Alternator & Regulator — Buick Roadmaster VIII (1991-1996)

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 terminal "L" of the regulator. This connection provides initial excitation at start-up.

Three other regulator terminals, "P", "I" and "S", are provided for option-al 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.

ON-VEHICLE TESTING

CAUTION

When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in the GENERAL INFORMATION section before disconnecting battery.

VEHICLES WITH CHARGE/CHECK GAUGES WARNING LIGHT

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).
Turn ignition off. Disconnect harness connector at alternator. Using a jumper wire, connect terminal "L" of alternator harness connector to ground. Turn ignition on. If light illuminates, repair wiring connections or replace alternator.
If light still does not illuminate, check circuit No. 25 (Brown wire) and bulb circuits for an open circuit. If Brown wire and bulb circuits are okay, replace instrument cluster.
Start and run engine at moderate speed. Charge light should go off. If charge light stays on, turn ignition off. Disconnect alternator wiring connector. Turn ignition on. If light does not light, replace alternator. If light stays on, check for short to ground on circuit No. 25 (Brown wire) between terminal "L" of alternator harness connector and charge indicator light.

VEHICLES WITH GAUGES

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.
Meter should indicate battery voltage. If power appears at either or both terminals, reconnect harness connector, then continue with «UNDERCHARGED OR OVERCHARGED BATTERY»(/buick/roadmaster/viii-1991-1996/remont/charging-system/#alternator-regulator__undercharged-or-overcharged-battery) test. If power is not present at both terminals, repair open circuit between harness connector and ignition switch.

UNDERCHARGED OR OVERCHARGED BATTERY

Note. Ensure battery is 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.

On all models except Achieva, perform either the test procedures under «VEHICLES WITH CHARGE/CHECK GAUGES WARNING LIGHT»(/buick/roadmaster/viii-1991-1996/remont/charging-system/#alternator-regulator__vehicles-with-chargecheck-gauges-warning-light) or «VEHICLES WITH GAUGES»(/buick/roadmaster/viii-1991-1996/remont/charging-system/#alternator-regulator__vehicles-with-gauges) as appropriate. Disconnect alternator connector. Turn ignition on. Using a DVOM, connect positive voltmeter lead to Pink/Black or Brown wire and negative lead to ground.
Battery voltage should be present. If battery voltage is not present, check and repair circuit No. 639 (Pink/Black) or circuit No. 250 (Brown wire) for an open or short to ground. Check fuses, replace if necessary.
Connect positive voltmeter lead to battery terminal of alternator and negative lead to ground. Battery voltage should be present. If battery voltage is not present, check and repair Black/Red or Red wire from battery to alternator for an open or short to ground.
On models with 3.3L engine, connect positive voltmeter lead to Red wire and negative lead to ground. Battery voltage should be present. If battery voltage is not present, check for an open in circuit No. 2 (Red wire) and fusible link for an open.
With engine running at fast idle speed and all accessories turned off, voltmeter should read greater than 12 volts and less than 16 volts. If voltmeter indicates greater than 16 volts or less than 12 volts, repair or replace alternator.
On Achieva, disconnect alternator battery terminal and alternator electrical connector. Turn ignition on. Measure voltage between terminal "L" (Brown wire) and ground. Battery voltage should be present.
If battery voltage is not present, check and repair open in circuit No. 25 (Brown wire) and circuit No. 39 (Pink/Black wire). If battery voltage is present, turn ignition on. Measure voltage between terminal "F" (Pink/Black wire) and ground.
Battery voltage should be present. If battery voltage is not present, check fuses and repair open in circuit No. 439 (Pink/Black wire). If battery voltage is present, with ignition on, measure voltage between terminal "S" (Red wire) and ground.
Battery voltage should be present. If battery voltage is not present, repair open in circuit No. 2 (Red wire). If battery voltage is present, with ignition switch on, measure voltage between BAT terminal (Red wire) and ground.
Battery voltage should be present. If battery voltage is not present, repair open in circuit No. 2 (Red wire). If battery voltage is present, reconnect alternator electrical connector.
Turn all accessories off. With engine running, measure voltage between BAT terminal (Red wire) and ground. Voltage should be less than 16 volts. If voltage is greater than 16 volts, repair or replace alternator. If voltage is okay, see «CURRENT OUTPUT TEST»(/buick/roadmaster/viii-1991-1996/remont/charging-system/#alternator-regulator__current-output-test) .

CURRENT OUTPUT TEST

CAUTION

DO NOT run engine with alternator output terminal disconnected from battery.

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 to or disconnecting from vehicle battery.
Ensure carbon pile control knob is in OFF position. Connect carbon pile to battery. If voltage is greater than 16 volts, repair or replace alternator. If voltage is less than 16 volts, go to next step.
Start engine and run at moderate speed. 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 greater than 13 volts.
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

CAUTION

Carbon pile testing is part of this procedure. To avoid battery explosion, turn carbon pile OFF before connecting to or disconnecting from test stand battery.

Scheme 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 1)
Slowly increase alternator speed while observing voltmeter. If output is uncontrolled and increases to greater than 16 volts, rotor field coil is shorted and/or regulator is defective. A shorted rotor field coil can cause regulator failure.
If voltage is less than 16 volts, increase speed and adjust carbon pile to obtain maximum output current. Maintain voltage greater than 13 volts. If output is within 15 amps of rated output, alternator is okay. If output is not within 15 amps of rated output, replace alternator.

ROTOR TEST

Note. Install new bearing at slip ring end whenever alternator is reassembled. When disassembling alternator, carefully note locations of insulated and uninsulated screws.

CS144 (Without Auxiliary Phase Terminals)

Scribe end frames to facilitate reassembly. Remove through bolts and separate end frames.
With ohmmeter set to its lowest range, measure coil resistance between slip rings. (Scheme 2) Replace rotor if coil resistance is not 2.1-2.4 ohms at 70°F (21°C).
With ohmmeter set to its highest range, check for grounds between either slip ring and rotor pole piece. (Scheme 2) If reading is not close to infinite, replace rotor.
To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. (Scheme 3) Remove retaining pin after tightening through bolts.

Scheme 2

Scheme 3

STATOR TEST

Note. Install new bearing at slip ring end whenever alternator is reassembled.

Scribe end frames to facilitate reassembly. Remove through bolts and separate end frames. Remove stator lead attaching nuts and remove stator.
With ohmmeter set to its highest range, ensure coil is not grounded to stator core. (Scheme 4) Ohmmeter should indicate infinite resistance. If ohmmeter does not indicate infinity, replace stator. Stator cannot be checked for opens or shorts with ohmmeter.
To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. (Scheme 3) Remove retaining pin after tightening through bolts.

Scheme 4

RECTIFIER BRIDGE TEST

Note. Install new bearing at slip ring end whenever alternator is reassembled.

Scheme 5

Scheme 5: CS144 (Without Auxiliary Phase Terminals)

Scribe end frames to facilitate reassembly. Remove through bolts and separate end frames. Remove stator. Connect ohmmeter between grounded heat sink and any of 3 grounded flat metal rectifier bridge terminal connectors and note reading. (Scheme 5)
Reverse meter leads. If both readings are the same, replace rectifier bridge. Repeat test between grounded heat sink and other 2 flat metal terminal connectors. If readings are the same when leads are reversed at either connection, replace rectifier bridge.
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.
To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. (Scheme 3) Remove retaining pin after tightening through bolts.

TROUBLE SHOOTING

Note. Also see TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

ALTERNATOR (AUTOMATIC TRANSAXLE - 3.4L)

CAUTION

Failing to disconnect the battery cable may result in an injury. If a tool is shorted at the alternator lead, the tool will heat enough to cause a skin burn.

Removal

Remove air cleaner. Disconnect the negative battery cable. Disconnect coolant recovery tank and position aside. Remove the serpentine belt. Raise vehicle and suitably support it.
Remove tire and wheel assemblies. Remove right engine splash shield upper retaining clips and pull down shield. Remove front exhaust pipe and converter assembly.
Remove steel drive axle shield retaining screws and shield. Remove ball joint nut and separate control arm. Remove right drive axle from transaxle.
Remove steering gear heat shield retaining screws and shield. Disconnect knock sensor electrical connector. Remove alternator cooling duct. Remove alternator rear brace bolt. Access bolt through left wheel opening using a 4 foot extension.
Loosen alternator rear brace bolt nut at engine. Access nut through right wheel well behind alternator. Remove power steering clip and upper alternator stud nut.
Disconnect alternator electrical connectors from alternator. Remove nut and disconnect battery positive lead from alternator output ("BAT") terminal. Remove alternator assembly upper stud and lower bolt/screw. Remove alternator.

Installation

Install alternator. Connect alternator electrical connectors to alternator. Connect the battery positive lead and nut to alternator output ("BAT") terminal. Connect alternator to mounting bracket and loosely install mounting bolt. NOTE: If replacement alternator does not fit, remove adhesive- backed shim from alternator bracket.
Install alternator rear brace and bolt, including cooling duct bracket. Access bolt through left wheel opening using a 4 foot extension. Tighten alternator lower mounting bolt to 37 ft. lbs. (50 N.m). Tighten alternator upper mounting stud to 18 ft. lbs. (25 N.m). Access the alternator rear brace nut through the right wheel well behind alternator and tighten to 37 ft. lbs. (50 Nm). Tighten alternator rear brace bolt to 18 ft. lbs. (25 N.m).
Install upper alternator stud nut and power steering clip. Install alternator cooling duct. Install knock sensor electrical connector.
Install steering gear heat shield and retaining screws. Install right drive axle to transaxle. Install right control arm and ball joint. Install steel drive axle shield and retaining screws.
Install front exhaust pipe and converter assembly. Install right engine splash shield using upper retaining clips. Install both tire and wheel assemblies. Lower vehicle.
Install serpentine belt. Install coolant recovery tank. Connect negative battery cable. Install air cleaner assembly.

Note. Adjust transaxle fluid if necessary.

Remove air cleaner.

CAUTION

Failing to disconnect the battery cable may result in an injury. If a tool is shorted at the alternator lead, the tool will heat enough to cause a skin burn.

Disconnect the negative battery cable. Remove the serpentine belt, power steering clip and upper alternator stud nut. Raise vehicle and suitably support.
Remove right front tire and wheel assembly. Remove right engine splash shield upper retaining clips and pull down shield. Remove plastic outboard drive axle shield. Remove alternator rear brace retaining bolt and nut.
Remove alternator rear brace, including cooling duct bracket. Disconnect alternator electrical connectors from alternator, battery positive lead and nut from alternator output ("BAT") terminal.
Remove ball joint nut and separate control arm. Remove right drive axle at transaxle, steel outboard drive axle shield, rear motor mount bracket brace retaining bolts with steel inboard drive axle shield attached. Remove alternator retaining upper stud, lower bolt and alternator.

Connect alternator to mounting bracket and loosely install mounting bolt and stud. Tighten alternator lower mounting bolt to 37 ft.lbs. (50 N.m) and upper alternator stud to 18 ft.lbs. (25 N.m). NOTE: If replacement alternator does not fit, remove adhesive- backed shim from alternator bracket.
Install rear motor mount bracket brace retaining bolts with steel inboard drive axle shield attached. Install steel outboard drive axle shield, right drive axle at transaxle and ball joint nut.
Connect alternator electrical connectors to alternator. Connect battery positive lead and nut to alternator output ("BAT") terminal. Install alternator rear brace and tighten rear brace bolt to 18 ft.lbs. (25 N.m). and tighten rear brace nut to 37 ft.lbs. (50 N.m) bolt. This includes the cooling duct bracket.
Install plastic outboard drive axle shield, right engine splash shield and upper retaining clips, right front tire and wheel assembly. Lower vehicle. Install power steering clip, upper alternator stud nut and serpentine belt. Connect negative battery cable. Install air cleaner.

Disconnect negative battery cable. Raise vehicle and suitably support. Remove alternator rear brace retaining bolt and nut, including cooling duct bracket. Remove alternator rear brace.

Install alternator rear brace, rear brace retaining bolt and nut, including cooling duct bracket and tighten. Tighten the alternator rear brace bolt to 18 ft.lbs. (25 N.m). Tighten the alternator rear brace nut to 37 ft.lbs. (50 N.m). Lower vehicle and connect negative battery cable.

OVERHAUL

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

BRUSHES & REGULATOR

Note. Install new bearing at slip ring end whenever alternator is reassembled.

CS144

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.
Put brushes in holder and hold with brush retaining pin. (Scheme 3) Install brush holder into alternator by reversing removal procedure. To reassemble alternator, reverse disassembly procedure. Remove brush retainer pin after tightening through bolts.

DRIVE-END BEARING

Note. Install new bearing at slip ring end whenever alternator is reassembled.

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.
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).
To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. (Scheme 3) Remove retaining pin after tightening through bolts.

TORQUE SPECIFICATIONS

Application	Ft.Lbs. (N.m)
Alternator Rear Bracket Bolt	18 (25)
Alternator Rear Brace Nut	37 (50)
Alternator Lower Mounting Bolt	37 (50)
Upper alternator Stud	18 (25)
INCH LBS. (N.m)
Nut To alternator Output	71 (8)