EXPERTEC TSB (476513)

Publication date: 1994-06-06
Reference number: 476513

EXPERTEC TSB

TECHNICAL SERVICE BULLETIN

Reference Number(s): 476513, Date of Issue: 06/06/94

INTERMITTENT MISS/SURGE/LACK - OF POWER (REPAIR WIRING)

Model(s): 1993-94 Cadillac Eldorado, Seville, & Concours

Bulletin No.: Cadillac 476513

Date: 06/06/1994

BULLETIN ILLUSTRATION LIST

Fig 1: Graphic

VEHICLE INFORMATION

1993-94 CADILLAC ELDORADO, SEVILLE, AND CONCOURS WITH 4.6L NORTHSTAR ENGINE (VINS Y, 9 - RPOS LD8, L37)

* THIS BULLETIN CANCELS AND SUPERSEDES BULLETIN NUMBER 476401 TO *

* CORRECT THE CATEGORY IDENTIFIER/GROUP REFERENCE. PLEASE DISCARD *

* BULLETIN 476401 (GROUP REFERENCE 6 - ENGINE). *

CONDITION

SOME OWNERS MAY EXPERIENCE AN INTERMITTENT MISS, SURGE OR LACK OF POWER ON A MODERATE TO HARD ACCELERATION OR AT STEADY SPEEDS WITH NO PCM DTC CODES SET.

CAUSE

THIS CONDITION MAY BE CAUSED BY AN INTERMITTENT SHORT TO GROUND ON THE PARK/NEUTRAL INPUT (PI79) TO THE PCM. THE PARK/NEUTRAL INPUT (PI79), IS A NORMALLY "HI" INPUT TO THE PCM WHEN THE GEAR SELECTOR IS IN ANY OF THE DRIVE POSITIONS AND "LO" IN PARK OR NEUTRAL. IF (PI79) GOES "LO" WHILE DRIVING, THE PCM WILL ENABLE THE TORQUE MANAGEMENT MODE. DURING THE TORQUE MANAGEMENT MODE, THE PCM WILL REDUCE ENGINE POWER BY RETARDING THE TIMING AND SHUTTING OFF 4 INJECTORS. THE PARK/NEUTRAL INPUT, CIRCUIT 434 (AN ORANGE/BLACK WIRE), MAY BE SHORTING TO THE TRANSAXLE CASE NEAR THE PRNDL SWITCH CONNECTOR (SEE Fig. 1).

CORRECTION

TO REPAIR THIS CONDITION, USE THE WIRING REPAIR PROCEDURES IN THE SERVICE MANUAL, SECTION 8A-5. AFTER THE CIRCUIT HAS BEEN REPAIRED, THE HARNESS SHOULD BE REPOSITIONED USING PLASTIC TIE STRAPS TO PREVENT CONTACT WITH THE TRANSAXLE CASE CAUSED BY ENGINE MOVEMENT DURING ACCELERATION.

WARRANTY INFORMATION

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION NUMBER: J6383

(Fig 1 )

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.