MICROSCAN User Manual - Snap-on

On-Board Diagnostics (OBD) Diagnostic Services Introduction
Repair validation
Use the following procedure to validate a repair.
z To validate the repair:
1. Perform a drive cycle (generic or vehicle specific).
2. Check Service $07 (refer to 4.6.7: ‘Service $07: Emission-related DTCs detected during
Current or Last Completed Drive Cycle (Pending Codes)’ on page 25) and Service $03 (refer
to 4.6.3: ‘Service $03: Emission-related DTCs’ on page 18).
If no DTCs are reported (that relate to the initial failure), it can be assumed that the fault has been
repaired correctly.
4.5.2 MIL Status
Emission related malfunctions set failure specific DTC(s). The MIL (Malfunction Indicator Lamp)
may light up as soon as the first emission related DTC has been stored and confirmed (stored a
second time). Depending on the type of malfunction, it may take multiple drive cycles before the
MIL turns on.
The MIL is located in the instrument panel. The MIL may display a symbol of an engine and should
light up as soon as the ignition is switched on. Three different states are possible when the engine
is running:
1. OFF: no emission limits exceeded.
2. ON: at least one OBD-II/EOBD emission limit exceeded.
3. Blinking: possibility of damage to the catalytic converter.
Figure 4-2 Example of Malfunction Indicator Lamp
NOTE:
i The MIL may also be called the “Check Engine” lamp.
The ECM transmits the status of the Malfunction Indicator including the identification of the ECM
that commanded the MIL to turn on.
NOTE:
i The MIL status indicates “off” during the ignition key on, engine off instrument panel bulb check
unless the MIL has been commanded “on” for a detected malfunction.
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