Description
The Diagnostic System Check-Engine Controls is an organized approach to identifying a condition that is created by a malfunction in the engine control system. The Diagnostic System Check must be the starting point for any driveability concern. The Diagnostic System Check directs the service technician to the next logical step in order to diagnose the concern. Understanding and correctly using the diagnostic table reduces diagnostic time and prevents the replacement of good parts.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure determines the particular condition.
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This step stores the powertrain control module (PCM) diagnostic trouble code (DTC) information into the scan tools memory. Review the captured information at the end of the diagnostic procedure in order to catch the next DTC in the event there are multiple DTCs stored. It is beneficial to review the Freeze Frame/Failure Records data. Use this information in order to determine how frequently and how recently the DTC set. This information and other operating conditions when the DTC set may help diagnose an intermittent condition. Capturing the stored information preserves data that the PCM loses when the following occurs:
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The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
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If there are other modules with DTCs set, refer to the DTC list. The DTC list directs you to the appropriate diagnostic procedure.
If multiple powertrain DTCs are stored, diagnose in the following order of priority:
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This step is for areas that have an Inspection/Maintenance or emission testing program. The testing facility found one or more I/M system statuses not set.
| • | When you are instructed to clear DTCs. |
| • | The PCM connectors are disconnected. |
| • | The PCM is replaced during a diagnostic procedure. |
| • | Component level DTCs--Sensors, solenoids, relays etc. Multiple DTCs within this category should be diagnosed in numerical order starting with the lowest numbered DTC, unless otherwise directed. |
| • | System level DTCs--Misfire, fuel trim, catalyst etc. |
Step | Action | Yes | No | ||||||||||||||
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Important:
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1 | Install a scan tool. Does the scan tool power-up? | Go to Step 2 | Go to Scan Tool Does Not Power Up in Data Communications | ||||||||||||||
Does the scan tool communicate with all the listed control modules? | Go to Step 3 | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Communications | |||||||||||||||
3 | Attempt to start the engine. Does the engine start and idle? | Go to Step 4 | |||||||||||||||
4 | Select the DTC display function for the following modules:
Does the scan tool display any DTCs? | Go to Step 5 | Go to Step 9 | ||||||||||||||
With a scan tool, save or capture the Powertrain DTC information, Store Information. Did you complete the action? | Go to Step 6 | -- | |||||||||||||||
Does the scan tool display any DTCs which begin with a "U"? | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Communications | Go to Step 7 | |||||||||||||||
7 | Does the scan tool display DTC P0601, P0602, P0603, P0604, P0606, or P1621? | Go to Step 8 | |||||||||||||||
Does the scan tool display DTC P0560, P0562, P0563, P0621, P0622? | |||||||||||||||||
9 | Is the customer's concern with the automatic transmission? | Go to Powertrain On Board Diagnostic (OBD) System Check - Automatic Transmission | Go to Step 10 | ||||||||||||||
Is the customer's concern with Inspection/Maintenance (I/M) testing? | Go to Step 11 | ||||||||||||||||
11 |
Did you find and correct the condition? | System OK | Go to Intermittent Conditions | ||||||||||||||
