5.2 - Acceleration skid control (ASR) 23 - Test programme - electrical Testing, Model 124 with module box, Model 129 with module box up to 05/94, Model 140 up to 05/94

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 1.0 

ASR control unit (N30/1)

Voltage supply

Terminal 87 ASR

N30/1



32   .68

(2.32) (1.27)

25   .68

(2.25) (1.27)

40   .68

(2.40) (1.27)

Ignition: ON

11-14 V

 1.1

 1.1

Voltage supply from base module (N16/1)

N30/1

W16 

W16/1  .68

W27 (1.27)

Ignition: ON

11-14 V

Fuse (F1) on N16/1

1.1 or 1.2  23

Cables

 1.2

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 1.2

Ground cable

N30/1



Model 124

W27  .32

(1.32)

W16  .25

(2.25)

W16  .40

(2.40)

Ignition: OFF

<1 W

Cables

Model 124

Ground, component compartment (W16, figure 5)

Ground, bracket holder module box (W27, figure 5)

Model 129

W27  .32

(1.32)

W27  .25

(2.25)

W27  .40

(2.40)

Model 129

Ground, power ground (in right footwell, W27, figure 6)

Model 140

W16/1  .32

(1.32)

W16/1  .25

(2.25)

W16/1  .40

(2.40)

Model 140

Ground, right spring dome (W16/1,
figure 3)

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 2.0

ABS failure indicator (A1e17)

N30/1



40    76

(2.40) (1.35)

Ignition: ON

Engine: Idling

<2 V

A1e17: ON

10-14 V

A1e17: OFF

A1e17

 2.1

Read out fault memory  12

Cables

ASR control unit (N30/1)

 2.1

Diode in solenoid valve relay (A7/3k1)

-

Engine: OFF

Disconnect N30/1 from contact box

Ignition: ON

Engine: Idling

ABS failure indicator: ON

ABS failure indicator: ON

Cables

A7/3k1

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 3.0

ASR indicator lamp (A1e22)

N30/1



40    70

(2.40) (1.29)

Ignition: ON

Engine: Idling

<2 V

A1e22: ON

10-14 V

A1e22: OFF

A1e22

 3.1

Read out fault memory  12

Cables

ASR control unit (N30/1)

 3.1

Diode in solenoid valve relay (A7/3k1)

-

Ignition: OFF

Disconnect N30/1 from contact box

Ignition: ON

Engine: Idling

A1e22: ON

A1e22: ON

Cables

A7/3k1

 4.0

ASR function indicator (A1e21)

N30/1



78    68

(1.37) (1.27)

Ignition: ON

Engine: Idling

A1e21: ON

10-14 V

A1e21: OFF

<2 V

Cables

A1e21

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 5.0

Diagnosis output

N30/1



40    57

(2.40) (1.16)

Ignition: ON

10-14 V

Cables

ASR control unit (N30/1)

 6.0

Voltage, terminal 61e

N30/1



40    66

(2.40) (1.25)

Ignition: ON

Engine: Idling

<1 V

11-14 V

Cables

Alternator (G2)

 7.0 

Solenoid valve relay

(A7/3k1)

Activation

Monitoring

N30/1



27    7

(2.27) (2.7)

N30/1



40    1

(2.40) (2.1)

40    21

(2.40) (2.21)

40    22

(2.40) (2.22)

Ignition: ON

10-14 V

11-14 V

Fault stored  12 (eliminate fault read out)

 7.1

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 7.1

Voltage supply

N30/1



40    7

(2.40) (2.7)

Ignition: ON

11-14 V

Cables

 1.0

ASR control unit (N30/1)

 7.2

 7.2

Coil resistance

N30/1



27    7

(2.27) (2.7)

Ignition: OFF

Disconnect N30/1 from

contact box

40-80 W

Cables

Solenoid valve relay (A7/3k1)

 7.3

 7.3

Working contact

N30/1



W14   1

(Figure 4) (2.1)

Ignition: OFF

Disconnect N30/1 from

contact box

<12 W

Cables

Solenoid valve relay (A7/3k1)

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 8.0 

High-pressure pump/return pump relay (A7/3k2)

Voltage supply

N30/1



40    7

(2.40) (2.7)

Ignition: ON

11-14 V

Cables

 8.1

 8.1

Coil resistance

N30/1



28    7

(2.28) (2.7)

Ignition: OFF

Disconnect control unit

(N30/1) from contact box

40-80 W

Cables

A7/3k2

 9.0 

Models 124.036 as of 02/93, 129.076, 140.04/05/07

Switch-over valve, master brake cylinder (Y61)

Internal resistance

N30/1



1    19

(2.1) (2.19)

Ignition: OFF

Disconnect control unit

(N30/1) from contact box

7-8 W

Cables

Y61

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 10.0 

Stop lamp switch ASD/ASR (S9/1)

NO contact

N30/1



40    49

(2.40) (1.8)

Ignition: ON

Do not operate brake

Operate brake

<1 V

11-14 V

Cables

S9/1

NC contact

N30/1



40    45

(2.40) (1.4)

Do not operate brake

Operate brake

11-14 V

<1 V

 11.0

Parking brake switch (S12)

N30/1



40    47

(2.40) (1.6)

Ignition: ON

Operate parking brake

Engine: Idling

Do not operate parking brake

Check parking brake (A1e7): ON

<1 V

A1e7: OFF

11-14 V

Cables

A1e7

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 12.0

Snow chain switch (ASR) (S76)

N30/1



40    55

(2.40) (1.14)

Engine: Idling

S76 in position: keep pressed ON

S76 in position: keep pressed OFF

<1 V

Function display in S76: OFF

11-14 V

S76: OFF

Cables

S76

ASR control unit (N30/1)

 13.0 



Models 124.036 as of 02/93, 129.076, 140.04/05/07

ASR lateral acceleration pickup (B24/2)

Voltage supply

Sensor signal off

Sensor signal, dynamic

N30/1



75    64

(1.34) (1.23)

N30/1



75    42

(1.34) (1.1)

N30/1



75    42

(1.34) (1.1)

Ignition: ON

Shake vehicle vigorously in transverse direction

4.75-5.25 V

2.35-2.65 V

>0.01 V 

Value changes with movement

Cables

B24/2

 13.1

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 13.1

Voltage supply to sensor input

N30/1



75    64

(1.34) (1.23)

Ignition: ON

Disconnect coupling on lateral acceleration sensor (B24/2)

4.75-5.25 V

Cables

ASR control unit (N30/1)

 14.0 





Left front wheel speed sensor (L6/1)

N30/1



10    30

(2.10) (2.30)

Raise front of vehicle

Ignition: ON

Turn left front wheel by hand

>0.1 V 

 14.1

 14.2

 14.1

Insulation resistance

N30/1



40    30

(2.40) (2.30)

Ignition: OFF

Disconnect ASR control unit (N30/1) from contact box

>20 kW

Cables

 14.2

Internal resistance

N30/1



10    30

(2.10) (2.30)

Ignition: OFF

Disconnect N30/1 from

contact box

0.8-3.7 kW

Cables

L6/1

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 15.0

Left front speed sensor output

N30/1



40    77

(2.40) (1.36)

Raise vehicle at front

Ignition: ON

Turn front left wheel by hand

>3 V 

Cables

 14.0

 15.1

ASR control unit (N30/1)

 15.1

Load by connected control units

N30/1



40    77

(2.40) (1.36)

Ignition: OFF

Disconnect N30/1 from

contact box

>5 kW

Cables

connected control units (if required N4/1, N4/3, N10/2, N22 or A2, A2/3y).

 16.0 





Right front wheel speed sensor (L6/2)

N30/1



13    34

(2.13) (2.34)

Raise vehicle at front

Ignition: ON

Turn front right wheel by hand

>0,1 V 

 16.1

 16.2

 16.1

Insulation resistance

N30/1



40    34

(2.40) (2.34)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

>20 kW

Cables

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 16.2

Internal resistance

N30/1



13    34

(2.13) (2.34)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

0.8-3.7 kW

Cables

L6/2

 17.0

Right front wheel speed sensor output

N30/1



40    79

(2.40) (1.38)

Raise vehicle at front

Ignition: ON

Turn front right wheel by hand

>3 V 

Cables

 16.0

 17.1

ASR control unit (N30/1)

 17.1

Load by connected control units

N30/1



40    79

(2.40) (1.38)

Ignition: OFF

Disconnect N30/1 from

contact box

>5 kW

Cables

connected control units (N16/1, N51, N30/2 if required).

 18.0 





Left rear wheel speed sensor (L6/3)

N30/1



73    74

(1.32) (1.33)

Raise vehicle at rear

Ignition: ON

Turn left rear wheel by hand

>0.1 V 

 18.1

 18.2

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 18.1

Insulation resistance

N30/1



40    74

(2.40) (1.33)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

>20 kW

Cables

 18.2

Internal resistance

N30/1



73    74

(1.32) (1.33)

Ignition: OFF

Disconnect N30/1 from

contact box

0.6-3.2 kW

Cables

L6/3

 19.0

Left rear wheel speed sensor

N30/1



40    69

(2.40) (1.28)

Raise vehicle at rear

Ignition: ON

Turn rear left wheel by hand

>3 V 

Cables

 18.0

 19.1

ASR control unit (N30/1)

 19.1

Load by connected control units

N30/1



40    69

(2.40) (1.28)

Ignition: OFF

Disconnect N30/1 from

contact box

>5 kW

Cables

connected control units (N4/3, N30/2, N49/1 if required).

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 20.0 





Right rear wheel speed sensor (L6/4)

N30/1



71    72

(1.30) (1.31)

Raise vehicle at rear

Ignition: ON

Turn rear right wheel by hand

>0.1 V 

 20.1

 20.2

 20.1

Insulation resistance

N30/1



40    72

(2.40) (1.31)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

>20 kW

Cables

 20.2

Internal resistance

N30/1



71    72

(1.30) (1.31)

Ignition: OFF

Disconnect ASR control unit (N30/1) from contact box

0.6-3.2 kW

Cables

L6/4

 21.0

Right rear wheel speed sensor output

N30/1



40    67

(2.40) (1.26)

Raise vehicle at rear

Ignition: ON

Turn right rear wheel by hand

>3 V 

 20.0

 21.1

ASR control unit (N30/1)

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 21.1

Loading by connected control units

N30/1



40    67

(2.40) (1.26)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

>5 kW

Cables

connected control units (N4/3, N30/2, N49/1 if required)

 22.0 





Pressure switch (A7/3s1)

N30/1



37    68

(2.37) (1.27)

Engine: Idling

Accumulator: Charged

Vent accumulator at connection "SP" for max. 2 s

9-14 V

<3 V

 22.1

 33  1.0 and 2.0

Accumulator not charged

Cables

ASR hydraulic unit (A7/3)

 22.1

Pressure switch

N30/1



W14   37

(Figure 4) (2.37)

Ignition: ON

Disconnect solenoid valve relay (A7/3k1)

Disconnect ASR control unit (N30/1) from contacting box

Accumulator: Charged

Accumulator: Vented

<1.8 kW

>20 kW

Cables
A7/3

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 23.0 

Solenoid valve front axle, left (A7/3y1)
Internal resistance

N30/1



20    21

(2.20) (2.21)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

0.7-2.2 W

Cables

ASR hydraulic unit (A7/3)

 24.0 

Solenoid valve front axle, right (A7/3y2)
Internal resistance

N30/1



39    21

(2.39) (2.21)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

0.7-2.2 W

Cables

ASR hydraulic unit (A7/3)

 25.0 

Solenoid valve rear axle, left (A7/3y3)
Internal resistance

N30/1



2    21

(2.2) (2.21)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

0.7-2.2 W

Cables

ASR hydraulic unit (A7/3)

 26.0 

Solenoid valve rear axle, right (A7/3y4)
Internal resistance

N30/1



24    21

(2.24) (2.21)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

0.7-2.2 W

Cables

ASR hydraulic unit (A7/3)

 27.0 

Switch-over solenoid valve (A7/3y5)
Internal resistance

N30/1



5    21

(2.5) (2.21)

Ignition: OFF

Disconnect ASR control unit

(N30/1) from contact box

1.8-3.0 W

Cables

ASR hydraulic unit (A7/3)

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 28.0 







CAN data line

N30/1

L    H

Ignition: OFF

Withdraw contacting module 2

or ABS/ASR control unit (N30/1). Check with ohmmeter directly at the two wide connections of the connector for the control unit (N30/1) (figure 17)

55-65 W

Data line

 28.1

 28.1

CAN module LH or HFM control unit (N3/1, N3/4)
Resistance

Engines 104, 119

N3/1

L    H

Withdraw N3/1 or N3/4 and

test directly at control unit (figure 14)

115-125 W

N3/1 or N3/4

 28.2

 28.2

CAN module in EZL/AKR control unit (N1/3, N1/4, N1/5)

Resistance

Engines 104 LH, 119 LH

N1/3

3    4

Engine 120

N1/4

N1/5

3    4

Disconnect connector "B" on

EZL/AKR control unit (N1/3) and test directly at the EZL control unit (figure 15)

Disconnect connector "B" on the left and right of the EZL/AKR control unit (N1/4 and N1/5) and test directly at the EZL/AKR control unit (figure 15)

115-125 W

N1/3

N1/4

N1/5

Test
step

Fault

code

Scope of test

Measuring equipment/
test connection

Operation/
requirement

Nominal value

Possible cause/remedy

 29.0

Model 140 with HFM or as of 06/93

Speed sensor output

Status

Signal: Vehicle stationary

N30/1



40    44

(2.40) (1.3)

Ignition ON

>3 V 

 29.1

 29.1

Signal: Fault

N30/1



40    44

(2.40) (1.3)

Ignition ON

<10 V

 14.0

ASR control unit (N30/1)