Diagnosis
The following table will diagnose the PCM controlled outputs from the output driver modules only. For diagnosis of the cooling fan circuit, refer to Electric Cooling Fan Diagnosis . For diagnosis of the cruise control module circuit, refer to Cruise Control Diagnosis . For specific system components and wiring refer to the Electrical Diagnosis and the Automatic Transaxle protion of the service manual for transmission related components.
Diagnostic Aids
| • | The scan tool has the ability to command certain components and functions ON and OFF. If a component or function does not have this capability, operate the vehicle during its normal function criteria to check for an open or shorted circuit. |
| • | An open or short to ground will appear in the open positions on the scan tool only when it is not commanded by the PCM or scan tool, while a short to voltage will appear in the short positions on the scan tool only while the component is being commanded by the PCM or scan tool. |
Test Description
The number(s) below refer(s) to the step number(s) on the Diagnostic Table.
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The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the fault occurred. The scan tool stores this data for later reference.
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A 1 in any of the positions indicates that an open or a short is present in the corresponding circuit for that position.
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Refer to the scan tool display art in this section in order to determine which circuit corresponds to which position of the scan tool display.
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An open or a short to ground will appear in the open positions on the scan tool only when not commanded by the PCM or the scan tool, while a short to voltage will appear in the short positions on the scan tool only while the component is being commanded by the PCM or scan tool.
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Proper operation of any component or function with no 1 in any of the positions indicates that system operation is normal at this time.
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A component or function that failed to operate at this point indicates that the malfunction is not on the PCM side of the circuitry. Go to the appropriate Automatic Transaxle, Electrical Diagnosis or to the diagnostic table of the malfunctioning component portion of the service manual for further diagnosis.
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The 1 going away after disconnecting the component electrical connector indicates that the component or the component side wiring is malfunctioning. If the scan tool indicates a fault after disconnecting the component electrical connector and verifying that no open or short is present in the circuit, then the PCM is malfunctioning.
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Reprogram the replacement PCM and the perform the crankshaft position system variation learning procedure. Refer to the latest Techline information for PCM programming and the Powertrain Control Module (PCM) for the crankshaft position system variation learning procedure.
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If no malfunctions are present at this point, refer to Diagnostic Aids for additional checks and information.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | |||
Install a scan tool. Is there a number 1 below any of the numbered positions in the Output Drivers? | -- | |||
Check for an open or for a shorted circuit in any corresponding position (circuit) that contained a number 1 and repair the circuit as necessary? Was a repair necessary? | -- | |||
Command the output being checked with a scan tool while watching the corresponding position for each circuit. Do any of the positions change to a 1? | -- | |||
Does the component or function operate when commanded? | -- | |||
Go to the appropriate Automatic Transaxle, Electrical Diagnosis or to the diagnostic table of the malfunctioning component portion of the service manual for any component that malfunctioned when commanded and make any necessary repairs. Is the action complete? | -- | -- | ||
7 | Repair the short to voltage in the corresponding circuit for the position (circuit) that displayed a 1. Is the action complete? | -- | -- | |
Disconnect the electrical connector to the component connected to the malfunctioning circuit. Is a number 1 still displayed in the corresponding Output Driver position? | -- | |||
Replace the PCM. Is the action complete? | -- | -- | ||
Operate the vehicle within the conditions under which the original symptom was observed. Does the system now operate properly? | -- | System OK Refer to Diagnostic Aids |
