DME 7.8 DME 7.80 · This may be important in the case of output to a scan tool, as there

DME 7.8 DME 7.80 This may be important in the case of output to a scan tool, as there may be only one freeze frame that can be displayed, although sev- eral faults are stored (misfires or fuel supply faults override the freeze frames of other faults). Freeze frames can, for example, be examined in the "extended fault memory" of the 9588 Porsche System Tester ll. The control module must be able to output the following freeze frame data to a standard diagnostic unit (scan tool): ♦Fault codes causing this freeze frame to be stored ♦Engine load ♦Engine speed ♦Coolant temperature ♦Oxygen control status (open or closed loop) ♦Mixture adaptation values ♦Fuel pressure (if available - not the case for DME 7.8) ♦Intake pipe pressure (if available - in the case of DME 7.8 for turbo vehicles only) ♦Vehicle speed In the case of DME 7.8, a freeze frame is stored for each initial occurrence of a fault that contains all the actual values referred to above with the exception of fuel pressure. See also the next sec- tion. Further environmental conditions In addition with DME 7.8, for every occurrence of a fault, three fur- ther operating conditions (actual values at time of fault occurrence) as well as operating hours and total mileage since model year 2002 are also stored. There is a memory entry for the first occurrence of the fault (remains stored) and a further entry for each last occur- rence of the fault (updated for each new occurrence). This data can provide reference points to the cause of the fault in difficult diag- noses and can only be viewed in the "extended fault memory" of the 9588 Porsche System Tester II. The list of possible environmental conditions partly covers more than one freeze frame so that impor- tant environmental conditions can also be stored after the first fault occurrence. Fault persistence (confirmation of a suspected fault) When a fault occurs for the first time during a diagnostic routine, it is stored as a suspected fault. At the same time a fault persistence counter is started with a certain value (e.g. 2). In the course of fur- 0-PEIN page 6 2470 INTRODUCTION PEIN2DME78 Printed in Germany – 14, 2003