System Diagnosis - Charging System - Delcotron Type SI Integral

If a condition of a dimly lit No Charge indicator lamp occurs under heavy electrical load on 1982 and some 1983 Cadillac Brougham and Deville models with Digital Fuel Injection, it may be caused by insufficient filtering of the No Charge indicator bulb.
This condition is not caused by a low charging rate but, by the alternator charging at near maximum capacity, with alternator voltage output in excess of battery voltage. This causes a voltage potential difference across the indicator lamp terminals, resulting in a dim bulb glow.
This condition can be checked by thoroughly testing the charging system. If all systems are satisfactory, the indicator lamp should be removed and a filter (GM part No. 25076102) installed over the bulb. The bulb should then be reinstalled.

Fig. 4 Grounding field windings:

UNDERCHARGED BATTERY
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. 4. Do not insert screwdriver deeper than one inch since tab is usually located within 3-4 inch of casing surface.
8. If reading is within 10 amps of rated output, regulator must be replaced. 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. 5 Testing voltage regulator:

IN-VEHICLE VOLTAGE REGULATOR TEST
1. Connect voltmeter and fast charger to 12 volt battery as shown in Fig. 5.
2. Connect regulator and test light as shown, observing battery polarity.
3. Test light should be on.
4. Turn on fast charger and slowly increase charge rate. Observe voltmeter, light should go out at a voltage regulator setting of 13.5---16.0 volts.
The test light is connected into the circuit, exactly as the rotor is when the regulator is inside the generator. The regulator shuts off the current to the test light when the regulator setting is reached. This voltage will vary with changes in temperature.