DTC P2101, P2118, or P2119. Chevrolet Joy 2008

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 provides an overview of each diagnostic category.

### DTC Descriptors

DTC P2101: Idle Speed Control (ISC) Motor Control Circuit
DTC P2118: Idle Speed Control (ISC) System
DTC P2119: Idle Speed Control (ISC) System Performance

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
5-Volt Reference | P0122, P0222 | P0510, P2119 | P0122, P0222 | P0123, P0223 | --
Idle Motor Position Signal | P0222 | P2118 | P0222 | P0223 | --
Idle Motor Switch Signal | P0510 | -- | P0510 | -- | --
Throttle Position Sensor Signal | P0122 | P0510 | P0122 | P0123 | --
Idle Motor High Control | P2101, P2118 | P2101, P2118 | P2101, P2118 | P2101, P2118 | --
Idle Motor Low Control | P2101, P2118 | P2101, P2118 | P2101, P2118 | -- | --
Low Reference | -- | -- | P0123, P0223 | -- | --

### Typical Scan Tool Data

#### ISC Command

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: ISC Command 30%
Idle Motor High Control | -40% | 0% | 0%
Idle Motor Low Control | 0% | 0% | -40%

### Circuit/System Description

The throttle body assembly uses an idle speed control (ISC) system that contains motor, throttle position (TP) sensor, motor position sensor, and an idle switch. The ISC system is used to control engine speed at idle. The engine control module (ECM) uses high and low control circuits to control the ISC motor. A 5-volt reference and low reference supplied by the ECM is shared by both the TP and motor position sensors. The TP and motor position sensors each have a signal circuit to feedback voltage to the ECM. The ECM commands the ISC motor by pulse width modulating the voltage on the high and low control circuits to adjust the throttle angle for idle speed control. The motor position sensor is used by the ECM to monitor the position of the ISC motor for idle operation. The TP sensor is used by the ECM to monitor the position of the throttle blade. An idle switch is used by the ECM to monitor when the throttle blade is at rest position to allow the ISC motor to control idle operation. With the throttle blade at the rest position, the idle switch will be closed. When the throttle blade is opened, the idle switch will be open.

The ISC system consist of the following circuits:

• | A 5-volt reference

• | Idle motor high control

• | Idle motor low control

• | Idle motor position signal

• | Idle motor switch signal

• | Low reference

• | Throttle position sensor signal

### Conditions for Running the DTC

#### P2101 and P2118

• | The engine is running.

• | The ISC motor angle is between 0.235-5.6 degrees.

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

#### P2119

• | Ignition is ON.

• | The DTC runs continuously when the above condition is met.

### Conditions for Setting the DTC

#### P2101 or P2118

The ECM has commanded a duty cycle of the ISC motor greater than 59.5 percent or less than or equal to -70 percent for 10 seconds.

#### P2119

The ECM detects the learned lower and upper limits exceed the actual lower and upper limits.

### Action Taken When the DTC Sets

DTC P2101, P2118, and P2119 are Type B DTCs.

### Conditions for Clearing the DTC

DTC P2101, P2118, and P2119 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Description and Operation

Idle Speed Control System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | 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

1. Ignition ON, command the ISC motor ON with a scan tool. The ISC motor position sensor percentage should fluctuate between 3-5 percent.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Verify the following conditions do not exist:

• | The throttle body is not damage or modified

• | Vacuum leaks

• | A restricted air intake system

• | Excessive deposits on the throttle plate or bore

• | The throttle shaft for binding

• | The throttle linkage or the throttle cable for binding

• | Incorrectly installed positive crankcase ventilation (PCV) valve or hose

• | A malfunctioning PCV valve

⇒ | If you find any of the above conditions, repair as necessary.

2. Ignition OFF, disconnect the harness connector at the ISC motor.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and ground.

⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM.

4. Test for less than 0.3 volt between the high control circuit terminal 5 and 12 volts.

⇒ | If greater than the specified range, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

Important: Use the AC volt scale on the DMM. The millivolt scale will produce an inaccurate reading.

5. Engine running, test for 30-40 hertz on the AC scale between the high control circuit terminal 5 and ground.

⇒ | If not within the specified range, test the high control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

6. Ignition OFF, verify that a test lamp does not illuminate between the low control circuit terminal 1 and 12 volts.

⇒ | If test lamp illuminates, test the low control circuit for a short to ground. If the circuit tests normal, replace the ECM.

7. Test for less than 0.3 volt between the low control circuit terminal 1 and the ground.

⇒ | If greater than the specified range, test the low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

8. If all circuits test normal, test or replace the ISC motor.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the ISC motor.
2. Test for 3-6 ohms of resistance between the high control terminal 5 and the low control terminal 51.

⇒ | If not within the specified range, replace the ISC motor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Throttle Body Assembly Replacement

• | Control Module References for ECM replacement, setup, and programming