For 1990-2009 cars

# SMU - SEC. 5E - REV. DIAG. PROCEDURES FOR ABS/TCS DTC 74

#### SUBJECT: SERVICE MANUAL UPDATE - SECTION 5E - REVISED DIAGNOSTIC PROCEDURES FOR ABS/TCS DIAGNOSTIC TROUBLE CODE (DTC) 74

#### MODELS: 1992-93 BUICK PARK AVENUE/PARK AVENUE ULTRA 1992-93 BUICK LESABRE 1992-93 OLDSMOBILE NINETY EIGHT 1992-93 OLDSMOBILE EIGHTY EIGHT 1992-93 PONTIAC BONNEVILLE

THIS BULLETIN REVISES DIAGNOSTIC PROCEDURES FOR ABS/TCS DIAGNOSTIC TROUBLE CODE (DTC) 74 ON THE ABOVE LISTED VEHICLES EQUIPPED WITH TCS SYSTEMS.

"TRACTION OFF" INDICATOR LAMP IS ON AND THE TRACTION CONTROL SYSTEM DISABLED DUE TO THE PRESENCE OF ABS/TCS DIAGNOSTIC TROUBLE CODE (DTC) 74.

ABS/TCS DTC 74 CAN SET DUE TO THE FOLLOWING CONDITIONS:

1. FAULTY OR MISADJUSTED BRAKE SWITCH.

2. SHORT TO GROUND IN BATTERY CIRCUIT TO BRAKE SWITCH.

3. FAULTY PRESSURE MODULATOR VALVE (PMV) PRESSURE SWITCH.

4. FAULTY PMV.

5. EBTCM DETECTS SHORT TO GROUND OR VOLTAGE AT TERMINALS 5, 8, 13, 26 OR 32.

6. EBTCM DETECTS AN OPEN IN THE PRESSURE SWITCH INPUT, BRAKES APPLIED INPUT OR RETURN INPUT CIRCUITS.

7. POOR TERMINAL CONTACT (PMV, EBTCM CONNECTORS).

8. POOR GROUND OR LOSS OF GROUND TO EBTCM.

THE ATTACHED DTC 74 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.

FIGURES: 3

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.