Symptom Chart - Steering System and NVH

Select a symptom to see recommended actions 

A Module Cannot Communicate With The PSCM

• NOTE: Service Information diagnostics for another module not communicating with the PSCM must be carried out prior to entering this test. REFER to General Information for an index of all DTC charts and follow the diagnostics for the DTCs present.

  Possible Source	Action
  Fuse(s) Wiring, terminals or connectors HS-CAN concern PSCM	Go to PINPOINT TEST A

The PSCM Cannot Communicate With The Diagnostic Scan Tool

• NOTE: Diagnostics in Module Communications Network must be carried out before proceeding with this test.

  Possible Source	Action
  Fuse(s) Wiring, terminals or connectors HS-CAN concern PSCM	Go to PINPOINT TEST A

Open PSCM Fuse(s)

• There are 2 power sources for the PSCM, the high current power steering fuse, and the low current power steering fuse. Refer to the Power Steering Controls to review the PSCM circuit for both the high current and low current fuse locations as well as the associated power and ground wiring. Open power steering fuses can occur when the power or ground wiring is shorted against another component or water intrusion in the respective connectors or connections.

  Possible Source	Action
  Fuse(s) Wiring, terminals or connectors	Go to PINPOINT TEST A

Unable To Replicate Customer's Intermittent Assist Concern During A Test Drive

• Customers may report an intermittent power steering concern that may not replicate during a test drive session. TSBs, SSMs or DTCs may exist indicating the likely root cause. Retrieve all DTCs for the vehicle, as well as TSBs, and SSMs.

  Possible Source	Action
  If lost communication or voltage DTCs exist in the PSCM or other vehicle modules, possible sources can be: Fuse(s) Wiring, terminals or connectors HS-CAN concern	Go to PINPOINT TEST A
  If DTCs other than lost communication or voltage exist in the PSCM or other vehicle modules, the possible sources can be: Module internal fault - PSCM Module internal fault - other modules	REFER to the appropriate DTC Chart and CARRY OUT the diagnostics listed for the DTC.
  If no DTCs are present in the PSCM or other vehicle modules, the concern could be indicated by a TSB or a SSM. TSB existing for this concern SSM exists for this concern	CHECK OASIS for associated TSBs and SSMs. FOLLOW all TSB and SSM instructions. If there are no DTCs present and there are no TSBs or SSMs associated with this concern and the concern cannot be verified, RETURN the vehicle to the customer.

Message Center Displays POWER STEERING ASSIST FAULT

• NOTE: This message appears when a condition has been detected in the EPAS system requiring the PSCM to disable the system (remove assist) to help prevent the system from sustaining any possible damage. This message (and related symptom) may be cleared when the ignition key is cycled and may not be present at the time of diagnosis.

  Possible Source	Action
  DTCs present in the PSCM	Go to PINPOINT TEST KC

Message Center Displays SERVICE POWER STEERING

• NOTE: This message appears if a condition exists (high friction for example) putting extra load on the EPAS gear. Steering assist remains for the current ignition cycle, but with a reduced level of assist. If the ignition is turned OFF and then back ON, SERVICE POWER STEERING NOW appears in the message center and steering assist is removed until the condition is repaired.

  Possible Source	Action
  DTCs present in the PSCM	Go to PINPOINT TEST KC

Message Center Displays SERVICE POWER STEERING NOW

• NOTE: This message appears when a condition has been detected in the EPAS system requiring the PSCM to disable the system (remove assist) to help prevent the system from sustaining any possible damage. This message (and related symptom) cannot be cleared until the condition is repaired.

  Possible Source	Action
  DTCs present in the PSCM	Go to PINPOINT TEST KC

Excessive Steering Wheel Play

• Excessive steering wheel play is a condition in which there is too much steering wheel movement before the wheels move. A small amount of steering wheel free play is considered normal.

  Possible Source	Action
  Steering column shaft/U-joints Loose, damaged or worn inner or outer tie rods Steering gear internal failure	Go to PINPOINT TEST G

Front End Noise - During Acceleration (Tip-In) Or Deceleration (Tip-Out) May Occur With Braking

• Noises when accelerating or decelerating involve parts which move during an acceleration tip-in (pressing foot on gas pedal) or parts which move during deceleration tip-out (when taking foot off gas pedal). These noises are not typically associated with the steering gear.

  Possible Source	Action
  Steering shaft slip joints or lower input shaft (requires lubrication) Roll restrictor Powertrain mounts Exhaust heat shield (tinny rattle) Exhaust isolators and brackets Subframe mounts Engine to chassis wiring, tubes, brackets (loose or out of position) Halfshafts (if equipped) Mid-shaft bearing (right-side halfshaft)	Go to PINPOINT TEST AE

Front End Noise - During Braking

• NOTE: If the noise occurs while braking AND during tip-in or tip-out, this is not typically a steering gear related noise.
• Noises when braking involve parts which move during braking.

  Possible Source	Action
  Caliper anchors, calipers or brake pads Top strut mount or bearings (if equipped) Lower control arm attachment to sub frame bushings and bolts Engine to chassis wiring, tubes or brackets (loose or out of position) Powertrain mounts or engine roll restrictor mounts Exhaust isolators or brackets Steering shaft slip joints Subframe mounts	Go to PINPOINT TEST AE

Front End Noise - Driving Straight On Smooth Roads

• NOTE: Wheel hub bearings can produce noise after achieving 56 km/h (35 mph) while driving straight if they are worn.
• Front end noises while driving straight involve parts which rotate continuously while the road wheels are rotating. Typically not a steering gear.
• Noises can also be caused by loose or un-retained parts affected by wind.

  Possible Source	Action
  Possible Rotating Sources: Axle shafts or halfshafts Carrier bearing (noise is typically felt through the console) Drive shafts Transfer case assembly (if equipped) Wheel hub and wheel bearings (typically higher speeds) Possible Wind Sources: Air dams Heat shields Radiator ducts or shields Wheel well splash shields	Go to PINPOINT TEST L

Front End Noise - Over Bumps, Rough Roads, Dips, Depressions Or When Entering A Driveway

• Noises over bumps and rough roads involve parts which move and contact during an up and down motion.

  Possible Source

  Action

  Jounce bumper Stabilizer bar insulators or links Front shock brackets or strut mounts Loose steering gear tie rods Loose steering gear bolts Loose front brake calipers or pins Loose lower control arm-to-subframe bolts or bushings Loose ball joint Loose exhaust heat shield, isolators or brackets Subframe to body attachments points Upper or lower steering shaft Internal or external steering gear stops

  Go to PINPOINT TEST AC

Front End Noise - Turning At Slow Speeds Or During Parking Lot Maneuvers

• Exterior front end noises when turning at slow speeds involve parts which move, rotate or make contact during a partial or full turn. Please note whether the vehicle has column mounted EPAS, steering gear mounted EPAS or adaptive steering.

Lack of Assist, Inconsistent or Intermittent Assist

• NOTE: There are multiple conditions (overheating protection, high voltage, low voltage, etc.) which result in limited or reduced assist from the EPAS system. Address all existing PSCM DTCs prior to diagnosing any assist symptoms.
• NOTE: If the steering wheel is held at the end of travel for more than 2 seconds, the PSCM noticeably reduces assist to the EPAS gear. This is a normal condition programmed into the PSCM to protect the system from permanent damage.
• Lack of assist or inconsistent assist is experienced when the steering wheel effort is higher than normal. Hard steering can remain constant through the full turn or occur near the end of a turn. Intermittent assist is experienced when the steering wheel effort is normal, then high, then normal, intermittently, causing a notchy steering feel.
• If equipped, active park assist can only be activated if the steering system is providing full steering assist. If the active park assist system is currently in use and the steering system experiences a partial or non-assist event, active park assist is deactivated.
• If equipped, the lane departure warning system can only be activated if the steering system is providing full steering assist. If the lane departure warning system is currently in use and the steering system experiences a partial-assist or non-assist event, lane departure warning is deactivated.

Noise When Turning - Noticed More In The Interior

• Interior cabin noises involve parts moving or contacting during a steering wheel turn or interior parts moving or contacting during steering column tilt or telescopic operations.

  Possible Source	Action
  Steering column shrouds Steering shafts and steering shaft joints Steering shaft boots or seals Clockspring (when lubricant on the clockspring is dry or drying) Steering column tilt or telescoping motor (if equipped) Shifter cables (if equipped) Column EPAS motor (if equipped) Adaptive front steering motor (if equipped)	Go to PINPOINT TEST AD

Poor Returnability or Sticky Steering

• NOTE: Before continuing with the pinpoint test, compare the vehicle steering feel and returnability with a like vehicle and confirm there is a concern present. If the feel or returnability matches the comparison vehicle there is no fault. If the feel or returnability does not match the comparison vehicle continue with the diagnosis.
• Poor returnability and sticky steering is used to describe the poor return of the steering wheel to center after a turn or steering correction is completed.

  Possible Source	Action
  Under inflated or mismatched tires Misaligned steering column shrouds Binding lower steering column shaft coupling/U-joint Loose, damaged or worn inner or outer tie rods Binding suspension components Binding steering gear Binding steering gear bearing(s) Binding steering column shaft dash panel seal Alignment/suspension	Go to PINPOINT TEST I

Steering System Pull, Drift or Wander

• NOTE: The EPAS system is designed to compensate for some steering issues (drift, pull, wander, etc.). If the steering issue is severe enough the steering wheel may become off center due to system compensation.
• A vehicle-related drift or pull, on a flat road, can cause a consistent deviation from the straight-ahead path and require constant steering input in the opposite direction to counteract the effect.
  • Drift or pull can be induced by conditions external to the vehicle, such as wind or road camber.
  • Drift describes what a vehicle with this condition does with the hands off the steering wheel.
  • Pull is described as a tugging sensation on the steering wheel felt by the driver, which must be overcome to keep the vehicle going straight.
  • Wander is the tendency of the vehicle to require frequent, random left and right steering wheel corrections to maintain a straight path down a level road.

  Possible Source	Action
  Alignment Tire(s) Suspension components Steering column shaft/U-joints Steering column Steering gear mounts Steering gear	Go to PINPOINT TEST H

Steering Wheel Vibrates or Resists Turning

• The steering wheel can vibrate or shake as well as resist turning into the next lane when the turn signals are not used to change lanes. This may be a normal operation of the Lane Keeping Assist feature. Determine if the vehicle is equipped with the Lane Keeping Assist feature and educate the customer how the feature is activated, de-activated and properly used. Verify the vibration and turning resistance is no longer present when the Lane Keeping Assist feature is de-activated.
  • Refer to the following documents online in the Professional Technician Society web site.

  Possible Source	Action
  Owner's Literature	SEE DRIVING AIDS section. READ about Lane Keeping System.
  Owner's Literature: Quick Reference Guide	SEE FUNCTION section. READ about Lane Keeping System.
  Lane Keeping Reference Guide (all vehicles)	Released for sales and service on January 2015.