DIAGNOSTIC PROCEDURES REVISE CODE CLEARING STEPS

USE OF AN IMPROPER CODE CLEARING PROCEDURE FOLLOWING REPAIRS ON 1980 DEFI OR 1981-1983 DFI-EQUIPPED VEHICLES MAY, IN SOME CASES, RESULT IN A RECURRENCE OF THE CODE AND ILLUMINATION OF A SERVICE TELL-TALE INDICATOR UPON EXISTING DIAGNOSTICS. TO PREVENT MISDIAGNOSIS, THE CORRECT CODE CLEARING PROCEDURE, LISTED BELOW AND DESCRIBED ON PAGE 8D1-3 OF THE 1982 AND 1983 SERVICE INFORMATION MANUALS, MUST BE FOLLOWED EXACTLY!!!! THE CODE CLEARING PROCEDURE LISTED IN THE 1980 SERVICE INFORMATION MANUALS AND THE1981 DIGITAL FUEL INJECTION AND COMPUTER COMMAND CONTROL DIAGNOSTIC MANUAL SUPPLEMENT ARE INCORRECT AND ARE TO BE SUPERSEDED BY THAT LISTED BELOW; PLEASE UPDATE YOUR MANUALS. THE PROPER CODE CLEARING PROCEDURE IS AS FOLLOWS: 1. ENTER THE DIAGNOSTIC MODE BY DEPRESSING THE 'OFF' AND 'WARMER' BUTTONS ON THE ECC PANEL SIMULTANEOUSLY UNTIL '....' APPEARS. 2. DEPRESS THE 'OFF' AND 'HI' BUTTONS SIMULTANEOUSLY. HOLD UNTIL '.0.0' OR '00' APPEARS. 3. WHEN THE ECC CONTROL PANEL DISPLAYS '7.0' OR '70', TURN THE IGNITION OFF FOR AT LEAST 10 SECONDS BEFORE RE- ENTERING THE DIAGNOSTIC MODE. UNNECESSARY ECM REPLACEMENTS MAY RESULT IF THE ABOVE PROCEDURE IS NOT FOLLOWED EXACTLY!!! FOR EXAMPLE, IF A CODE 18 IS CLEARED BY THE IGNITION IS NOT TURNED OFF FOR AT LEAST 10 SECONDS, THE ECM WILL NOT POWER DOWN AND MAY NOT HAVE SEEN A CRANK SIGNAL DURING THE CURRENT IGNITION CYCLE, RESULTING IN A RESETTING OF CODE 18. THEREFORE, A TECHNICIAN MAY BE MISLED INTO BELIEVING THAT FURTHER REPAIRS ARE REQUIRED. DISCONNECTING THE ECM DURING THE REPLACEMENT PROCESS WILL CLEAR CODES AND MAY LEAD TO AN INCORRECT CONCLUSION THAT AN ECM REPLACEMENT, WHICH WAS IN FACT UNNECESSARY, CORRECTED THE CONDITION.

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.