Diagnostic Circuit Check
SCAN DATA
| Scan Position | (1) Data Value | ||||||
|---|---|---|---|---|---|---|---|
| A/C | Off (On With A/C Requested) | ||||||
| Battery | 13.5-14.5 Volts | ||||||
| BLM (Block Learn Memory) | 118-138 Counts | ||||||
| Coolant Temperature | 185-221°F (85-105°C) | ||||||
| IAC | 1-50 Counts | ||||||
| INT (Integrator) | Varied Amount of Counts | ||||||
| Knock Signal | No | ||||||
| MAP | (2) 1-2 Volts | ||||||
| Open/Closed Loop | Closed Loop (Open At Idle) | ||||||
| Oxygen Sensor | (3) .1-.9 Volt | ||||||
| Oxygen Sensor Cross Counts | Greater Than One | ||||||
| RPM | 550-750 RPM | ||||||
| Rich/Lean Flag | Varies | ||||||
| Torque Converter Clutch | Off (On With TCC Requested) | ||||||
| TPS | .42-.54 Volt | ||||||
| VSS | 0 MPH | ||||||
|
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Diagnostic circuit check will identify problem created by Electronic Engine Control System (EECS) malfunction. It is the starting point for diagnosis. This check will direct you to the next logical step in diagnosing the complaint.
After completing diagnostic circuit check and finding on-board diagnostics functioning properly with no trouble codes displayed, use appropriate SCAN DATA table for comparison.
Data values must be taken under these conditions:
- Engine at normal operating temperature.
- Engine running at idle.
- Vehicle in Park or Neutral.
- System in closed loop.
The values are an average of displayed values recorded from normal operating vehicles. Values represent what a normal functioning system would typically display.
NOTE:
Only parameters supplied by manufacturer are used in this article. If a scan tester reads other parameters, values are not recommended by manufacturer for diagnostic use. A scan tester displaying faulty data should not be used, or misdiagnosis will occur. Report problem to scan tester manufacturer.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- This step checks if ECM can provide a ground path for CHECK ENGINE light. This is a bulb check.
- This step checks if ECM can perform internal diagnostics.
- This step checks if ECM can supply serial data for scan tester.
- This step verifies scan data.
- This step checks whether ECM or electrical system is cause of no start.
- This step checks ECM memory for codes to aid in diagnosis.