System chart - Steering System and NVH

WARNING: This page is about a different car, the 2014 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: NVH symptoms should be identified using the diagnostic tools that are available. For a list of these tools, an explanation of their uses and a glossary of common terms, refer to NOISE, VIBRATION & HARSHNESS . Since it is possible any one of multiple systems may be the cause of a symptom, it may be necessary to use a process of elimination type diagnostic approach to pinpoint the responsible system. If this is not the causal system for the symptom, refer back to NOISE, VIBRATION & HARSHNESS for the next likely system and continue diagnostics.

Select a symptom to see recommended actions

Message center displays POWER STEERING ASSIST FAULT

NOTE: This message will appear when a condition has been detected in the EPAS system that requires 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 diagnostics.

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

Message center displays SERVICE POWER STEERING

NOTE: This message will appear if a condition exists (high friction for example) that puts extra load on the EPAS gear. Steering assist will remain 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 will appear on the message center and steering assist will be removed until the condition that caused the message to appear 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 will appear when a condition has been detected in the EPAS system that requires the PSCM to disable the system (remove assist) to help prevent the system from sustaining any possible damage. This message (and related symptom) will not clear until the condition that caused the message to appear has been 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

Lack of assist or inconsistent assist

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.
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.
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. It is important to know the difference between hard steering/lack of assist and poor returnability/sticky steering.
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.

Possible Source	Action
Fuse(s) Wiring, terminals or connectors Suspension components Steering gear internal failure Loose, damaged or worn inner or outer tie rods	GO to PINPOINT TEST I

No communication with the PSCM

Possible Source	Action
Fuse(s) Wiring, terminals or connectors HS-CAN Steering gear	REFER to MODULE COMMUNICATIONS NETWORK to diagnose the no communication concern.

Poor returnability/sticky steering

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.
NOTE: Before continuing with the diagnostic procedures, compare the vehicle steering feel/returnability with a like vehicle and confirm there is a concern present.
- NOTE: If the feel/returnability matches the comparison vehicle there is no fault.
- NOTE: If the feel/returnability does not match the comparison vehicle continue with the diagnosis.

Possible Source	Action
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/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.
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.
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.

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

Feedback (rattle, chuckle or knocking noise) - roughness is felt in the steering wheel when driven over rough surfaces

Possible Source	Action
Steering column shaft/coupling bolts are loose	TIGHTEN the bolts to specification. REFER to STEERING COLUMN .
Steering column shaft/coupling joints damaged or worn	INSTALL a new steering column shaft. REFER to STEERING COLUMN .
Loose, damaged or worn inner or outer tie rods	GO to PINPOINT TEST J
Damaged steering gear bellows boots	GO to PINPOINT TEST K
Steering gear insulators or mounting bolts loose or damaged	If the mounting bolts are loose, INSTALL new bolts and TIGHTEN to specification. REFER to SPECIFICATIONS . If the steering gear insulators are damaged or missing, INSTALL a new EPAS gear. REFER to Steering Gear .

Grinding noise or gravely feel

Possible Source	Action
Damaged steering gear bellows boots	GO to PINPOINT TEST K

Shimmy

Possible Source	Action
Loose, damaged or worn inner or outer tie rods	GO to PINPOINT TEST J

Steering column squeaks, clicks or grinds

Possible Source	Action
Loose or misaligned steering column shrouds	TIGHTEN the steering column shroud screws.
Steering wheel rubbing against steering column shrouds	ALIGN the steering column shrouds.

Steering gear clunk occurs only while cornering over a bump (can be temperature sensitive)

NOTE: Some noise when turning into the steering stops is normal.

Possible Source	Action
Steering gear insulators or mounting bolts loose or damaged	If the mounting bolts are loose, INSTALL new bolts and TIGHTEN to specification. REFER to SPECIFICATIONS . If the steering gear insulators are damaged or missing, INSTALL a new EPAS gear. REFER to Steering Gear .
Steering gear has reached the end of travel and is contacting the steering stops	COMPARE to other EPAS vehicles. If the noise is excessive, INSPECT the outer tie rods and suspension ball joints. TIGHTEN or INSTALL new as necessary.

Steering wheel is off center

Possible Source	Action
Alignment Steering gear	GO to PINPOINT TEST H

Whirring or whine noise that gets louder with increased steering wheel speed

NOTE: Some amount of noise from the EPAS gear is considered normal.

Possible Source	Action
Grounded or loose steering column shaft dash panel seal	REPAIR or INSTALL a new dash panel seal as necessary. REFER to STEERING COLUMN SHAFT .
Steering gear	Compare to other EPAS equipped vehicles. If the noise is excessive, INSTALL a new EPAS gear. REFER to Steering Gear .