P0506
P0506 - Idle Speed Performance Lower than Expected
For wiring diagrams, refer to.
Theory of Operation
The PCM evaluates the ability of the idle speed control system to achieve and maintain a steady idle by monitoring engine RPM during idle. If engine RPM is not within a calibrated deadband of target idle speed, a timer is started. If the timer reaches a maximum threshold without the RPM trending towards control, a fault is set.
• When Monitored: With the engine idling in drive, the brake applied, engine run time more than a minimum calibrated value, and no VSS, MAF/MAP, ECT, TPS, ETC, CKP sensor, fuel system, or injector DTCs present.
• Set Condition: The PCM detects that engine speed is 100 RPM or more less than target idle for 30 seconds. Two trip fault. Three good trips to turn off the MIL.
Test Step 1 - Active DTC
• It is possible for ETC DTCs to be set at the same time as this DTC. Proceed with this test only if the other DTCs that are present are ETC related, but clear them before proceeding. If any other DTCs are set, they must be diagnosed and repaired before continuing this test.
• Start the engine and allow it to reach operating temperature.
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in possible serious or fatal injury.
• With a scan tool, select view DTCs.
Is the status active for this DTC?
Yes
• Go to Test Step 2 => [ Test
Step 2 - Air Induction System ]
No
• Perform the Checking for an Intermittent DTC diagnostic procedure in Refer to => Non-DTC Based Diagnostics.
Test Step 2 - Air Induction System
Inspect the air induction system for the following problems:
• Restrictions - dirty air cleaner, foreign material trapped in the air intake tube, etc.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 3 => [ Test
Step 3 - PCV System ]
Test Step 3 - PCV System
Inspect the PCV system for the following problems:
• Restrictions - sticking valve, collapsed hoses or tubes, obstructed passages or ports, etc.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 4 => [ Test
Step 4 - Throttle Body Operation ]
Test Step 4 - Throttle Body Operation
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the throttle body and the PCM.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals.
• Refer to any technical service bulletins that may apply.
• Inspect the throttle body for carbon build up or other restrictions.
• Using a straight edge, verify that the throttle plate is not bent. If the throttle plate is bent, the throttle body must be replaced.
• Start the engine.
• While the engine is running, lightly tap on the ETC motor, and listen for the idle to change. If the idle changes, the throttle body must be replaced.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Go to Test Step 5 => [ Test
Step 5 - PCM ]
Test Step 5 - PCM
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the throttle body and the PCM.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals.
• Refer to any technical service bulletins that may apply.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test
No
• Replace and program the PCM.
• Perform the PCM Verification Test. Refer to => Non-DTC
Based Diagnostics. PCM Verification Test