Circuit Description
Important:
• Only perform this system check if driveability complaints exist. • Search for applicable bulletins before proceeding with the diagnosis. • Do not turn OFF the ignition when performing this diagnostic table. • Do NOT clear the DTCs unless the diagnostic instructs you to do
so. • If there is a condition with the starter system, refer to
Diagnostic System Check - Engine Electrical
in Engine Electrical. • Verify that the battery is fully charged and the cables are clean
and tight. • Verify that the PCM grounds are clean, tight, and in the proper
location.
The Diagnostic System Check-Engine Controls is an organized approach to identifying conditions created by an electronic engine control system malfunction. This system check is the starting point for any driveability complaint diagnosis. Understanding, and using the table correctly will reduce diagnostic time, and will prevent the replacement of good parts.
Diagnostic Aids
| • | Inspect the following sensors for proper operation: |
| - | The engine coolant temperature (ECT) sensor--Look for an initial coolant temperature reading that is close to ambient, then observe the rise in temperature to the normal operating temperature while the engine is warming up. |
| - | The throttle position (TP) sensor--Look for proper sweep from 0 percent to 100 percent. |
| - | The manifold absolute pressure (MAP) sensor--Look for quick changes during changes in various engine loads. |
| - | The oxygen sensor (O2S 1)--Look for proper rich/lean and lean/rich sweeps in operation. |
| - | The idle air control (IAC) valve--Look for proper idle control and proper transition while operating the high load components such as the air-conditioning (A/C) control. |
| • | Inspecting the sensors for proper operation during warm-up can be a crucial step in correctly diagnosing any driveability concern. Careful observation of these sensors during engine warm-up may reveal a slow responding sensor or a sensor that malfunctions only within a small portion of its range. |
| • | Review any published service bulletins that relate to the exhibited symptoms or to components operation. |
| • | If multiple DTCs are stored, diagnose in the following order: |
| 1. | System voltage DTCs |
| 2. | PCM Error DTCs |
| 3. | Component level DTCs, or DTCs that indicate a malfunctioning part |
| 4. | System level DTCs, or DTCs that indicate a system malfunction. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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In order to correctly diagnosis any driveability malfunctions, the scan tool must be able to power-up.
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The diagnostic tables in this portion of the service manual are designed for use with a properly functioning scan tool. Serial data communication must be corrected before beginning any other diagnostic procedures. Class 2 serial data will not transmit if the system voltage is less than 9.0 volts or more than 16.0 volts.
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By storing the Freeze Frame/Failure Records on the scan tool, an electronic copy of the data is created when the malfunction occurred. This information is stored on the scan tool and can be referred to later. Type C DTCs do not store Freeze Frame data. If this option is not available, manually record the information for later reference.
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If multiple DTCs are stored, refer to Diagnostic Aids.
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After the engine is at normal operating temperature, comparison of actual control system data with the typical values is a quick way to determine if any parameter is not within limits. A base engine condition, such as advanced cam timing, may substantially alter sensor values.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Does the scan tool power-up? | -- | |||||||
Does the scan tool display PCM data? | -- | |||||||
3 | Start the engine. Does the engine start, and continue to run? | -- | ||||||
4 | With the scan tool, check the following modules for DTCs:
Does the scan tool display any PCM DTCs? | -- | ||||||
Record the Freeze Frame/Failure Records information with the scan tool. Did you complete the action? | -- | -- | ||||||
Verify if the following PCM DTCs are active: P0601, P0602, or P1621 Did any of these DTCs set? | -- | |||||||
7 | Did any BCM DTCs set? | -- | ||||||
8 | Is the customer's concern with the Automatic Transmission? | -- | ||||||
9 | Is the customer's concern with the Inspection/Maintenance (I/M) testing? | -- | ||||||
Are the display values normal or within typical ranges? | -- | |||||||
11 | If the customer's concern is a symptom, refer to the following tables:
Did you complete the action? | -- | System OK | Go to Intermittent Conditions |
