P050A

DTC P050A

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptor
DTC P050A
- Cold Start Idle Air Control System Performance




Circuit/System Description

The throttle actuator control (TAC) motor is controlled by the engine control module (ECM). The DC motor located in the throttle body drives the throttle blade. In order to decrease idle speed, along with spark and fuel delivery changes the ECM commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the ECM commands the throttle plate open allowing more air to pass the throttle plate. The catalytic converter must be warmed to efficiently reduce the emissions. The cold start strategy is to reduce the amount of time it takes to warm the catalytic converter. During a cold start, the engine idle speed is elevated to allow the catalyst to warm quickly.


Conditions for Running the DTC

* DTCs P0096, P0097, P0098, P0099, P0117, P0118, P0121, P0122, P0123, P0125, P0300, P0336, P0446, P0455, P0496, P2101, P2176 are not set.
* The startup engine coolant temperature (ECT) is between -10 and +40°C (+14 and +104°F).
* The barometric pressure (BARO) is more than 65 kPa.
* The engine is running.
* DTC P050A runs continuously when the above conditions are met.



Conditions for Setting the DTC

* The actual idle speed is 100 RPM lower than the desired idle speed or 200 RPM greater than the desired idle speed during a cold start.
* The above condition is present for 7 seconds.



Action Taken When the DTC Sets

DTC P050A is a Type B DTC.


Conditions for Clearing the DTC

DTC P050A is a Type B DTC.


Reference Information
Schematic Reference

Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

* Using a scan tool compare the desired engine idle speed to the actual engine idle speed.
* Actual engine idle speed should be no greater than 100 RPM below desired.
* Actual engine idle speed should be no greater than 200 RPM above desired.
* Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.



Circuit/System Testing

1. If there are any other DTCs set, diagnose those first.
2. Inspect for any condition that can reduce idle speed by increasing engine load.

* Incorrect torque converter clutch (TCC) operation
* Accessories that require additional torque to operate
* Excessive deposits in the throttle body
* Restricted exhaust
* Mechanical conditions that limit engine speed

3. Inspect for the following conditions:

* Vacuum leaks
* A faulty positive crankcase ventilation (PCV) valve




Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.