PDF associated: /PT 77-0009.pdf

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JDB0280 PT 77 0009 Rev 1 10 Step Driveability Test All Electronic Computer Controlled Vehicles Drivability problems continue after ECM replacement 80 of drivability problems are engine related Before condemning the replacement ECM check for computer codes and correct any indicated problems then perform this 10 Step Driveability Check list 1 Check vehicle and all ECM grounds using voltage drop test method see ProTech PT 77 0008 2 No load battery voltage should be 12 46 to 12 66 volts 3 Cranking voltage must be 9 5 volts or higher 4 Charging voltage from 13 2 to 14 7 and charge current within 10 amps of related alternator output 5 Check distributor primary and secondary voltage at idle and 2500 RPM 6 Check base and advance timing at idle and 2500 RPM 7 Vacuum level and volume at idle and 2500 RPM 8 Fuel pressure and volume at idle and under load 9 O2 sensor switching at idle and 2500 RPM 10 Check manufacturer s Technical Service Bulletins for revised ECM updated PROM GM or related components Application Problem Cause Solution Check List