Auto Service World
Feature   September 1, 2006   by Jim Anderton, Technical Editor

Warming up for On-Board Diagnostics

Do you follow complete procedures when using your scan tool? There's more to it than plug-and-read.

Do you go straight to the scan tool when tracking down drivabilty issues? Many techs do, and most do get to the problem eventually. OEM’s, however, intended their systems to yield the most accurate information after a specific, careful conditioning procedure. Take a look at the following scanning procedure from Ford, which exercises the OBDII monitors and clears Ford’s P1000 inspection/maintenance readiness code. It’s complex, but it helps eliminate “blind alleys” when troubleshooting the tough ones.

To complete a specific monitor for repair verification, follow steps 1 through 4, then continue with the step described by the appropriate monitor found under the “OBDII Monitor Exercised” column. When the ambient air temperature is outside 4.4 to 37.8C (40 to 100 F), or the altitude is above 2,438 meters (8,000 feet), the EVAP monitor will not run. If the P1000 code must be cleared in these conditions, the PCM must detect them once (twice on some applications) before the EVAP monitor can be “bypassed” and the P1000 cleared. The Evap “bypassing” procedure is described in the following drive cycle. The OBDII Drive Cycle will be performed using a scan tool. Consult the instruction manual for each described function. NOTE: A detailed description of a Powertrain Control Module (PCM) Reset is found in this section, refer to the table of contents.

Drive Cycle Recommendations:

1. Most OBDII monitors will complete more readily using a “steady foot” driving style during cruise or acceleration modes. Operating the throttle in a “smooth” fashion will minimize the time required for monitor completion.

2. Fuel tank level should be between 1/2 and 3/4 fill, with 3/4 fill being the most desirable.

3. The Evaporative Monitor can only operate during the first 30 minutes of engine operation. When executing the procedure for this monitor, stay in part throttle mode and drive in a smooth fashion to minimize “fuel slosh.”

Click here for the step by step intstructions.


Strict observance of posted speed limits and attention to driving conditions are mandatory when proceeding through all drive cycles.

Check your repair database for procedures specific to the vehicle you’re working on, and remember, this kind of careful diagnostic takes time, billable time. Don’t forget to make this clear to consumers confused by the apparently high cost of diagnostics and always remind them that procedures like these improve the chances of a “first-fix.” That builds customer satisfaction.

Thanks to Ford Motor Company Ltd.

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