Alternator & Regulator Jeep Wrangler I

DESCRIPTION

Two types of alternators are used. The SI (Systems Integral) series alternator is a Delcotron type and is used in the Grand Wagoneer and Wrangler. This series is serviceable, with an internal voltage regulator that is not adjustable. The CS (Charging System) series alternator is used in the Cherokee, Comanche and Wagoneer. This series is a sealed unit and is not serviceable. It has a solid state internal voltage regulator and is not adjustable.

ALTERNATOR APPLICATION

CS SERIES

The solid state voltage regulator varies voltage to compensate for current load and engine 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. If system voltage is too high or too low, voltage regulator will turn ON charge indicator light while engine is running.

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 battery output terminal.

Alternator field current is supplied through a diode trio 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 (ON-VEHICLE)

Note. Before testing, check all terminals connections. Check alternator mounting bolts and drive belt tension. Ensure battery is fully charged.

CS SERIES - OVER/UNDERCHARGED BATTERY (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-wire connector from alternator. Turn ignition on with engine off. 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.

CS SERIES - 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.

CS SERIES - ALTERNATOR OUTPUT TEST

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.

Scheme 1

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 and leave all wiring leads connected. Connect a voltmeter from alternator BAT terminal to ground. Voltmeter should read 12.5 volts. Backprobe with voltmeter between No. 1 terminal and ground. Voltmeter should read 2-4 volts. (Scheme 1)
3. Backprobe with voltmeter between No. 2 terminal and ground. Voltmeter should read 12.5 volts. A zero reading on any connection indicates an open between connection and battery. Opens in the No. 2 lead will prevent alternator from turning on.

Scheme 2

1. Connect an ammeter or alternator tester 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.
2. Output must be within 10 amps of rated output stamped on alternator. If not, ground field winding by inserting a screwdriver into test hole, touching tang to alternator case. (Scheme 2) Repeat step 1).
3. If output 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.

Note. DO NOT insert screwdriver more than 1" into end frame or

CS SERIES BENCH TESTING

Note. There are no internal checks for CS series alternators. Manufacturer does not recommend disassembling and servicing CS alternators. Install a new unit if alternator is defective.

Rotor Field Winding Test

1. Separate alternator halves. To check for grounds, attach ohmmeter leads to rotor shaft and one slip ring (test both slip ring circuits). If reading is not infinity, replace rotor.
2. To test for open field, touch one ohmmeter lead to each slip ring. Resistance should measure about 2.2-3.0 ohms. If not, replace rotor.

Stator Test

Disconnect 3 stator winding leads from rectifier bridge and remove stator from housing. Measure resistance between stator leads. If reading is not infinity on all leads as tested, replace stator. Connect ohmmeter leads to any stator lead and to stator frame to check for grounded circuit. Ohmmeter reading should be infinity.

Diode Trio Test

Remove diode trio from end frame. Connect an ohmmeter probe to brush terminal and other probe to one of the stator winding terminals. Check resistance on lowest range scale. Note reading and reverse leads. If readings are the same, replace diode trio. Check other 2 stator terminals of diode trio in same manner. Connect probes between any 2 stator terminals, if resistance is zero, diode is shorted and must be replaced.

Rectifier Bridge Test

1. Position ohmmeter with one lead touching grounded heat sink and other lead touching flat metal of diode on one of 3 terminals. Observe reading and reverse test lead connections.
2. If both readings are the same, replace rectifier bridge. A good bridge will give a high and low reading. Test all terminals (6 tests with insulated heat sink).
3. Connect ohmmeter leads to insulated heat sink and to 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 test light to check bridge. Replace diode trio or rectifier bridge if one pair of readings is the same.

OVERHAUL

Note. Refer to exploded view in (Scheme 3) for alternator overhaul. Exploded view of CS series alternator not available from manufacturer.

DISASSEMBLY & INSPECTION - SI SERIES

1. Scribe housings for reassembly reference. Use care in separating halves so as not to lose brush springs or allow brushes to contact lubricant. If brush spring is lost of brushes become contaminated, brush assembly must be replaced. Clean all metal parts except bearings, stator and rotor with electrical cleaning fluid only.
2. Inspect brush holder insulating sleeve/washers for wear. Inspect rotor slip rings. They may be cleaned with 400 grit or finer polishing cloth. Excessively scored slip rings may be lathe turned to .002" (.05 mm) maximum indicator reading. Slip rings are not replaceable and excessive damage will require rotor replacement.
3. Inspect brushes for wear, replacing if more than half worn. When installing brushes, use toothpick or similar device to retain brushes in holder until alternator assembly is completed.

Scheme 3

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• TROUBLE SHOOTING - BASIC PROCEDURES