Steering - ZF System Fault Tracing And Repair

NO: 64-23
DATE G01-25-2007
MODEL: S60, V70, XC70, S80, XC90
MODEL YEAR:
2003- (XC90)
2004- (all other listed models)
SUBJECT: ZF Power Steering System Fault Tracing and Repair
REFERENCE: TNN 64-24; 64-09; TNN 64-20; TNN 64-21; VIDA

THIS TNN SUPERSEDES TNN 64-23 DATED 07-31-2006. A REFERENCE TO TNN 64-24 HAS BEEN ADDED, AND THE MODEL YEAR RANGE FOR THE S60/V70 HAS BEEN CORRECTED. PLEASE UPDATE YOUR FILES.

WARNING: These vehicles have pyrotechnical airbags and seat belt tensioners. The components in the SRS system must be treated very carefully during repair. This is to help prevent: 1.Personal injury when carrying out repairs 2.Damage to or malfunction of the SRS system.

Refer to VIDA (Information > Repair > General Safety Information) for SRS warnings, information, and instructions.

This Tech Net Note is designed to assist with overall identification and repair of various problems with ZF-manufactured steering systems. ZF steering gears were factory-equipped on the following models:

This TNN is divided into three major sections:
1. The first section, 'Overview', provides a simple description of the power steering system.
2. The second section, 'Description', defines the various problems, such as noise, leakage, and functionality.
3. The third section, 'Repair', defines the specific repairs for each Description.

The purpose of this TNN is to guide the technician through the proper diagnosis and repair of the ZF power steering system. As a general guideline, a complete customer description of the concern, followed by confirmation of that concern, are key.

The customer should be asked the following questions:
- What is the specific problem?
- How long has the problem existed?
- Is it intermittent or permanent?
- Is the steering complaint affected by any of the following conditions:
- Stationary vehicle or while driving (and at what speed)?
- Temperature (outdoor temperature and/or vehicle temperature)?
- Condition of the road surface?
- Engine speed?
- Steering wheel position?

Answers to these questions should be incorporated into the text on the Repair Order as much as possible.

If the complaint is noise-related, a thorough check of the vehicle's entire front end is necessary, with a focus on components which may be worn or loose, before repairing the steering system. Likewise, a fluid leak complaint should be verified by cleaning and testing the affected area first, before any disassembly is begun.

The Section Table of Contents below allows the technician to turn to the appropriate section of this TNN as needed.
It should not be necessary to read the entire TNN every time a steering-related repair is made.

Section 1

Overview
A simple description of the power steering system.

There are two types of steering gears: Standard power steering or electronically controlled power steering (ECPS). ECPS adapts power steering assistance based on vehicle speed.

Fluid is suctioned from the fluid reservoir (1) through the suction line (2) to the pump (3), which is a rotary vane pump. Pressure is increased in the pump through compression and supplies the steering gear (4) power steering fluid under pressure through the delivery line (8).

The power steering fluid then passes through the return line (10) [and optionally in some models, to the oil cooler (11)] and the return hose (9) back to the fluid reservoir.

The pump is mounted on the engine and is driven by the auxiliaries belt.

NOTE: The system is extremely sensitive to contaminants.

Section 2