Power Steering System Chevrolet Cobalt I

Fastener Tightening Specifications

Fastener Tightening Specifications

Scheme 1

Scheme 2

Electronic Power Steering (EPS) Control Module C1 Connector Part Information OEM: 10721337 Service: See Catalog 2-Way F 375 58 (BK) Pin Wire Color Circuit No. Function 1 RD/BK 642 Battery Positive Voltage 2 BK 1150 Ground

Electronic Power Steering (EPS) Control Module C2 Connector Part Information OEM: 15438391 Service: See Catalog 6-Way F 040 (GY) Pin Wire Color Circuit No. Function 1 TN/BK 2500 High Speed GMLAN Serial Data (+) (1) 2 TN 2501 High Speed GMLAN Serial Data (-) (1) 3 - - Not Used 4 BN/WH 2500 High Speed GMLAN Serial Data (+) (1) 5 BN 2501 High Speed GMLAN Serial Data (-) (1) 6 PK 1539 Run/Crank Ignition 1 Voltage

Electronic Power Steering Control Module (PSCM) C3 Connector Part Information 7123-4123-30 2-Way F (BU) Pin Wire Color Circuit No. Function + RD 5 Motor Control - BK 5 Motor Control

System Familiarization

Review the electric power steering (EPS) system operation in order to familiarize yourself with the correct system functions and operations. Refer to Power Steering System Description and Operation .

Visual/Physical Inspection

1. Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/cobalt/i-2004-2010/remont/electrical-component-locations/#wiring-systems-electrical-power-management__testing-for-intermittent-conditions-and-poor) in Wiring Systems.
2. Inspect for aftermarket components such as tires, or wheels which could affect the operation and/or performance of the power steering system.
3. Inspect the steering column for accident damage. Refer to «Steering Column Accident Damage Inspection»(/chevrolet/cobalt/i-2004-2010/remont/ignition-switchsteering-lock/#steering-wheel-steering-column) in Steering Wheel and Column.

System Diagnosis

After incorrect system operation has been verified and that aftermarket devices, or intermittent conditions are not the cause, begin the system diagnosis with the Vehicle Diagnostic System Check. The Vehicle Diagnostic System Check will provide the following information

1. The identification of the control modules that control the Power Steering System.
2. The ability of those control modules to communicate via the serial data circuit.
3. The presence of any stored diagnostic trouble codes (DTCs) in those control modules and there status.

The use of the Vehicle Diagnostic System Check will identify the correct procedure for diagnosing the malfunction and where the procedure is located. Refer to Diagnostic System Check - Vehicle in Vehicle DTC Information.

Scan Tool Data List

Scan Tool Data List

Circuit Description

The power steering control module (PSCM) receives a vehicle speed message from the powertrain control module (PCM) via the serial data circuit. The PSCM uses this vehicle speed message, and other inputs, to determine the desired amount of steering assist. At lower speeds, more assist is provided for easy turning during parking maneuvers. At higher speeds, less assist is provided for improved road feel and directional stability.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC C0000 Vehicle Speed Information Circuit

This vehicle has DTCs which include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC C0000

Conditions for Running the DTC

1. The ignition is ON.
2. DTCs U2100, U2105, 2107, or U2109 are not set.
3. Power Steering System voltage is between 6-16 volts.

Conditions for Setting the DTC

The PSCM receives an invalid vehicle speed message from the PCM.

Action Taken When the DTC Sets

1. DTC C0000 71 is stored in memory.
2. The DIC displays the POWER STEERING warning message.
3. Steering assist is set to a default level.
4. Poor return to center.

Conditions for Clearing the DTC

1. A current DTC will clear when the malfunction is no longer present.
2. A history DTC will clear after 100 consecutive malfunction-free ignition cycles.
3. Using a scan tool

Test Description

The number below refers to the step number on the diagnostic table.

1. 2: This step tests for the presence of vehicle speed related DTCs in the control module where the vehicle speed message originates.

DTC C0000

The power steering control module (PSCM) monitors the temperature of the Power Steering System. The PSCM uses voltage, current levels and input from an internal temperature sensor to calculate an estimated system temperature. If the PSCM detects a high system temperature event is occurring, the amount of assist is reduced to lower system temperature to prevent thermal damage to the power steering components.

This diagnostic procedure supports the following DTC

DTC C0176 System Thermal Error

This vehicle has DTCs which include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC C0176

Condition for Running the DTC

1. The ignition is ON, with the engine ON.
2. Power Steering System voltage is 9-16 volts.
3. Repetitive steering input is present.

The PSCM detects a high system temperature.

1. DTC C0176 54 is stored in memory.
2. Steering assist is reduced.

1. A current DTC will clear when the Power Steering System temperature returns to normal.
2. A history DTC will clear after 100 consecutive malfunction-free ignition cycles.
3. Using a scan tool

Diagnostic Aids

1. DTC C0176 54 does not indicate that a malfunction has occurred. Rather that the PSCM had to limit current to the power steering motor to avoid thermal damage to the Power Steering System components.
2. Inspect the under dash area around the steering column assembly. Ensure that no other components have come in contact with the power steering motor and module assembly, such as under dash insulation, or other electrical components.
3. Ensure that no steering components down stream of the power steering column assembly, such as ball joints, tie rod ends, universal joints, or the steering gear assembly, are mechanically binding.

The number below refers to the step number on the diagnostic table.

1. 2: This step tests if the high system temperature is driving condition related.

DTC C0176

The power steering control module (PSCM) continuously monitors the voltage and current levels being commanded to the power steering motor. The PSCM compares the commanded and feedback current levels to detect malfunctions in the power steering motor.

This diagnostic procedure supports the following DTC

DTC C0475 Electric Steering Motor Circuit

This vehicle has DTCs which include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC C0475

1. The ignition is ON, with the engine ON.
2. Power Steering System voltage is 9-16 volts.
3. Steering input is present.

A short to ground, short to voltage, or an open in the power steering motor, or the circuits to the motor.

1. A DTC C0475 00 is stored in memory.
2. The DIC displays the POWER STEERING warning message.
3. No steering assist is provided.

1. A current DTC will clear on the next malfunction-free ignition cycle.
2. A history DTC will clear after 100 consecutive malfunction-free ignition cycles.
3. Using a scan tool

DTC C0475

The power steering control module (PSCM) uses the steering shaft torque as its main input for determining steering direction and the amount of steering assist needed. The steering column has an input shaft from the steering wheel to the torque sensor and an output shaft from the torque sensor to the intermediate shaft coupler. The input and output shafts are separated by a section of torsion bar at the base of the steering column where the torque sensor is located. The torque sensor consists of a detecting coil, compensation coil and 3 detecting rings. Detecting ring 1 is fixed to the output shaft while detecting ring 2 is fixed to the input shaft. Both detecting rings have toothed edges that face each other. The detecting coil is positioned around the toothed edges of detecting rings 1 and 2. As torsional twist is applied to the steering column shaft's torsion bar when the steering wheel is turned, these toothed edges change alignment with each other which effects the magnetic characteristics around the detecting coil, changing the coils impedance thus changing the sensor's signal voltage input to the PSCM. The PSCM recognizes this change in detecting coil signal voltage as steering column shaft torque. The compensation coil is positioned around detecting rings 2 and 3, which do not change alignment with each other as the steering wheel is turned. This coil is used to compensate for the rotation of the steering shaft and also conditions that can effect circuit impedance, such as voltage, current and ambient temperature, for accurate torque detection.

This diagnostic procedure supports the following DTC

DTC C0545 Steering Wheel Torque Input Sensor

This vehicle has DTCs which include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC C0545

The ignition is ON.

The PSCM has not undergone the torque sensor calibration procedure.

1. DTC C0545 00 is stored in memory.
2. The driver information center (DIC) displays the POWER STEERING warning message.
3. Slight steering effort imbalance

1. A current DTC will clear on the next consecutive malfunction-free ignition cycle.
2. A history DTC will clear after 100 consecutive malfunction-free ignition cycles.
3. Using a scan tool

DTC C0545 4B will set upon the first ignition ON cycle after PSCM replacement.

DTC C0545

The body control module (BCM) contains the 2 amp EPS fuse. This fuse and the ignition 1 voltage circuit supply ignition voltage to the power steering control module (PSCM). This ignition voltage is used to wake up the PSCM. The PSCM receives a class 2 power moding message from the BCM to determine the position of the ignition switch. When a power mode message is received, the PSCM monitors the ignition 1 voltage circuit to detect if a short to voltage, short to ground, or an open exists.

This diagnostic procedure supports the following DTC

DTC C0845 Device Ignition 1 Circuit

This vehicle has DTCs which include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC C0845

The PSCM has 9-16 volts.

1. The class 2 power mode message indicates OFF, and the ignition 1 voltage circuit is shorted to voltage.
2. The class 2 power mode message indicates ON, and the ignition 1 voltage circuit is shorted to ground or open.
3. DTCs U1300 and U1301 are not set.

1. DTC C0847 is stored in memory.
2. The instrument panel cluster (IPC) message center displays the PWR STR warning message.
3. The EPS system is disabled.

1. A current DTC will clear when the malfunction is no longer present.
2. A history DTC will clear after 100 consecutive malfunction free ignition cycles.
3. Using a scan tool

The ignition 1 voltage circuit supplies several other control modules with ignition voltage. Before preceding with the diagnostic table below, ensure no other control modules that use the ignition 1 circuit for their ignition voltage supply have any ignition voltage malfunctions present, such as the sensing and diagnostic module (SDM) or the cruise control module (CCM). Refer to Power Distribution Schematics in Wiring Systems. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems for further diagnosis.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: Tests if the malfunction is intermittent.
2. 5: Tests if a short to ground exists in the ignition 1 voltage circuit, or in the PSCM.

DTC C0845

Scheme 3

The power steering control module (PSCM) has a discrete battery positive voltage supply circuit. The PSCM monitors the voltage level on this circuit to ensure the electric power steering (EPS) system has adequate voltage levels to perform the system functions.

This diagnostic procedure supports the following DTC

DTC C0895 Device Voltage

This vehicle has DTCs which include DTC symptoms. For more information on DTC symptoms, refer to DTC Symptom Description in Vehicle DTC Information.

DTC C0895

The ignition is ON.

EPS system battery voltage is less than 9.55 volts or greater than 17.5 volts.

1. DTC C0896 is stored in memory.
2. The instrument panel cluster (IPC) message center displays the PWR STR warning message.
3. Steering assist is reduced.

1. A current DTC will clear when EPS system voltage is 9.55-17.5 volts.
2. A history DTC will clear after 100 consecutive ignition cycles with EPS system voltage between 9.55 volts and 17.5 volts.

The scan tool can be used to view the number of times a low battery voltage incident has occurred. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems for further diagnosis.

The number below refers to the step number on the diagnostic table.

1. 2: Tests if the malfunction exists in the vehicles charging system.
2. 3: Tests if the malfunction is intermittent.

DTC C0895

1. Inspect for aftermarket devices which could affect the operation of the power steering system.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Rattle, Clunk, or Shudder Noise from the Power Steering System»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system)
2. «Increase in Effort While Turning Steering Wheel»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system__increase-in-effort-while-turning-steering)
3. «Poor Return of Steering Wheel»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system__poor-return-of-steering-wheel)
4. «Steering Wheel Surges/Jerks While Turning»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system__steering-wheel-surgesjerks-while-turning)

Rattle, Clunk, or Shudder Noise from the Power Steering System

Increase in Effort While Turning Steering Wheel

Increase in Effort While Turning Steering Wheel

Poor Return of Steering Wheel

Poor Return of Steering Wheel

Steering Wheel Surges/Jerks While Turning

Steering Wheel Surges/Jerks While Turning

Tools Required

J 24319-B Steering Linkage and Tie Rod Puller. See Special Tools .

Removal Procedure

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cobalt/i-2004-2010/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the front wheel. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/cobalt/i-2004-2010/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
3. Loosen the outer tie rod to inner tie rod jam nut.
4. Remove the tie rod to steering knuckle nut and discard.
5. Use the J 24319-B to separate the outer tie rod from the steering knuckle. See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system__special-tools) .
6. Remove the outer tie rod from the inner tie rod. Record the number of turns used in removal to aid in the installation.
7. Remove the outer to inner tie rod jam nut and discard.

Installation Procedure

1. Thoroughly clean the inner tie rod threads.
2. Install a new outer to inner tie rod jam nut.
3. Thread the outer tie rod onto the inner tie rod using the previously recorded thread count.
4. Install the outer tie rod to the steering knuckle.
5. Install a new outer tie rod nut. Tighten: Tighten the nut to 60 N.m (44 lb ft).
6. Install the front wheel. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/cobalt/i-2004-2010/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
7. Set the toe. Refer to «Front Toe Adjustment»(/chevrolet/cobalt/i-2004-2010/remont/wheel-alignment/#wheel-alignment-system__front-toe-adjustment) in Wheel Alignment.

J 22610 Keystone Clamp Pliers. See Special Tools .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cobalt/i-2004-2010/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the front wheel. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/cobalt/i-2004-2010/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
3. Remove the outer tie rod end. Refer to «Rack and Pinion Outer Tie Rod End Replacement»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system) .
4. Remove the outer to inner tie rod jam nut and discard.
5. Remove the outer steering gear boot spring clamp.
6. Using cutters, cut the inner steering gear boot clamp, remove and discard.
7. Disengage the steering gear boot from the steering gear and remove over the inner tie rod.
8. Inspect the sealing surfaces and threaded shaft portion of the steering gear and inner tie rod. The surfaces must be clean and free of debris.

1. Install a new clamp on the inner portion of the steering gear boot.
2. Apply grease from the service kit to the indicated locations.
3. Install the boot over the inner tie rod onto the steering gear.
4. Using the J 22610 , crimp the inner boot clamp on the steering gear housing. See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system__special-tools) .
5. Install the small spring clamp on the outer portion of the inner tie rod end.
6. Install a new outer to inner tie rod jam nut.
7. Install the outer tie rod end. Refer to «Rack and Pinion Outer Tie Rod End Replacement»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system) .
8. Install the wheel. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/cobalt/i-2004-2010/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
9. Set the toe. Refer to «Front Toe Adjustment»(/chevrolet/cobalt/i-2004-2010/remont/wheel-alignment/#wheel-alignment-system__front-toe-adjustment) in Wheel Alignment.

J 24319-B Steering Linkage and Tie Rod Puller. See Special Tools .

1. Turn the steering wheel to the straight ahead position and remove the key from the ignition.
2. Turn the wheel counter clockwise in order to lock the steering column in place.
3. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/cobalt/i-2004-2010/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
4. Remove the front wheels. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/cobalt/i-2004-2010/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
5. Remove the steering gear to intermediate shaft pinch bolt and discard.
6. Disconnect the intermediate shaft from the steering gear.
7. Remove both steering gear outer tie rod to knuckle nuts and discard the nuts.
8. Use the J 24319-B to separate the outer tie rods from the steering knuckles. See «Special Tools»(/chevrolet/cobalt/i-2004-2010/remont/manual-power-steering/#power-steering-system__special-tools) .
9. Remove the steering gear bolts.
10. Carefully remove the steering gear from the frame and the vehicle through the LH wheel opening.

1. Install the steering gear to the frame through the LH wheel opening.
2. Install the steering gear bolts. Tighten: Tighten the bolts to 110 N.m (81 lb ft).
3. Connect the intermediate shaft to the steering gear.
4. Install a new intermediate shaft pinch bolt. Tighten: Tighten the bolts to 34 N.m (25 lb ft).
5. Install the outer tie rods to the steering knuckles.
6. Install new outer tie rod nuts. Tighten: Tighten the bolts to 60 N.m (44 lb ft).
7. Install the front wheels. Refer to «Tire and Wheel Removal and Installation»(/chevrolet/cobalt/i-2004-2010/remont/wheel-tire-system/#tires-and-wheels) in Tires and Wheels.
8. Lower the vehicle.
9. Adjust the toe if necessary. Refer to «Front Toe Adjustment»(/chevrolet/cobalt/i-2004-2010/remont/wheel-alignment/#wheel-alignment-system__front-toe-adjustment) in Wheel Alignment.

The electric power steering (EPS) system reduces the amount of effort needed to steer the vehicle. The system uses the body control module (BCM), power steering control module (PSCM), torque sensor, discrete battery voltage supply circuit, EPS motor, serial data bus, and the instrument panel cluster (IPC) message center to perform the system functions. The PSCM, torque sensor, not the EPS motor are serviced separately from each other or from the steering column. Any EPS components diagnosed to be malfunctioning requires replacement of the steering column assembly, also known as the EPS assembly.

Torque Sensor

The PSCM uses a torque sensor as it's main input for determining the amount of steering assist. The steering column has an input shaft, from the steering wheel to the torque sensor, and an output shaft, from the torque sensor to the steering shaft coupler. The input and output shafts are separated by a torsion bar, where the torque sensor is located. The sensor consists of a compensation coil, detecting coil and 3 detecting rings. These detecting rings have toothed edges that face each other. Detecting ring 1 is fixed to the output shaft, detecting rings 2 and 3 are fixed top the input shaft. The detecting coil is positioned around the toothed edges of detecting rings 1 and 2. As torque is applied to the steering column shaft the alignment of the teeth between detecting rings 1 and 2 changes, which causes the detecting coil signal voltage to change. The PSCM recognizes this change in signal voltage as steering column shaft torque. The compensation coil is used to compensate for changes in electrical circuit impedance due to circuit temperature changes from the electrical current and voltage levels as well as ambient temperatures for accurate torque detection.

EPS Motor

The EPS motor is a 12 volt brushed DC reversible motor with a 58 amp rating. The motor assists steering through a worm shaft and reduction gear located in the steering column housing.

Power Steering Control Module (PSCM)

The PSCM uses a combination of torque sensor inputs, vehicle speed, calculated system temperature and the steering calibration to determine the amount of steering assist. When the steering wheel is turned, the PSCM uses signal voltage from the torque sensor to detect the amount of torque being applied to the steering column shaft and the amount of current to command to the EPS motor. The PSCM receives serial data from the engine control module (ECM) to determine vehicle speed. At low speeds more assist is provided for easy turning during parking maneuvers. At high speeds, less assist is provided for improved road feel and directional stability. The PSCM nor the EPS motor are designed to handle 58 amps continuously. The PSCM will go into overload protection mode to avoid system thermal damage. In this mode the PSCM will limit the amount of current commanded to the EPS motor which reduces steering assist levels. The PSCM also chooses which steering calibration to use when the ignition is turned ON, based on the production map number stored in the BCM. The PSCM contains all 8 of the steering calibrations which are different in relation to the vehicles RPO's. The PSCM has the ability to detect malfunctions within the EPS system. Any malfunction detected will cause the IPC message center to display PWR STR (or Power Steering) warning message.

Special Tools

Special Tools Illustration Tool Number/ Description J-24319-B Steering Linkage and Tie Rod Puller J-22610 Keystone Clamp Pliers

Scheme 4

Scheme 5

See also:
• Testing for Intermittent Conditions and Poor Connections
• Steering Column Accident Damage Inspection
• Diagnostic System Check - Vehicle
• DTC Symptom Description
• Diagnostic Trouble Code (DTC) List - Vehicle
• Control Module References
• Power Distribution Schematics
• Testing for Short to Ground
• Wiring Repairs
• Testing for a Short to Voltage
• Circuit Testing
• Connector Repairs
• Symptoms - Steering Wheel and Column
• Noise Diagnosis - Front Suspension
• Tire Inflation Pressure Specifications
• Lifting and Jacking the Vehicle
• Measuring Wheel Alignment
• Lower Ball Joint Replacement
• Diagnostic Starting Point - Engine Electrical
• Tire and Wheel Removal and Installation
• Fastener Notice
• Front Toe Adjustment
• Power Steering System Description and Operation
• Increase in Effort While Turning Steering Wheel
• Poor Return of Steering Wheel
• Steering Wheel Surges/Jerks While Turning
• Special Tools