Tighten the long bolt to 40 ft.lbs.(54 N.m), short bolt 19 ft.lbs. (26 N.m), brace bolt 18 ft.lbs (25 N.m). Connect battery positive connector and install nut to alternator. Connect electrical connector to alternator. Install serpentine belt, electrical center fuse block shield and connect negative battery cable.

Scheme 1

Scheme 2

ALTERNATOR (3.1L)

Note. The CS-130 alternator cannot be disassembled, and must be serviced as a complete unit.

Remove air cleaner assembly. Disconnect negative battery cable. Disconnect electrical connector from alternator. Remove serpentine belt. Remove bolt from alternator, bolt from brace to alternator, nut from alternator battery terminal and alternator.

Note. If alternator brace is removed, studs must be retightened before installation or damage to the brace may result.

Install alternator, alternator battery terminal and alternator retaining nut, and brace bolts to alternator, but do not tighten bolts to alternator. Tighten the long bolt to 35 ft.lbs.(47 N.m), short bolt 18 ft.lbs. (25 N.m), brace bolt 18 ft.lbs (25 N.m).

Note. Make sure that tightening brace bolts does not bind alternator.

Install serpentine belt. Connect electrical connector to alternator, negative battery cable. Install air cleaner assembly.

Alternator Mounting (3.1L). Scheme 3

Alternator Shim (3.4L A/T & M/T). Scheme 4

Alternator Shields (3.4L A/T & M/T). Scheme 5

Alternator Mounting (3.4L A/T & M/T). Scheme 6

Removal (A/T)

Remove air cleaner assembly. Disconnect negative battery cable. Remove coolant recovery reservoir and set aside. Remove serpentine belt. Remove power steering pipe retaining clip nut from upper alternator stud and remove alternator stud. Raise vehicle and suitably support. Remove right front tire and wheel assembly. Separate lower ball joint from lower control arm. Disconnect drive axle from transaxle, right hand engine splash shield, connectors and wires from alternator, pencil brace bolt from alternator and loosen brace at engine block. Remove alternator lower mounting bolt and alternator

Install alternator and loosely install all mounting bolts.

Note. If replacement alternator does not fit, remove adhesive- backed shim from rear alternator bracket.

Tighten alternator lower mounting bolt to 61 ft.lbs (83 N.m). Install connectors and wires to alternator, right hand engine splash shield, drive axle to transaxle, lower ball joint to lower control arm, tire and wheel assembly. Lower vehicle. Install power steering pipe retaining clip nut to upper alternator stud, serpentine belt, coolant recovery reservoir and connect negative battery cable. Install air cleaner assembly.

Removal (M/T)

Remove air cleaner assembly. Disconnect negative battery cable. Remove coolant recovery reservoir and set aside. Remove serpentine belt. Remove power steering pipe retaining clip nut from upper alternator stud and remove alternator stud. Raise vehicle and suitably support. Remove right front tire and wheel assembly, right hand engine splash shield. Remove connectors and wires from alternator, pencil brace bolt from alternator and loosen brace at engine block.

Separate lower ball joint from lower control arm. Disconnect drive axle from transaxle, outboard drive axle splash shield, inboard drive axle splash shield fastener and engine rear support bracket (splash shield will come off with bracket). Remove alternator lower mounting bolt and alternator

Install alternator and loosely install all mounting bolts.

Note. If replacement alternator does not fit, remove adhesive- backed shim from rear alternator bracket.

Install rear support bracket, inboard drive axle splash shield and fastener to engine rear support bracket. Tighten alternator lower mounting bolt to 61 ft.lbs (83 N.m). Install outboard drive axle splash shield, drive axle to transaxle, lower ball joint to lower control arm, connectors and wires to alternator, right hand engine splash shield, tire and wheel assembly. Lower vehicle. Install power steering pipe retaining clip nut to upper alternator stud, serpentine belt, coolant recovery reservoir and connect negative battery cable. Install air cleaner assembly.

Disconnect negative battery cable. Raise vehicle and suitably support, electrical connection from motor. Remove air duct from blower motor and mounting screws and motor assembly.

Install motor assembly and mounting screws, air duct hose to motor. Connect electrical connection. Lower vehicle and connect negative battery cable. Install air cleaner assembly.

Disconnect negative battery cable. Remove coolant recovery reservoir, cross brace bolts and brace, electrical center assembly and lay aside, ECM from mounting bracket lay aside. Remove air duct from blower motor assembly, blower motor mounting screws, lift blower motor assembly from position, electrical connection and blower motor assembly.

Connect electrical connection and blower motor. Install position motor assembly and mounting screws, air duct hose to blower, ECM from mounting bracket, electrical center assembly, cross brace bolts and brace, coolant recovery reservoir and connect negative battery cable.

OFF-VEHICLE SERVICE (ALTERNATOR BENCH CHECK)

Remove alternator from vehicle. Assure the carbon pile is turned off. The ground polarity of alternator and battery must be the same. The battery must be fully charged. Use a 30-500 ohm resistor between battery and "L" terminal. Rotate alternator pulley in clockwise direction. Slowly increase alternator speed and observe voltage.

Note. The battery must be fully charged when making this test.

If the voltage is uncontrolled and increases above 16 volts, replace the alternator. If the voltage is below 16 volts, increase speed, turn carbon pile "on" and adjust to obtain maximum amperage output. Maintain voltage above 13 volts. If output is within 15 amperes of rated output, the alternator is function properly. If output is not within 15 amperes of rated output, replace the alternator. Turn carbon pile "off" before disconnecting from battery.

Note. The CS-130 alternator cannot be disassembled, and must be serviced as a complete unit.

VEHICLES WITH CHARGE WARNING LIGHT

1. Visually check alternator belt and wiring. Turn ignition switch to ON position (engine not running). Charge light should come on. If light does not illuminate, go to step 2). If light comes on, go to step 4).
2. Disconnect harness connector at alternator. Using a jumper wire, connect terminal "L" of alternator harness connector to ground. If light now illuminates, repair or replace alternator.
3. If light still does not illuminate, check bulb. If bulb is okay, repair open circuit between jumper wire connected in step 2) and ignition switch. Reconnect alternator harness connector.
4. Start engine, and run at moderate speed. Charge light should go off. If charge light stays on, disconnect alternator wiring connector. If light goes off, repair or replace alternator. If light stays on, check for grounded wire between terminal "L" of alternator harness connector and charge indicator light.

VEHICLES WITH GAUGES

1. Visually check alternator belt and wiring. With ignition off, disconnect harness connector at alternator. Turn ignition on. Connect negative lead of a voltmeter to a good engine ground. Connect positive voltmeter lead, in turn, to terminals "I" and "L" of alternator harness connector.
2. Meter should indicate battery voltage at at least one terminal. If power appears at either or both terminals, reconnect harness connector, then continue with UNDER- OR OVERCHARGED BATTERY test. If power is not present at both terminals, repair open circuit between harness connector and ignition switch.

UNDER OR OVERCHARGED BATTERY

Note. Battery should be fully charged and in good condition before performing the following steps. If battery is not at (or near) a fully charged condition, or if its condition is questionable, substitute a known good battery before proceeding.

1. Perform tests under VEHICLES WITH CHARGE WARNING LIGHT or VEHICLES WITH GAUGES as appropriate. Connect positive voltmeter lead to positive battery post. Connect negative lead to negative battery post.
2. Start engine and run at moderate speed. If voltmeter indicates more than 16 volts, repair or replace alternator. If voltmeter indicates less than 16 volts, continue with CURRENT OUTPUT TEST.

CURRENT OUTPUT TEST

1. Connect an ammeter in series with alternator output cable. Connect positive voltmeter lead to positive battery post. Connect negative lead to negative battery post. CAUTION: Carbon-pile testing is part of this procedure. To avoid battery explosion, turn carbon pile OFF before connecting or disconnecting to and from vehicle battery.
2. Ensure carbon pile control knob is in OFF position. Connect carbon pile to battery. Start engine and run at moderate speed.
3. Turn on all accessories except for heated windshield on vehicles so equipped. Load battery with carbon pile to obtain maximum alternator output. Adjust carbon pile to maintain voltage at 13 volts or more.
4. If ammeter reading is within 15 amps of rated output, alternator is okay. If ammeter reading is not within 15 amps of rated output, repair or replace alternator.

ALTERNATOR OUTPUT TEST

Scheme 7

1. Mount alternator on test stand. Set test stand controls to turn alternator clockwise. Ensure ground polarity of alternator and battery are the same. Ensure battery is fully charged. Connect voltmeter, ammeter and carbon pile (in OFF position). Connect 30-500 ohm resistor between battery and terminal "L" of alternator. (Scheme 7)
2. Slowly increase alternator speed while observing voltmeter. If output is uncontrolled and increases to more than 16 volts, rotor coil is shorted and/or regulator is defective. A shorted rotor coil can cause regulator failure.
3. If voltage is less than 16 volts, increase speed and adjust carbon pile to obtain maximum output current. Maintain voltage at 13 volts. If output is within 15 amps of rated output, alternator is okay. If output is not within 15 amps of rated output, repair or replace alternator.

ROTOR TEST

Note. When disassembling alternator, carefully note locations of insulated and uninsulated screws.

Scheme 8

1. Scribe end frames to facilitate reassembly. Remove through bolts and separate end frames.
2. With ohmmeter set to its lowest range, measure coil resistance between slip rings. (Scheme 8) Replace rotor if coil resistance is not 1.7-3.0 ohms at 70°F (21°C).
3. With ohmmeter set to its highest range, check for grounds between either slip ring and rotor pole piece. (Scheme 8) If reading is not close to infinite, replace rotor. NOTE: Manufacturer recommends installing new bearing at slip ring end whenever alternator is reassembled.
4. To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. (Scheme 9) Remove retaining pin after tightening through bolts.

Scheme 9

CS144

1. Scribe end frames to facilitate reassembly. Remove through bolts and separate end frames. Remove stator lead attaching nuts and remove stator.
2. With ohmmeter set to its highest range, check that coil is not grounded to stator core. (Scheme 10) Ohmmeter should indicate infinite resistance. If ohmmeter does not indicate infinity, replace stator. Stator cannot be checked for opens or shorts with ohmmeter. NOTE: Manufacturer recommends installing new bearing at slip ring end whenever alternator is reassembled.
3. To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. (Scheme 9) Remove retaining pin after tightening through bolts.

Scheme 10

Scheme 11

1. Scribe end frames to facilitate reassembly. Remove through bolts and separate end frames. Remove stator. Connect an ohmmeter between grounded heat sink and any one of 3 grounded flat metal rectifier bridge terminal connectors; note reading. (Scheme 11)
2. Reverse meter leads. If both readings are the same, replace rectifier bridge. Repeat test between grounded heat sink and the other 2 flat metal terminal connectors. If readings are the same when leads are reversed at either connection, replace rectifier bridge.
3. Repeat test between insulated heat sink and its 3 flat rectifier bridge metal connectors. Replace rectifier bridge if test readings are the same when leads are reversed at any test connection. NOTE: Manufacturer recommends installing new bearing at slip ring end whenever alternator is reassembled.
4. To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. (Scheme 9) Remove retaining pin after tightening through bolts.

OVERHAUL

Note. Replacement parts are not available for CS121 and CS130 alternators. If alternator is defective, a new unit must be installed. CS144 alternators without auxiliary terminals for heated windshields may be disassembled for repair.

1. Scribe end frames to facilitate reassembly. Remove through bolts and separate end frames. Unsolder brush connections. Remove attaching screws and connectors. Remove regulator and brush holder. Clean new brushes with soft dry cloth.
2. Put brushes in holder and hold with brush retaining pin. (Scheme 9) Install brush holder into alternator by reversing removal procedure. To reassemble alternator, reverse disassembly procedure. Remove brush retainer pin after tightening through bolts.

Note. Manufacturer recommends installing new bearing at slip ring end whenever alternator is reassembled.

1. Scribe end frames to facilitate reassembly. Remove through bolts and separate end frames. Remove shaft nut while holding rotor with hex wrench inserted into shaft end. Push rotor from housing. Remove retainer plate and press bearing out. On some alternators, drive end bearing cannot be replaced.
2. To install new bearing, press against outer race until bearing seats. Bearing is sealed; no added lubricant is required. Assemble retainer and press rotor into end frame. Tighten shaft nut to 40-80 ft. lbs. (54-108 N.m). NOTE: Manufacturer recommends installing new bearing at slip ring end whenever alternator is reassembled.
3. To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. (Scheme 9) Remove retaining pin after tightening through bolts.

TORQUE SPECIFICATIONS

FASTENER TORQUE SPECIFICATIONS