OIL LIFE MONITOR STAYS ON (NEW SERVICE PART RELEASED)

SUBJECT: OIL LIFE MONITOR (NEW SERVICE PART)

MODELS AFFECTED: 1991 PARK AVENUE/PARK AVENUE ULTRA

CONDITION:

----------- Some 1991 Park Avenue/Park Avenue Ultras with option "UB3" Instrumentation (includes Engine Oil Life), may exhibit a condition where the customer complains that the "Change Oil Soon" telltale is illuminated whenever the ignition is on. In some cases it may stay on only for one ignition cycle and go out the next time the key is turned on.

CAUSE:

------ The cause of this condition may be one of three problems:

1. With the ignition on, engine off and the module has determined that it is time for the oil to be changed, a false code 27 can be set in the module and the "Change Oil Soon" telltale will stay illuminated. This code will clear (show up as history only) when the engine is started and will clear when the module is reset.

2. With the ignition on, engine running or not, the module goes into a data scramble which causes a code 14 to be stored and the "Change Oil Soon" telltale will stay illuminated. This code will clear when the module is reset but the condition could reoccur.

3. With the ignition on, engine running or not, the module can falsely set a code 13 indicating loss of data from the ECM. The "Change Oil Soon" telltale will stay illuminated and this code will clear when the module is reset. This condition is intermittent and may correct itself, turning the "Change Oil Soon" telltale off during an ignition cycle causing intermittent warning light operation.

CORRECTION:

------------ To correct the above conditions, a new Engine Oil Life Module has been released for service.

PARTS INFORMATION

The new module, part number 25606364, is currently available from GMSPO.

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.