[Manitcor]

SUBJECT: DIAGNOSTIC TROUBLE CODE P0601 IS SET IN THE POWERTRAIN CONTROL MODULE (PCM) (INSTALL NEW PCM)

MODELS: 1996 BUICK CENTURY, LESABRE, PARK AVENUE, REGAL, RIVIERA, SKYLARK 1996 CHEVROLET BERETTA, CORSICA, CAMARO, LUMINA, MONTE CARLO, LUMINA APV 1996 OLDSMOBILE ACHIEVA, CUTLASS CIERA, CUTLASS SUPREME, 88 ROYALE, LSS, 98 REGENCY, SILHOUETTE 1996 PONTIAC BONNEVILLE SE, SSE, SSEI, FIREBIRD GRAND AM, GRAND PRIX, TRANS SPORT WITH 3800, 3100, 3400, 3.4L TWIN DOHC ENGINE (VINS X, M, E, K, 1--RPOS LQ1, L82, LA1, L36, L67)

CONDITION:
OWNERS MAY COMMENT THAT THE MALFUNCTION INDICATOR LAMP (MIL) IS ILLUMINATED ON THE INSTRUMENT PANEL OF THEIR VEHICLE. IT IS ALSO POSSIBLE THAT THE OWNER MAY HAVE EXPERIENCED A HARD OR NO START CONDITION.

CAUSE:
AN INTERNAL RESONANT FREQUENCY INDUCED BY A SET OF DIODES CAUSES THE PCM TO FAIL THE SELF TEST (CHECKSUM ERROR).

CORRECTION:
THE PCM DIODES WERE CHANGED SO THAT THEY OPERATE WITH A DIFFERENT RESONANT FREQUENCY WHICH ELIMINATES THE CHECKSUM ERROR. PCM'S WHICH HAVE AN EIGHTH DIGIT OF FIVE OR LESS (AS OUTLINED BELOW) WILL HAVE TO BE REPLACED.

PARTS INFORMATION:
GMSPO INVENTORY HAS BEEN PURGED AND RESTOCKED. DEALER PARTS INVENTORY OF POWERTRAIN CONTROL MODULES CAN BE SORTED BY LOOKING AT THE LABEL ON THE CASE OF THE PCM. THERE IS A 16 DIGIT NUMBER UNDER THE BAR CODE. THE 8TH DIGIT IN SHOULD BE A 6 OR GREATER (FIGURE 1). PCM'S BUILT WITH AN 8TH DIGIT OF 6 OR GREATER WILL CONTAIN THE INTERNAL CHANGES WHICH WILL PREVENT A CODE P0601 FROM BEING ERRONEOUSLY SET.
APPLICATION PART NUMBER DESCRIPTION QUANTITY

F L36 16207326 PCM 1
C/H/G/W L36 16231853 PCM 1 L67
A/L/N/W L82 16231853 PCM 1
W LQ1 16231853 PCM 1
U LA1 16231853 PCM 1

PARTS ARE EXPECTED TO BE AVAILABLE ON AUGUST 5, 1996 FROM GMSPO.

Figure 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.

COPYRIGHT 1996. GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.