ALTERNATOR - DELCO W/INTEGRAL REGULATOR

1988 Jeep Cherokee

1988 Alternators & Regulators

DELCO-REMY WITH INTEGRAL REGULATOR

Jeep

DESCRIPTION

There are 2 types of alternators used on these vehicles. The

12SI and 17SI series (Systems Integral), means alternator with builtin

regulator. All 12SI alternators have "Y" stator windings, while all

17SI have delta windings.

The CS130 (Charging System) alternators have a high amperage

output. This alternator does not have a diode trio.

IDENTIFICATION

Fig. 1: Alternator Terminal Identification & Locations

"S" terminal is optional on CS130.

OPERATION

CS SERIES

Regulator voltage varies to compensate for temperature.

Voltage is regulated by controlling rotor field current. Regulator

switches rotor field current "on" and "off" at a fixed frequency of

approximately 400 cycles per second.

By controlling "on" and "off" time correct system voltage can

be obtained. During high speeds "on" time may be 10 percent and "off"

time 90 percent. During low speeds with high electrical loads, "on"

time may be 90 percent and "off" time 10 percent.

SI SERIES

A rectifier bridge, connected to stator windings, contains 6

diodes (3 positive and 3 negative) molded into an assembly. This

rectifier bridge changes stator AC voltage into DC voltage, which

appears at output terminal.

Alternator field current is supplied through a diode trio

which is also connected to stator windings. A capacitor is mounted to

end frame, protecting rectifier bridge and diodes from high voltage

and suppressing radio interference noise.

TROUBLE SHOOTING

NOTE: See the TROUBLE SHOOTING - BASIC PROCEDURES article

in the GENERAL TROUBLE SHOOTING section.

TESTING

PRELIMINARY INFORMATION

NOTE: Before making electrical checks, visually inspect all

terminals for clean, tight connections. Check alternator

mounting bolts and drive belt tension. Battery must be in

good condition to test charging system.

TESTING (ON-VEHICLE)

CS SERIES

Over/Undercharged Battery (W/ STandard Instruments)

1) If an overcharging condition is suspected, run engine at a

moderate speed. Connect a voltmeter across battery terminals. If

voltmeter indicates more than 16 volts, replace alternator.

2) If an undercharging condition is suspected, disconnect

2

Connect a voltmeter between terminal "L" in wiring harness and ground.

Record reading.

3) If terminal "I" is used, connect voltmeter between

terminal "I" and ground. Record reading. If voltmeter reads battery

voltage, circuits are okay. If voltmeter reads zero, this indicates an

open circuit between terminal checked and battery. Repair as

necessary.

Overcharged Battery (W/ Gauges)

If an overcharging condition is suspected, run engine at a

moderate speed. Connect a voltmeter across battery terminals. If

voltmeter indicates more than 16 volts, replace alternator.

Alternator Output Test (W/ Standard Instruments Or Gauges)

1) Run engine at moderate speed, all electrical accessories

off. Measure voltage across battery, if above 16 volts, replace

alternator.

2) Connect an ammeter in circuit at "BAT" terminal of

alternator. Turn on all available accessories. Connect a battery load

tester across battery. Operate engine at 2000 RPM and adjust battery

load tester as required to obtain maximum current output while

maintaining 13 volts or more.

3) Output must be within 15 amps of rated output stamped on

alternator. If output is not within 15 amps of rated output, replace

alternator.

wire connector from alternator. Turn ignition on with engine off.

SI SERIES

Overcharged Or Undercharged Battery

1) If an overcharging condition is suspected, attach a

voltmeter across battery terminals. Run engine at a moderate speed

with all accessories off. If voltmeter reads 15.5 volts or more,

remove alternator for repair.

2) If an undercharging condition is suspected, turn ignition

on. Connect a voltmeter from alternator "BAT" terminal to ground.

Voltmeter should read 12 volts. Connect voltmeter between No. 1

terminal and ground. Voltmeter should read one volt or more.

3) Connect voltmeter between No. 2 terminal and ground.

Voltmeter should read 12 volts. A zero reading on any connection

indicates an open between connection and battery. Opens in the No. 2

lead may be between terminals at the crimp between harness wire and

terminal, or in wire.

Alternator Output Test

1) Connect an ammeter in circuit at "BAT" terminal of

alternator. Turn on all available accessories. Connect a carbon pile

across battery. Operate engine at 2000 RPM and adjust carbon pile as

required to obtain maximum current output.

2) Ampere output must be within 10 amps of rated output. If

output is not within 10 amps of rated output, ground field winding by

inserting a screwdriver into test hole. Repeat step 1).

3) If output is increases to within 10 amps of rated output

with field grounded, regulator is defective. If output remains below

10 amps of rated output, check field winding, diode trio, rectifier

bridge, and stator.

CAUTION: Tab is within 3/4" of casting surface. DO NOT force tool

beyond 1" into end frame. If test hole is not accessible,

proceed to BENCH TESTING.

BENCH TESTING

NOTE: There are no internal checks for CS series alternators.

SI SERIES

Rotor Field Winding Test

1) To check for grounds, attach ohmmeter leads to shaft and

slip ring (each ring in turn). If reading is not infinity, replace

rotor.

2) To test for open field, attach ohmmeter leads to each slip

ring. Resistance should measure about 2.4

1.7

Fig. 2: Rotor Bench Test For Open or Short Circuit

Stator Test

NOTE: Delco 17SI alternator has delta stator windings and cannot

be checked for open circuit.

1) For 12SI series alternator, measure resistance between

stator leads. See Fig. 3. If reading is not infinity, replace stator.

2) On all models, connect ohmmeter leads to any stator lead

and to stator frame. Ohmmeter reading should be infinity. See Fig. 3.

Fig. 3: Testing Stator for Open or Grounded Circuits

Diode Trio Test

1) Remove diode trio from end frame. Connect an ohmmeter to

single connector and to one of the 3 connectors. See Fig. 4. Note

reading and reverse leads. If readings are the same, replace diode

trio.

2) A good diode trio will give a high and low reading. Repeat

tests between single connector and each of the 3 connectors. Connect

ohmmeter to each of the 3 connectors. If any readings are zero,

replace diode trio.

NOTE: Before replacing diode trio, also check rectifier bridge.

DO NOT use high voltage, such as 110

testing diode trio.

Fig. 4: Bench Testing Diode Trio

Rectifier Bridge Test

1) Position ohmmeter with one lead touching grounded heat

sink and the other lead touching flat metal on one of the 3 terminals

or threaded studs. Observe reading and reverse test lead connections.

See Fig. 5.

2) If both readings are the same, replace rectifier bridge. A

good bridge will give a high and low reading. Retest all terminals (6

tests with insulated heat sink).

3) Connect test leads to insulated heat sink and one edge of

the 3 terminals. Observe reading and reverse connections. Repeat test

on all terminals (6 tests with insulated heat sink).

4) When all 12 tests have been made, testing is complete. DO

NOT use high voltage light to check bridge. DO NOT replace diode trio

or rectifier bridge unless at least one pair of readings is the same

(with leads reversed).

Fig. 5: Bench Testing Rectifier Bridge

2.8 ohms on 12SI series, or  2.1 ohms on 17SI series. If not, replace rotor. volt test light, when

OVERHAUL

NOTE: There are no overhaul procedures for CS130 alternators.

INSPECTION

Wash all metal parts except bearings, stator and rotor.

Inspect rotor slip rings. They may be cleaned with 400 grit or finer

polishing cloth, while rotor is being rotated. Slip rings may be lathe

turned to .002" (.05 mm) maximum indicator reading.

Slip rings are not replaceable. Excessive damage will require

rotor replacement. Inspect brushes for wear, replacing them if more

than 50% worn.

Fig. 6: Exploded View of Model 12SI Alternator

Courtesy of General Motors Corp.

Fig. 7: Exploded View of Model 17SI Alternator

Courtesy of General Motors Corp.

SPECIFICATIONS

ALTERNATOR OUTPUT FOR CS SERIES

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Stamped Rating Amps @ 14v Engine RPM

85 .................. 30 ..................... 1600

100 ................. 36 ..................... 1600

105 ................. 42 ..................... 1600

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ALTERNATOR OUTPUT FOR SI SERIES

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Stamped Rating Amps @ 14v Engine RPM

66 .................. 23 ..................... 1600

78 .................. 30 ..................... 1600

94 .................. 30 ..................... 1600

120 ................. 50 ..................... 1600

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