The Tech 1 scan data listed in this table may be used for comparison after completing the On-Board Diagnostic System Check and finding the on-board diagnostics functioning properly with no diagnostic codes displayed. The "Typical Tech 1 Data Values" are an average of display values recorded from normally operating vehicles and are intended to represent what a normally functioning system would display. The values you get may vary due to low battery charge or other reasons, but they should be very close.

NOTE: A SCAN TOOL THAT DISPLAYS FAULTY DATA SHOULD NOT BE USED, AND THE PROBLEM SHOULD BE REPORTED TO THE MANUFACTURER. THE USE OF A FAULTY SCAN TOOL CAN RESULT IN MISDIAGNOSIS AND UNNECESSARY PARTS REPLACEMENT.

Only the parameters listed below are used in this manual for diagnosis. If a scan tool reads other parameters, the values are not recommended by General Motors for use in diagnosis. For more description on the values and use of the scan tool to diagnosis VCM inputs. If all values are within the range illustrated, refer to Diagnosis By Symptom. Testing and Inspection

TEST UNDER FOLLOWING CONDITIONS:
^ Engine at Operating Temperature

^ Engine Idling in "Closed Loop"

^ Closed Throttle

^ Park/Neutral

^ All Accessories "OFF"

Typical Scan Tool Data Values:

Part 1 of 2

Typical Scan Tool Data Values:

Part 2 of 2

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Engine Data 1

Typical Scan Tool Data Values:

Typical Scan Tool Data Values:

Use the Manual With the Right Hardware

When to See a Mechanic

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