AM BAND RADIO INTERFERENCE WITH WINDSHIELD WIPERS OPER.

SUBJECT: AM BAND RADIO INTERFERENCE WHEN WINDSHIELD WIPERS ARE OPERATING OR SECONDARY IGNITION SYSTEM NOISE WITH ENGINE RUNNING (INSTALL THREE ADDITIONAL GROUND CIRCUITS)

MODELS: 1997-98 CHEVROLET VENTURE 1997-98 OLDSMOBILE SILHOUETTE 1997-98 PONTIAC TRANSPORT

CONDITION:

SOME OWNERS MAY COMMENT THAT THERE IS RADIO INTERFERENCE (STATIC OR BUZZING SOUND) ON THE "AM" BAND WHEN THE WINDSHIELD WIPER ARMS ARE MOVING. IN ADDITION, SOME OWNERS MAY COMMENT THAT THERE IS A BUZZING TYPE SOUND COMING FROM THE RADIO WHEN THE ENGINE IS RUNNING. THEY MAY STATE THAT THIS SOUND INCREASES AND DECREASES WITH ENGINE SPEED (RPM). THERE IS NO INTERFERENCE ON THE "FM" BAND.

CORRECTION:

ADDITIONAL GROUND CIRCUITS ARE REQUIRED BETWEEN THE WINDSHIELD WIPER SYSTEM AND THE VEHICLE BODY, THE ENGINE COMPARTMENT HOOD AND THE FRONT END SHEET METAL, AND THE RADIATOR SUPPORT AND THE ENGINE.

DIAGNOSIS -

VERIFY THE CONDITION WITH THE VEHICLE OUTDOORS AND AWAY FROM ANY BUILDINGS OR OVERHEAD ELECTRICAL LINES.

1. WITH THE HOOD CLOSED, TURN IGNITION SWITCH TO THE "ACCESSORY" POSITION.

2. WITH THE RADIO SET ON THE "AM" BAND AND NORMAL VOLUME, VERIFY THAT NO INTERFERENCE IS PRESENT WHILE THE WIPERS ARE TURNED "OFF".

-- IF INTERFERENCE IS PRESENT, IT IS ORIGINATING FROM A SOURCE OTHER THAN THE WIPER SYSTEM. SEE THE SERVICE MANUAL FOR ADDITIONAL DIAGNOSIS.

-- IF NO INTERFERENCE IS PRESENT, TURN THE WIPER SWITCH TO THE LOW OR HIGH POSITION. IF INTERFERENCE IS PRESENT WHEN THE WIPER ARMS ARE MOVING, TURN THE WIPER SWITCH TO THE OFF POSITION. IF THE INTERFERENCE STOPS WHEN THE WIPER ARMS "PARK" OR STOP MOVING, THREE ADDITIONAL GROUND WIRE CIRCUITS ARE REQUIRED.

3. WITH THE TRANSMISSION IN PARK AND THE PARKING BRAKE SET, START THE ENGINE AND ALLOW TO IDLE.

-- IF INTERFERENCE IS PRESENT, SLIGHTLY INCREASE THE ENGINE RPM'S. IF THE NOISE SPEEDS UP WITH THE INCREASE IN ENGINE SPEED AND THEN SLOWS DOWN WHEN THE ENGINE IS ALLOWED TO RETURN TO IDLE, THREE ADDITIONAL GROUND WIRE CIRCUITS ARE REQUIRED.

-- IF NO INTERFERENCE IS PRESENT, SEE THE SERVICE MANUAL FOR ADDITIONAL DIAGNOSIS.

SERVICE PROCEDURE:

1. RECORD RADIO STATION PRE-SETS.

2. DISCONNECT NEGATIVE BATTERY CABLE.

BRAIDED GROUND STRAP NUMBER 1 (WIPER MOTOR BRACKET TO BODY)

1. OPEN HOOD AND REMOVE THE WIPER MODULE ASSEMBLY PLASTIC COVER. FOR IMPROVED ACCESS TO THE FENDER ATTACHMENT LOCATION, REMOVE THE FUSE RELAY CENTER COVER.

2. ENLARGE THE HOLE IN THE SMALLER TERMINAL ON BRAIDED GROUND STRAP (P/N 12091511) TO AN INSIDE DIAMETER OF 5/16 USING A DRILL BIT, FILE, GRINDING TOOL, ETC.

3. USING SCREW (P/N 11508128), SERRATED WASHER (P/N 11501869) AND NUT (P/N 3530297) ATTACH THE ENLARGED TERMINAL TO THE HOLE IN THE WIPER MOTOR BRACKET AS SHOWN IN FIGURE 1. TIGHTEN TO 5 N.M (44 LB IN).

4. ROUTE THE NEW BRAIDED GROUND STRAP AS SHOWN IN FIGURE 1.

5. USING SCREW (P/N 11509371) ATTACH THE OTHER END OF THE BRAIDED GROUND STRAP TO THE EXISTING HOLE IN THE RIGHT FRONT INNER FENDER AS SHOWN IN FIGURE 1. TIGHTEN TO 5 N.M (44 LB IN).

IMPORTANT:

DO NOT ATTACH THE NEW BRAIDED GROUND STRAP TO THE EXISTING GROUND WIRE LOCATION THAT IS JUST REARWARD OF THE HOLE TO BE USED. SEE FIGURE 1.

6. REINSTALL THE WIPER MODULE ASSEMBLY PLASTIC COVER AND FUSE RELAY CENTER COVER.

BRAIDED GROUND STRAP NUMBER 2 (HOOD TO RIGHT FRONT FENDER)

1. ENLARGE THE HOLE IN THE SMALLER TERMINAL ON BRAIDED GROUND STRAP (P/N 12091511) TO AN INSIDE DIAMETER OF 5/16 USING A DRILL BIT, FILE, GRINDING TOOL, ETC.

2. REMOVE THE REARWARD BOLT THAT ATTACHES THE RIGHT SIDE HINGE TO THE HOOD ASSEMBLY. SEE FIGURE 2.

3. INSERT THE BOLT THROUGH THE ENLARGED RING TERMINAL AND THEN THROUGH SERRATED WASHER (P/N 11501869).

4. REINSTALL THE BOLT WITH TERMINAL AND WASHER IN THE HOOD HINGE. POSITION RING TERMINAL AS SHOWN IN FIGURE 2. TIGHTEN TO 25 N.M (18 LB FT).

5. REMOVE THE FORWARD HINGE TO RIGHT FRONT FENDER BOLT. SEE FIGURE 2.

6. INSERT THE BOLT THROUGH THE OTHER RING TERMINAL AND REINSTALL IN FENDER. POSITION RING TERMINAL AND ROUTE BRAIDED GROUND STRAP AS SHOWN IN FIGURE 2. TIGHTEN TO 11 N.M (97 LB IN).

7. VERIFY HOOD CLOSES WITHOUT BRAIDED GROUND STRAP INTERFERENCE.

8. APPLY TOUCH-UP PAINT AS NECESSARY TO HOOD HINGE AND FENDER BOLTS.

BRAIDED GROUND STRAP NUMBER 3 (RADIATOR SUPPORT TO ENGINE BRACKET)

1. REMOVE THE BOLT FROM THE FRONT ENGINE MOUNT BRACKET ON THE RADIATOR SUPPORT AS SHOWN IN FIGURE 3.

2. INSERT THE BOLT THROUGH THE "LARGER" RING TERMINAL ON BRAIDED GROUND STRAP (P/N 6287160) AND THEN THROUGH SERRATED WASHER (P/N 11501869).

3. REINSTALL THE BOLT WITH TERMINAL AND WASHER IN THE BRACKET.

4. POSITION THE RING TERMINAL AS SHOWN IN FIGURE 3. TIGHTEN TO 28 N.M (21 LB FT).

5. REMOVE WIRING HARNESS RETAINING CLIP BOLT FROM RIGHT ENGINE BRACKET AS SHOWN IN FIGURE 3.

6. INSERT THE BOLT THROUGH THE OTHER RING TERMINAL AND REINSTALL IN BRACKET.

7. POSITION RING TERMINAL AND ROUTE BRAIDED GROUND STRAP AS SHOWN IN FIGURE 3. TIGHTEN TO 12 N.M (9 LB FT).

8. RECONNECT NEGATIVE BATTERY CABLE.

9. RESET RADIO STATION PRE-SETS AND CLOCK.

10. CLOSE HOOD AND VERIFY RADIO INTERFERENCE HAS BEEN CORRECTED.

PARTS INFORMATION:

QUANTITY NEEDED PACKAGED P/N DESCRIPTION PER VEHICLE QUANTITY === =========== ================ ========

12091511 STRAP 2 1

6287160 STRAP 1 1

11509371 SCREW 1 5

11508128 SCREW 1 10

11501869 SERRATED WASHER 3 1

3530297 NUT 1 10

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION NUMBER DESCRIPTION LABOR TIME =============== =========== ==========

N6582 RADIO NOISE SUPPRESSION 0.4 HR GROUND STRAPS

IMPORTANT:

LABOR TIME IS FOR INSTALLING ALL THREE GROUND STRAPS.

FIGURES: 3

ATTACHMENTS: 00

FIGURE 1

LEGEND

1. HOLE LOCATION IN FENDER FOR ATTACHING BRAIDED GROUND STRAP WITH SCREW (P/N 11509371) 2. EXISTING GROUND LOCATION IN RIGHT FRONT FENDER (NOT TO BE USED) 3. BRAIDED GROUND STRAP (P/N 12091511) ROUTING LOCATION 4. WIPER MOTOR MOUNTING BRACKET 5. HOLE IN BRACKET FOR ATTACHING BRAIDED GROUND STRAP 6. SCREW (P/N 11508128) 7. BRAIDED GROUND STRAP RING TERMINAL 8. SERRATED WASHER (P/N 11501869) 9. NUT (P/N 3530297)

FIGURE 2

LEGEND

1. HOOD 2. RIGHT HOOD HINGE 3. REARWARD HINGE TO HOOD BOLT 4. FORWARD HINGE TO RIGHT FRONT FENDER BOLT 5. BRAIDED GROUND STRAP (P/N 12091511)

FIGURE 3

LEGEND

1. RIGHT FRONT ENGINE MOUNT BRACKET BOLT ON RADIATOR SUPPORT 2. BRAIDED GROUND STRAP (P/N 6287160) 3. WIRING HARNESS RETAINING CLIP BOLT ON RIGHT ENGINE BRACKET

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.

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