User Manual
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Professional 909X User Manual
illuminated Malfunction Indicator Lamp (MIL), check monitor status prior to
emissions certification testing, verify repairs, and perform a number of other
services that are emission-related.
After the tool is properly connected to the vehicle’s DLC, tap “OBD II” on the
Job menu. The tool will automatically start a check of the vehicle’s computer
to determine which type of communication protocol it is using. When the tool
identifies the computer’s communication protocol, a communication link is
established and then the screen will display the Monitor Status.
Fig. 5-12
Note: A PROTOCOL is a set of rules and procedures for regulating data
transmission between computers, and between testing equipment and
computers. Now ve different types of protocols (ISO 9141, Keyword 2000,
J1850 PWM, J1850 VPW and CAN) are in use by vehicle manufacturers.
Tap “OK”, the following function list appears.
1. Read Codes
This option is used to identify which section of the emission control system has
malfunctioned.
Note: Diagnostic Trouble Codes or Fault Codes can be used to identify
which engine systems or components that are malfunctioning. Never replace
a part based only on the DTC definition. Retrieving and using DTCs for
troubleshooting vehicle operation is only one part of an overall diagnostic
strategy. Follow testing procedures (in vehicle’s service manual), instructions
and owcharts to conrm the locations of the problem.
2. Erase Codes