Electronic-hydraulic auxiliary steering (EHZ) diagnosis, diagnostic fault code memory

AD46.80-W-4001B

Electronic-hydraulic auxiliary steering (EHZ) diagnosis, diagnostic fault code memory

10.8.00

Electronic-hydraulic auxiliary steering (EHZ) diagnosis previous knowledge

AD46.80-W-2001A

Notes on reading out the diagnostic fault code memory

AD46.80-W-2001-01B

Connect EHZ jumper plug

AD46.80-W-2001-03A



Switch on ignition



Teach-in electronic-hydraulic auxiliary steering (EHZ)

AR46.80-W-1110A

Diagnostic trouble code memory:

Flash code

Fault code

Possible cause/note

Remedy

1 time

LWS VA

 Steering angle sensor at the front axle

 Incorrect internal amplification factor (EHZ control unit)

Perform teach-in process again, if still faulty, install new electro-hydraulic auxiliary steering control unit.

2 times

LWS NLA

 Steering angle sensor at the auxiliary steering axle

 Incorrect internal amplification factor (EHZ control unit)

Perform teach-in process again, if still faulty, install new electro-hydraulic auxiliary steering control unit.

3 times

PY

 Centering circuit pressure sensor (PY)

 Incorrect internal amplification factor (EHZ control unit)

Perform teach-in process again, if still faulty, install new electro-hydraulic auxiliary steering control unit.

4 times

PX

 Steering circuit pressure sensor (PX)

 Incorrect internal amplification factor (EHZ control unit)

Perform teach-in process again, if still faulty, install new electro-hydraulic auxiliary steering control unit.

5 times

PX

 Steering circuit pressure sensor not connected

 Electrical fault: value too high
(> 4.5 V)

 Electrical fault: value too low
(< 0.5 V)

Check electrical connections.

6 times

PY

 Centering circuit pressure sensor not connected

 Electrical fault: value too high
(> 4.5 V)

 Electrical fault: value too low
(< 0.5 V)

Check electrical connections.

7 times

LWS VA

 Front axle steering angle sensor not connected

 Electrical fault: value too high
(> 4.5 V)

 Electrical fault: value too low
(< 0.5 V)

Check supply voltage and signal voltage.

8 times

LWS NLA

 Auxiliary steering axle steering angle sensor not connected

 Electrical fault: value too high
(> 4.5 V)

 Electrical fault: value too low
(< 0.5 V)

Check supply voltage and signal voltage.

9 times

SP051

 Release valve (Y77) in steering circuit at hydraulic control block not connected

Check electrical connections.

10 times

SP071

 Collecting valve (Y78) in the centering circuit (PY) at hydraulic control block not connected

Check electrical connections.

11 times

SP011

 Control valve (Y76) in the steering circuit (PX) at hydraulic control block not connected

Check electrical connections.

12 times

SP201

 Control valve (Y75) in the flow control system not connected

Check electrical connections.

13 times

SP011

 Control valve (Y76) in the steering circuit (PX) at hydraulic control block cannot be regulated

 Control valve (Y76) not electrically okay (resistance measurement)

Check electrical connections.

Check control valve for contamination.

14 times

SP201

 Control valve (Y75) in the flow control system cannot be regulated

 Control valve (Y75) not electrically okay (resistance measurement)

Check electrical connections.

Check control valve for contamination.

15 times

PY

 Centering circuit (PY) cannot be refilled in a predefined period of time (1.5 min.)

 Pressure in centering circuit cannot be built up

Perform teach-in process with increased idle speed.

Check hydraulic system for leaks

16 times

SP201

 Control valve (Y75) fault

 Check pressure build-up/pressure reduction in the centering circuit and steering circuit

 Hydraulic or mechanical fault

Perform teach-in process with increased idle speed.

Check hydraulic system for leaks

17 times

PX/PY

 Pressure sensors in the centering circuit and steering circuit interchanged

 Wiring interchanged or not okay

Check wiring

18 times

PX/PY

 Fault in the centering circuit and steering circuit

 Electrical fault: value too high
(> 4.5 V)

 Electrical fault: value too low
(< 0.5 V)

 Hydraulic fault: value too high or too low

Perform teach-in process with increased idle speed.

Check hydraulic system for leaks

19 times

PY

 Pressure in the centering circuit outside of the tolerance range (25 to 35 bar).

Release centering pressure (PY) via the pressure limiting valve.

20 times

Internal fault

 Internal fault in the EHZ control unit

Install new electro-hydraulic auxiliary steering control unit.

21 times

SP051/071

 Release valve (Y77) and collecting valve (Y78) interchanged

 Wiring interchanged or not okay (pressure build-up in the steering circuit on actuation of collecting valve (Y78) and release valve (Y77))

22 times

SP051/071

 Release valve (Y77) and collecting valve (Y78) are actuated simultaneously

Check wiring

23 times

LWS VA

 Front axle steering angle sensor

Center position outside of the tolerance range

Set steering angle sensor.

24 times

LWS NLA

 Auxiliary steering axle steering angle sensor

Center position outside of the tolerance range

Set steering angle sensor.

25 times

LWS VA

 Front axle steering angle sensor rotated or incorrectly installed

Rotate steering angle sensor by 90°.

26 times

LWS VA

 Front axle steering angle sensor

Correction factors outside of the tolerance range

Check steering angle sensor center position setting.

27 times

PY

 Pressure in the centering circuit is too low
(< 25 bar)

Check hydraulic system for leaks

28 times

LWS NLA

 Trailing axle steering angle sensor rotated or incorrectly installed

Check installation position of steering angle sensor, if necessary rotate steering angle sensor by 90°.

29 times

LWS NLA

 Auxiliary steering axle steering angle sensor

Correction factors outside of the tolerance range

Check steering angle sensor center position setting

30 times

PSM

 Faulty vehicle speed signal from the PSM module

 PSM module not connected

 Fault in the PSM module, function or parameterization not okay

Check parameterization in PSM module.

31 times

PY

 Excessive volume of air present in the centering circuit

 Collecting valve (Y78) leakage

 Internal or external leakage

Check hydraulic system for leaks

Repeat bleeding operation.

32 times

PY

 Pressure loss in the centering circuit pressure at the end of the bleeding test within

1.5 minutes < 3 bar

Bleed centering circuit (PY) and perform teach-in process.

33 times

LWS NLA

 Auxiliary steering axle regulation process
> 1.5 min.

Place auxiliary steered axle on turntable and check auxiliary steering for ease of movement.

Repeat teach-in process.

34 times

PY

 Pressure in centering circuit (PY) is > 6 bar when the engine is not yet running

Release pressure in centering circuit (PY) before performing teach-in process.

35 times

PX

 Pressure in steering circuit (PX) is > 6 bar when the engine is not yet running

Check wiring to pressure sensors.

36 times

PX/PY

 Correction factors are not stored in the electro-hydraulic auxiliary steering control unit

Repeat teach-in process.

If fault still present, try installing new electro-hydraulic auxiliary steering control unit.

37 times

D+

 Motor already running during first part of teach-in process.

Repeat teach-in process according to instructions.

38 times

PY

 Centering pressure (PY) is > 10 bar during the first part of the teach-in process

Release pressure in centering circuit (PY) before performing teach-in process.