Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Increase in Effort While Turning Steering Wheel
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you review the Power Steering System Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Power Steering System Description and Operation |
| 2 | Verify that there is an increase in effort while turning is present. Does the system operate normally? | System OK | Go to Step 3 |
| 3 | Check for the following tire related conditions: Incorrect tire inflation-Refer to Tire Inflation Pressure Specifications in Maintenance and Lubrication. Improper tire size Did you find and correct the condition? | Go to Step 10 | Go to Step 4 |
| 4 | Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Check for a binding or worn tie rod end. Is the tie rod binding or worn? | Go to Step 7 | Go to Step 5 |
| 5 | Check for a worn or binding intermediate shaft. Is the intermediate shaft worn or binding? | Go to Step 8 | Go to Step 6 |
| 6 | Check for a worn or binding steering gear. Is the steering worn or binding? | Go to Step 9 | System OK |
| 7 | Replace the outer tie rod end. Refer to Rack and Pinion Outer Tie Rod End Replacement . Did you complete the repair? | Go to Step 10 | |
| 8 | Replace the intermediate shaft. Refer to Intermediate Steering Shaft Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 10 | |
| 9 | Replace the steering gear. Refer to Power Steering Gear Replacement . Did you complete the repair? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Increase in Effort While Turning Steering Wheel
Poor Return of Steering Wheel
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you review the Power Steering System Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Power Steering System Description and Operation |
| 2 | Verify a poor return of the steering wheel is present. Does the system operate normally? | System OK | Go to Step 3 |
| 3 | Check for incorrect tire inflation. Refer to Tire Inflation Pressure Specifications in Maintenance and Lubrication. Did you find and correct the condition? | Go to Step 11 | Go to Step 4 |
| 4 | Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Check for a binding or worn tie rod end. Is the tie rod binding or worn? | Go to Step 8 | Go to Step 5 |
| 5 | Check for a worn or binding intermediate shaft. Is the intermediate shaft worn or binding? | Go to Step 9 | Go to Step 6 |
| 6 | Check for worn a or binding ball joint. Are the ball joints worn or binding? | Go to Step 10 | Go to Step 7 |
| 7 | Check for proper alignment of the front suspension. Refer to Measuring Wheel Alignment in Wheel Alignment. Did you complete the wheel alignment? | Go to Step 11 | |
| 8 | Replace the outer tie rod end. Refer to Rack and Pinion Outer Tie Rod End Replacement . Did you complete the repair? | Go to Step 11 | |
| 9 | Replace the intermediate Shaft. Refer to Intermediate Steering Shaft Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 11 | |
| 10 | Replace the ball joint. Refer to Lower Ball Joint Replacement in Front Suspension. Did you complete the repair? | Go to Step 11 | |
| 11 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Poor Return of Steering Wheel
Steering Wheel Surges/Jerks While Turning
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you review the Power Steering System Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Power Steering System Description and Operation |
| 2 | Verify that the steering wheel surges/jerks while turning. Does the system operate normally? | System OK | Go to Step 3 |
| 3 | Check for worn or binding front suspension components. Did you find and correct the condition? | Go to Step 15 | Go to Step 4 |
| 4 | Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Check for a binding or worn tie rod end. Is the tie rod binding or worn? | Go to Step 11 | Go to Step 5 |
| 5 | Check for a worn or binding intermediate shaft. Is the intermediate shaft worn or binding? | Go to Step 12 | Go to Step 6 |
| 6 | Check for worn a binding steering gear. Is the steering gear worn or binding? | Go to Step 13 | Go to Step 7 |
| 7 | Check for a worn or binding steering column. Is the steering column worn or binding? | Go to Step 14 | Go to Step 8 |
| 8 | Check for excessive heat in the EPS motor. Does the EPS appear to be overheated? | Go to Step 09 | Go to Step 10 |
| 9 | IMPORTANT: Do not perform excessive parking lot maneuvers during testing. Excessive parking lot maneuvers can cause the EPS motor to heat up. Allow the EPS motor to cool and retest the system.Did you find and correct the condition? | Go to Step 15 | Go to Step 10 |
| 10 | Check for low battery voltage. Refer to Diagnostic Starting Point - Engine Electrical in Engine Electrical. Did you find and correct the condition? | Go to Step 15 | System OK |
| 11 | Replace the outer tie rod end. Refer to Rack and Pinion Outer Tie Rod End Replacement . Did you complete the repair? | Go to Step 15 | |
| 12 | Replace the intermediate Shaft. Refer to Intermediate Steering Shaft Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 15 | |
| 13 | Replace the steering gear. Refer to Power Steering Gear Replacement . Did you complete the repair? | Go to Step 15 | |
| 14 | Replace the steering column. Refer to Steering Column Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 15 | |
| 15 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
| IMPORTANT |
|---|
| Do not perform excessive parking lot maneuvers during testing. Excessive parking lot maneuvers can cause the EPS motor to heat up. |
Steering Wheel Surges/Jerks While Turning
Tools Required
SA9164C Clamp Crimper. See Special Tools and Equipment .
EPS Motor
The EPS motor is a 12 volt brushed DC reversible motor with a 65 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 65 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 VIN. 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 the PWR STR (or Power Steering) warning message.