SMU - SEC. 5E- REVISED DIAG. PROCEDURES FOR ABS OR ABS/TCS

SUBJECT: SERVICE MANUAL UPDATE - SECTION 5E - REVISED DIAGNOSTIC PROCEDURES FOR ABS OR ABS/TCS DIAGNOSTIC TROUBLE CODE 45

MODELS: 1991-94 BUICK PARK AVENUE/PARK AVENUE ULTRA 1991-93 CADILLAC DEVILLE, FLEETWOOD AND SIXTY SPECIAL 1991-94 OLDSMOBILE NINETY EIGHT

1991-94 BUICK LESABRE 1991-94 OLDSMOBILE EIGHTY-EIGHT 1991-94 PONTIAC BONNEVILLE

THIS BULLETIN REVISES DIAGNOSTIC PROCEDURES FOR ABS OR, IF EQUIPPED, ABS/TCS DIAGNOSTIC TROUBLE CODE (DTC) 45 ON THE ABOVE LISTED VEHICLES EQUIPPED WITH ABS OR ABS/TCS SYSTEMS.

"ABS" AND, IF EQUIPPED, "TRACTION OFF" INDICATOR LAMPS ARE ON AND BOTH SYSTEMS DISABLED DUE TO THE PRESENCE OF ABS OR ABS/TCS DIAGNOSTIC TROUBLE CODE (DTC) 45.

ABS OR ABS/TCS DTC 45 CAN SET DUE TO THE FOLLOWING CONDITIONS:

1. OPEN OR SHORT TO GROUND IN THE LEFT FRONT INLET VALVE CIRCUIT. 2. NO BATTERY VOLTAGE DETECTED AT THE PRESSURE MODULATOR VALVE (PMV) WHEN THE IGNITION SWITCH IS IN THE "RUN" POSITION. 3. NO BATTERY VOLTAGE DETECTED AT THE EBCM/EBTCM TERMINALS 33, 35 (TRACTION CONTROL ONLY), 3, 53 OR 20. 4. MAIN RELAY FAILS OPEN. 5. OPEN IN MAIN RELAY CONTROL CIRCUIT. 6. HIGH RESISTANCE IN ANY PMV INLET/OUTLET VALVE CIRCUIT. 7. IF EQUIPPED WITH TRACTION CONTROL, HIGH RESISTANCE IN ANY ISOLATION VALVE CIRCUIT. 8. POOR TERMINAL CONTACT (PMV, EBCM/EBTCM OR MAIN RELAY CONNECTORS). 9. POOR GROUND OR LOSS OF GROUND TO EBCM/EBTCM.

IN ADDITION, DTC 45 MAY ALSO SET INTERMITTENTLY DUE TO LOW SYSTEM VOLTAGE (EXTENDED CRANKING, LOW BATTERY BUT VEHICLE EVENTUALLY STARTS, ETC.).

THE ATTACHED DTC 45 DIAGNOSTIC CHARTS SHOULD BE UTILIZED AFTER ALL PROPER SYSTEM CHECKS AND VISUAL INSPECTIONS HAVE TAKEN PLACE PER THE APPLICABLE SERVICE MANUAL DIAGNOSTIC PROCESS. THE CHARTS PROVIDED MUST BE USED IN CONJUNCTION WITH THE APPLICABLE SERVICE MANUAL SECTION 8A-44 OR BUICK ELECTRICAL SYSTEMS MANUAL (ABS SECTION) SCHEMATICS.

THE VEHICLE SHOULD BE IN "PARK" AND ALLOWED TO IDLE WITH THE HOOD DOWN FOR AT LEAST TWENTY MINUTES BEFORE PROCEEDING WITH THE DIAGNOSTIC CHARTS.

FIGURES: 5

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 1993 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.