For 1990-2009 cars

# DISCHARGED BATTERY OR NO CRANK ECM NOT POWERING DOWN

A BATTERY DRAIN MAY BE EXPERIENCED ON SOME 1981-1985 DFI EQUIPPED VEHICLES AS A RESULT OF THE ELECTRONIC CONTROL MODULE (ECM) NOT POWERING DOWN WITH THE IGNITION SWITCH OFF. THIS CAN BE DIAGNOSED AS FOLLOWS: 1. TURN IGNITION ON, ENTER DIAGNOSTICS. 2. NOTE ECM PARAMETER .0.9 "IGNITION CYCLES." 3. TURN IGNITION OFF FOR AT LEAST 10 SECONDS TO ALLOW ECM TO POWER DOWN. 4. TURN IGNITION ON, RE-ENTER DIAGNOSTICS AND NOTE ECM PARAMETER .0.9. THE IGNITION CYCLE COUNTER SHOULD INCREMENT BY ONE. IF THIS DOES NOT OCCUR AND NO "HARD" TROUBLE CODES ARE PRESENT, THE ECM IS UNABLE TO POWER DOWN AND MUST BE REPLACED. THE FAILURE OF THE ECM TO POWER DOWN CAN ALSO BE DETERMINED BY OBSERVING THE FIVE-VOLT REFERENCE AT THE TPS TEST POINT WITH THE IGNITION OFF. IF THE FIVE-VOLT REFERENCE REMAINS AT 5 VOLTS AFTER THE IGNITION HAS BEEN OFF FOR 10 SECONDS, THE ECM SHOULD BE REPLACED. SHOULD THE IGNITION CYCLE COUNTER INCREASE BY ONE, THE BATTERY DRAIN MUST BE DIAGNOSED USING THE PROCEDURE IN THE "ENGINE ELECTRICAL" SECTION OF THE APPROPRIATE SERVICE INFORMATION MANUAL.

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.