Service

Inspecting hydraulic fluid level

TRW

The hydraulic fluid level is inspected with the aid of the dipstick attached to the screw cap of the reservoir.

• hydraulic fluid cold: in the area of the bottom marking
• hydraulic fluid warm (from engine temperature of about 50 °C): about midway between bottom and top markings

KOYO

On the KOYO steering system as well the hydraulic fluid level is checked with the aid of a dipstick attached to the screw cap of the reservoir.

The conditions for inspecting the fluid level are identical to those of the TRW steering system. The dipstick of the KOYO steering system, however, is designed as a flat dipstick.

Servotronic warning lamp K92

After the ignition is switched on , the Servotronic warning lamp K92 lights up. An internal test cycle takes place during this time.

If the warning lamp does not go out after the engine is started and after completion of the test cycle, this is an indication that faults may be stored.

Faults may be defect in the electrical system.

Self-diagnosis

Diagnosis communication is performed over the CAN. The gateway transmits the signals from the CAN over the K wire.

Self-diagnosis relates to the electrical/electronic part of the power steering. The control unit detects faults during operation and stores them in the permanent memory. This information is retained even if the battery voltage is interrupted. Sporadic faults are not stored in the permanent memory.

The ignition must be switched on first before initiating self-diagnosis.

Self-diagnosis can be performed with the vehicle system tester V.A.G 1552, the fault reader V.A.G 1551 or with the vehicle diagnostic, testing and information system VAS 5051.

Self-diagnosis is initiated with the address word

• 44 Power steering.

Functions available:

• 01 Interrogate control unit version
• 02 Interrogate fault memory
• 05 Erase fault memory
• 06 End output
• 07 Code control unit
• 08 Read measured value block

Recognition features of the steering systems

The Diagnostic and Information Systems VAS 5051 and VAS 5052 can be used to recognize the version of the steering system fitted in the function “Vehicle self-diagnosis”. This is done by selecting address word “44 – Power steering” in the function “Vehicle self-diagnosis”. After this entry is made, the version of the steering system appears in the screen in the top right window, together with other information.

The illustration opposite shows the screen for a vehicle fitted with the TRW steering system.

This illustration shows the screen for a vehicle fitted with the KOYO steering system.