Instruments - Generator Light Flickers, Pulse Wipers ON
89Chevy29GMC NUMBER: 89-T-85
GROUP: 6D - Engine Electrical
DATE: July, 1989
CORPORATE
NUMBER: 966402R
SUBJECT: GENERATOR LIGHT FLICKER DURING PULSE WIPER OPERATION
MODELS: 1988-89 S/T WITH 2.8L OR 4.3L ENGINE
The generator light flicker condition in the 1988 and 1989 S/T instrument panel during pulse wiper switch operation can be caused by negative voltage transients from the wiper motor There is no possibility of a system failure as a result of this condition. The effect of this condition is that the generator light will turn on for 80 milliseconds (if gages, the voltage drop on the voltmeter lasts 2.5 seconds). This causes no harm to the generator or other electrical components. Subject condition can be eliminated by installing a diode (industry part number 1N4003) or diode/connector kit (diode kit part number 12085207) in the brown wire at the generator connector (circuit 25 at connector C118). See the following pages in the 1988 and 1989 S/T Electrical Wiring Diagrams for circuit 25, connector C188 locations:
1988 4.3L: Section C - Page 24
1988 2.8L: Section C - Page 22
1989 4.3L: Page 40
1989 2.8L: Page 39
PARTS INFORMATION:
Quantity Part Number Description
1 12085207 Diode
OR
1 *1N4003 Diode
*This part available locally.
Parts are currently available from GMSPO.
INSTALLATION PROCEDURE:
1. Disconnect the battery.
2. Remove the connector from the generator.
3. Peel back the black plastic conduit covering the wires.
4. If installing diode 1N4003: cut out a section of the brown wire that matches the length of the diode.
4A. A diode/connector kit is also available (GMSPO diode kit part number 12085207). If using the kit cut out approximately four inches of the brown wire, following crimping and soldering instructions in the kit. Spiral tape the solder joints and tuck the wire back into the conduit away from the generator Secure the diode/connector to the outside of the conduit with electrical tape.
5. Solder in diode with the banded end toward the generator.
6. Tape the solder and diode.
7. Reinstall the black plastic conduit.
8. Reconnect connector to the generator.
9. Reconnect battery.
This procedure will not affect the operation of the generator light during the bulb check at the beginning of the start cycle. For vehicles repaired under warranty use
Labor operation T7990
Labor time .4 Hr