ABS LIGHT ILLUMINATED, NO BRAKE ON, NO CODES OR DATA

REVISION: 03/04/96

THIS BULLETIN IS BEING REVISED TO INFORM "GM OF CANADA" AND "NAES" DEALERS THAT THEY ARE NOT AUTHORIZED TO UTILIZE THIS SERVICE BULLETIN. ----------------------------------------------------------------------

SUBJECT:ABS BRAKE LIGHT ILLUMINATED, NO RED BRAKE LIGHT ON AND NO CODES OR SERIAL DATA RETRIEVED FROM THE TECH-1 OR CAMS (REPAIR POWER OR GROUND AT THE 10 PEN CONNECTOR OR REPLACE BPMV MODULE "CAP" AND RELOCATE G124 GROUND CONNECTION)

MODELS: 1993-94 CHEVROLET AND GMC TRUCK G VANS WITH YF7 ONLY (CONVERSION VANS)

********************************************************************** IMPORTANT: "GM OF CANADA" DEALERS AND "NAES" DEALERS ARE NOT AUTHORIZED TO UTILIZE THIS SERVICE BULLETIN. **********************************************************************

CONDITION:

SOME OWNERS HAVE COMMENTED THAT THE YELLOW ABS LIGHT STAYS ILLUMINATED AT ALL TIMES.

CAUSE:

THERE ARE 3 CONDITIONS WHICH MAY CONTRIBUTE TO THE ABOVE CONDITION. THEY ARE:

1.INSUFFICIENT SUPPLY OF POWER OR GROUND ON THE 10 PIN CONNECTOR GOING INTO THE BPMV. POWER IS RECEIVED THROUGH TERMINAL A OF THE 10 PIN CONNECTOR WHEN THE IGNITION SWITCH IS TURNED TO THE ON POSITION. GROUND IS RECEIVED ON THE 10 PIN CONNECTOR THROUGH TERMINAL J AT ALL TIMES. ANY INTERMITTENT OR CHANGE IN RESISTANCE ON EITHER OF THESE WIRES WILL CAUSE THE ABS MODULE "CAP" (LOCATED IN THE BPMV) TO MALFUNCTION. TECHNICIANS SHOULD CAREFULLY CHECK FOR CHANGING OR HIGH RESISTANCE THROUGH TERMINAL A OR J.

2.A CAPACITOR C35 MOUNTED TO THE PRINTED CIRCUIT BOARD OF THE BPMV MAY BECOME A DIRECT CURRENT PATH TO GROUND, CAUSING DAMAGE TO THE COMPONENT AND THE PRINTED CIRCUIT BOARD. IF THIS OCCURS, THE BPMV MODULE "CAP" WILL BECOME DISABLED.

3.THE BPMV AND PCM, AND BODY GROUND SHARE THE SAME LOCATION ON THE BACK OF THE RIGHT HAND CYLINDER HEAD. THE BODY GROUND STRAP "G124" SHOULD BE MOVED AWAY FROM THIS LOCATION TO PREVENT FUTURE MODULE PROBLEMS.

CORRECTION:

REPLACE THE BPMV CONTROL MODULE ASSEMBLY "CAP" AND RELOCATE THE BODY GROUND G124 TO A NEW LOCATION.

IT WILL BE NECESSARY TO PROPERLY DIAGNOSE THIS CONDITION BY FOLLOWING THE PROCEDURES LOCATED IN THE DIAGNOSTICS AND SERVICE PROCEDURES PROVIDED BELOW. ONCE YOU HAVE ACHIEVED THE PROPER DEFINITION OF THE ABOVE CONDITION, IT IS MANDATORY THAT YOU CONTACT K-TAC 1(800) 546-4227 FOR FURTHER INFORMATION.

DIAGNOSTICS PROCEDURE:

1.CONNECT TECH-1 OR CAMS TO THE DLC. IF A DTC CODE IS CAPTURED, REFER TO THE SERVICE MANUAL FOR PROPER REPAIRS. IF NO DTC CODES OR SERIAL DATA IS NOT CAPTURED, CONTINUE DIAGNOSTICS.

2.REMOVE TECH-1 OR CAMS. USING A DVM (DIGITAL VOLT METER) OR EQUIVALENT, "NOT A LIGHT METER", MEASURE VOLTAGE AT THE DLC DIAGNOSTICS CONNECTOR PIN "A" TO PIN "H". IF VOLTAGE REGISTERS BELOW 5 VOLTS, RECORD THIS VOLTAGE ON THE REPAIR ORDER FOR FURTHER REFERENCE.

3.DISCONNECT THE 10 PIN CONNECTOR FROM THE BPMV. USING A DVM (DIGITAL VOLT METER) OR EQUIVALENT, "NOT A LIGHT METER", MEASURE VOLTAGE AT PIN "A" TO PIN "J". THIS PROCEDURE IS TO IDENTIFY THE IGNITION FEED SIGNAL. RECORD VOLTAGE ON THE REPAIR ORDER FOR FURTHER REFERENCE.

4.IT WILL BE NECESSARY TO PROPERLY DIAGNOSE THIS CONDITION BY FOLLOWING THE PROCEDURES LOCATED IN THE DIAGNOSTICS AND SERVICE SECTION PROVIDED. ONCE YOU HAVE ACHIEVED THE PROPER DEFINITION OF THE ABOVE CONDITION, IT IS MANDATORY THAT YOU CONTACT K-TAC AT 1-800-546-4227 FOR FURTHER INFORMATION.

SERVICE PROCEDURE:

THE SERVICE PROCEDURE WILL BE INCLUDED IN THE PARTS KIT.

FLINT ASSEMBLY VIN BREAKPOINTS: (FROM SOP 1993 TO THE FOLLOWING VIN BREAKPOINTS 1994)

CHEVROLET: RF120591 GMC: RF507903

SERVICE PARTS INFORMATION

THE BPMV MODULE "CAP" MUST BE ORDERED THROUGH K-TAC. THE KIT ASSEMBLY P/N IS 12891300.

ALL REPLACED BPMV MODULES "CAPS" MUST BE RETURNED TO KELSEY-HAYES FOR ANALYSIS.

WARRANTY INFORMATION

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OP DESCRIPTION LABOR TIME T7781 G124 GROUND RELOCATION 0.5 HRS. ADD ELECTRICAL DIAGNOSIS 0.3 HRS. ADD BPMV MODULE "CAP" 0.6 HRS.

IMPORTANT: LABOR OPERATION IS CODED TO BASE VEHICLE COVERAGE IN THE WARRANTY SYSTEM.

FIGURES: 3

CAPTIONS: FIGURE 1 - REMOVE AND RELOCATE G124 BODY GROUND. FIGURE 2 - HARNESS, 8 AND 10 PIN CONNECTORS. FIGURE 3 - "CAP" TORQUE SEQUENCE.

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.

COPYRIGHT 1994 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.

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THE FOLLOWING IS THE SERVICE PROCEDURE TO BE INCLUDED IN THE PARTS KIT FOR BULLETIN 465001

T H I S S H O U L D N O T B E P U B L I S H E D W I T H B U L L E T I N *******************************************************************

INSTALLATION PROCEDURES BODY GROUND (G124) BPMV MODULE "CAP"

REMOVE AND RELOCATE G124 BODY GROUND (FIGURE 1). THIS PROCEDURE SHOULD BE PERFORMED WITH THE NEGATIVE BATTERY CABLE DISCONNECTED.

SERVICE REMOVAL PROCEDURE: (BPMV CONTROL MODULE "CAP")

IMPORTANT: THE ELECTRONIC COMPONENTS INSIDE THE BPMV CONTROL MODULE "CAP" ARE STATIC SENSITIVE. KEEP ALL TOOLS AND HANDS OUT OF THE "CAP". CONTACT WITH ANY INTERNAL COMPONENT MAY RESULT IN BPMV CONTROL MODULE FAILURE.

1. WITH THE ENGINE OFF, DISCONNECT THE NEGATIVE BATTERY CABLE.

2. RAISE THE VEHICLE AND SUPPORT WITH SUITABLE SAFETY STANDS.

3. REMOVE SPLASH SHIELD MOUNTING BOLTS.

4. REMOVE BPMV MOUNTING BRACKET BOLTS FROM VEHICLE (FIGURE 2).

NOTE: DO NOT DISCONNECT THE HYDRAULIC BRAKE LINES.

5. GENTLY PULL DOWN THE BPMV FROM THE REAR OF THE VEHICLE WHILE ALLOWING THE FRONT PORTION OF THE BRACKET TO REST AGAINST THE VEHICLE BODY CROSS MEMBER. DO NOT LET THE ENTIRE BPMV HANG. THIS MAY BEND OR DAMAGE THE HYDRAULIC BRAKE LINES.

6. DISCONNECT THE 8 PIN AND 10 PIN HARNESS CONNECTOR (FIGURE 2).

7. USING A T-25 TORX TOOL WITH AN INSET CENTER (HOLLOW POINT), LOOSEN EACH BOLT 1/2 TURN. A T-25 TORX HAS BEEN SUPPLIED IN THE SERVICE KIT (FIGURE 3).

NOTE: DO NOT USE POWER TOOLS FOR REMOVAL OR REPLACEMENT. BOLT HEADS STRIP EASILY.

NOTE: FOLLOW THE TORQUE/LOOSENING PATTERN IN FIGURE 3 WHEN LOOSENING THE "CAP".

8. REMOVE THE "CAP" BY GRASPING THE HOUSING, TOP AND BOTTOM OF THE "CAP". PULL EVENLY AWAY FROM THE BPMV.

NOTE: THE "CAP" IS CONNECTED INTERNALLY TO THE HYDRAULIC SIDE BY A 17 PIN CONNECTOR. THE "CAP" MUST BE REMOVED EVENLY TO PREVENT DAMAGE TO THIS CONNECTOR.

NOTE: DO NOT INSERT TOOLS BETWEEN THE "CAP" AND HYDRAULIC UNIT TO AID IN REMOVAL. DAMAGE TO THE "CAP" OR HYDRAULIC INTERFACE MAY OCCUR.

9. REMOVE RUBBER DIAPHRAGM BY GRASPING FIRMLY, CLOSE TO THE 17 PIN CONNECTOR, PULLING EVENLY AWAY FROM THE BPMV.

SERVICE INSTALLATION PROCEDURE:

IMPORTANT: THE BPMV HYDRAULIC PORTION OF THE BPMV MUST BE FREE OF DIRT AND CONTAMINANTS. FOREIGN MATERIALS ARE HARMFUL TO THE INTERNAL COMPONENTS OF THE HYDRAULIC SYSTEM. PRIOR TO INSTALLATION PROCEDURES, INSPECT THE HYDRAULIC UNIT, DIAPHRAGM, AND "CAP" FOR FOREIGN MATERIAL. CLEAN COMPONENTS IF APPLICABLE.

1. INSTALL NEW RUBBER DIAPHRAGM (PROVIDED) BY PUSHING OVER THE 17 PIN CONNECTOR EVENLY. DO NOT TOUCH THE 17 PINS WITH HANDS. ENSURE THAT ALL ALIGNMENT PINS ALONG THE PERIMETER OF THE HYDRAULIC INTERFACE ARE FIRMLY IN PLACE, AND LINE UP EVENLY.

2. INSTALL NEW "CAP" BY HOLDING FIRMLY IN BOTH HANDS WHILE MAKING CONNECTION TO THE 17 PIN CONNECTOR EVENLY. THE CONNECTOR PINS WILL ENGAGE FIRST. PUSH THE "CAP" FIRMLY ONTO THE HYDRAULIC UNIT. VERIFY ALIGNMENT OF THE "CAP" ON THE HYDRAULIC UNIT AFTER INSTALLATION BY VISUALLY NOTING A FLUSH CONTACT ON THE "CAP" CASTING ALONG THE COMPLETE PERIMETER OF THE HYDRAULIC UNIT.

NOTE: EVEN PRESSURE MUST BE APPLIED TO THE "CAP" WHILE INSTALLING TO PREVENT 17 PIN CONNECTOR DAMAGE.

3. INSTALL NEW BOLTS (PROVIDED) BY HAND. TORQUE EACH BOLT TO .56-1.13 N.M (5-10 LBS. IN.) USING THE SAME REMOVAL PATTERN (FIGURE 3).

NOTE: DO NOT USE POWER TOOLS. BOLT HEADS STRIP EASILY AND EXACT TORQUE MUST BE MAINTAINED. IMPROPER TORQUE SEQUENCING MAY DAMAGE THE HYDRAULIC INTERFACE OR THE INTERNAL PCB BOARD.

4. TORQUE EACH BOLT FOLLOWING SEQUENCE PATTERN TO 5.6-6.7 N.M (50-60 LBS. IN.). USE THE FOLLOWING SEQUENCE: 1.1 N.M (10 LBS. IN.), 3.4 N.M (30 LBS. IN.), 5.6-6.7 N.M (50-60 LBS. IN.).

5. INSTALL THE 8 PIN AND 10 PIN CONNECTORS. VERIFY PIN ALIGNMENT PRIOR TO CONNECTION (FIGURE 2).

6. INSTALL BPMV/MOUNTING BRACKET BACK INTO PLACE ON THE VEHICLE. INSTALL MOUNTING BOLTS AND TORQUE TO 75 N.M (55 LBS. FT.) (FIGURE 2).

7. INSTALL SPLASH SHIELD. TORQUE BOLTS TO 16 N.M (12 LBS. FT.).

8. REMOVE SAFETY STANDS. LOWER VEHICLE.

9. INSTALL NEGATIVE BATTERY CABLE.

VERIFY PROPER ABS LIGHT FUNCTION. TURN IGNITION ON WITHOUT STARTING THE ENGINE. THE LIGHT SHOULD COME ON AND REMAIN ON APPROXIMATELY 2 SECONDS, THEN TURN OFF. IF THE LIGHT STAY ON FOR MORE THAN 10 SECONDS, TURN ENGINE OFF AND VERIFY CONNECTOR PIN CONNECTIONS.