System Diagnosis - Delcotron SI (Type 100) Integral Charging Systems

UNDERCHARGED BATTERY
Preliminary Checks
1. Ensure accessories have not been left on for extended periods, causing undercharged condition.
2. Check alternator drive belt for proper tension.
3. Check battery for internal defects.
4. Check all wiring connections for corrosion or looseness. Repair or replace as necessary.
5. With ignition switch On and alternator leads connected, connect voltmeter from:
a. Alternator ``BAT'' terminal and ground.
b. Alternator No. 1 terminal and ground.
c. Alternator No. 2 terminal and ground.
6. If reading in step 5 is zero volts, check for open between voltmeter connection and battery.

Fig. 7 Grounding field windings:

Troubleshooting Procedure
1. Disconnect battery ground cable.
2. Disconnect wire at ``BAT'' terminal of alternator, connect ammeter, positive lead to ``BAT'' terminal and negative lead to wire.
3. Connect battery ground cable.
4. Turn on all accessories, then connect a carbon pile regulator across battery.
5. Operate engine at moderate speed, adjust carbon pile regulator to obtain maximum current output.
6. If ammeter reading is within 10 amps of rated output, alternator is not at fault. Alternator rated output is stamped on alternator frame.
7. If ammeter reading is not within 10 amps of rated output, ground field winding by inserting screwdriver in end frame hole, contacting tab, Fig. 7. Do not insert screwdriver deeper than one inch, as tab is usually located within 3/4 inch of casing surface.
8. If reading is within 10 amps of rated output, check field winding, diode trio, rectifier bridge and voltage regulator. If reading is not within limits, check field winding, diode trio, rectifier bridge and stator.
9. Turn off all accessories and disconnect ammeter and carbon pile regulator.

Fig. 8 Testing brush clip:

OVERCHARGED BATTERY
1. Remove alternator from vehicle and separate end frames as outlined under ``Alternator Disassembly.''
2. Check field winding. If shorted, replace rotor and test regulator.
3. Connect ohmmeter from brush clip to end frame, set meter on low scale and note reading, Fig. 8.
4. Reverse leads, if both readings are zero, remove screw from brush clip and inspect sleeve and insulator.
5. If sleeve and insulator are in good condition, then regulator is at fault and must be replaced.




ALTERNATOR NOISE
Alternator noise may be caused by a loose drive pulley, loose mounting bolts, worn or dirty bearings, defective diodes or a defective stator. Inspect all components and replace as necessary.

Fig. 9 Charging system diagnosis chart:

CHARGING SYSTEM DIAGNOSIS
For charging system diagnosis, refer to ``Charging System Diagnosis Chart,'' Fig. 9.

Fig. 10 Voltage regulator test:

TRANSISTORIZED VOLTAGE REGULATOR TEST
1. Connect a suitable voltmeter and fast charger to battery, Fig. 10.
2. Turn ignition on and slowly increase charge rate, while observing voltmeter and generator warning light.
3. The generator warning light should dim when voltmeter reads 13.5---16.0 volts. If light does not dim at specified voltage, replace voltage regulator.