For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provide an overview of each diagnostic category.

### DTC Descriptor

DTC P050A 00: 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 P000A 00, P0010 00, P0016 00, P0068 00, P0106 00, P0107 00, P0108 00, P0116 00, P0117 00, P0118 00, P0119 00, P0121 00, P0123 00, P0171 00, P0172 00, P0201 00, P0202 00, P0203 00, P0204 00, P0222 00, P0261 00, P0262 00, P0264 00, P0265 00, P0267 00, P0268 00, P0270 00, P0271 00, P0335 00, P0336 00, P0340 00, P0341 00, P0365 00, P0366 00, P0443 00, P0459 00, P0496 00, P2088 00, P2089 00, P2100 00, P2101 00, P2122 00, P2123 00, P2127 00, P2128 00, P2138 00 are not set.

• | The battery voltage is greater than 10 V.

• | The engine speed is at idle.

• | The engine coolant temperature (ECT) is greater than -9.75°C (+14.45°F).

• | DTC P050A 00 runs continuously when the above conditions are met.

### Conditions for Setting the DTC

• | The actual idle speed is 175 RPM lower than the desired idle speed or 175 RPM greater than the desired idle speed during a cold start.

• | The above condition is present for 3 s.

### Action Taken When the DTC Sets

DTC P050A 00 is a Type B DTC.

### Conditions for Clearing the DTC

DTC P050A 00 is a Type B DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

• | Heated Oxygen Sensor Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

• | Using a scan tool compare the Desired Idle Speed to the actual engine idle speed.

• | Actual engine idle speed should be no greater than 175 RPM below the Desired Idle Speed.

• | Actual engine idle speed should be no greater than 175 RPM above Desired Idle Speed.

• | 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 system

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming