SER. MANUAL UPDATE-CODE C553 PREVENT UNNECESSARY PARTS REPL

SUBJECT: SERVICE MANUAL UPDATE REVISIONS FOR CODE C553

MODELS/YEARS: 1989 TORONADO

The diagnostic procedure for code C553 (page 8D2-77 in the service manual) is being revised to eliminate unnecessary CRT controller replacements. See the illustration on the back of this bulletin.

IMPORTANT: The color CRT monitor and control module is referred to in the Owner's Manual as "Visual Information Center" (VIC) and by the GMSPO parts system as "Driver Information Display" (DID). The vehicle on-board diagnostic system refers to it as CRT. Obtain exchange parts for warranty service by calling one of the 26 AC-Delco shops listed in Oldsmobile Management Bulletin 91-I-14. The exchange procedure is described in Management Bulletin 90-I-12.

If code C553 is set and the CRT is functioning properly, do not attempt any repair. A fault internal to the CRT controller causes a false code C553 to set that cannot be cleared. The CRT operates normally with this fault.

If there is a complaint of loss of CRT display, follow the procedure on 8D2-77 to diagnose.

The schematic for code C553 (page 8D2-76) has been revised to correct an incorrect pin number and wire color. Refer to the illustration on the back of this bulletin for the correct schematic.

CODE C553 CRT KEEP ALIVE MEMORY ERROR

CIRCUIT DESCRIPTION Code C553 does not necessarily indicate a fault but is a normal occurrence anytime the battery power to the CRTC has been interrupted.

This code could set if the system voltage drops below 8 volts at CRTC terminal 'A7'. Possible causes for this

are:

o Faulty charging system. o Faulty starter system. o Extreme cold weather. o Jump starting vehicle.

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.