Test step
Impulse readout |
Scope of test |
Test equipment/
test connection
|
Test condition |
Nominal value |
Possible cause/remedy |
 1.0 1 |
Entire system |
|
|
|
|
|
No malfunctions in memory.
|
| 2.0 2 |
Roll bar control unit (N53) |
|
|
|
Ignition: ON |
Impulse readout
2 erased |
Replace N53 ,
(91-840).
|
| 3.0 3 |
Voltage supply
Circuit 30 |
2 
|
N53
 |
 10
|
Ignition: OFF
Disconnect plug at the roll bar control unit (N53). Connect test cable and socket box according to the connection diagram.
|
11-14 V |
Battery,
Fuse 4, circuit 30 (F20-4) defective.
Open circuit.
Alternator voltage regulator defective. |
| 3.1 3 |
Circuit 15 |
9
|
N53
|
11
|
Ignition: ON |
11-14 V |
Open circuit,
Connector, interior/taillamp harness (8-pole) (X18/3) disconnected.
Fuse 8, circuit 15 (F1-8) defective.
Ignition/start switch defective.
|
| 4.0 4 |
Driver seat belt lock relay
(K18/2) with wiring |
4
|
N53 X55 /3
|
1
|
Ignition: OFF
Disconnect plug at the roll bar control unit (N53), connect socket box. Separate left seat contact strip (X55/3).
|
< 1  |
N53,
Open circuit,
|
|
|
W18
|
X55 /3
|
2 |
|
> 11 V |
Open circuit
Fuse 4, circuit 30
(F20-4) defective.
|
|
|
(B1)
1 
|
X55 /3
|
(B1)
 2
|
|
60-90 |
Connector at K18/2 unplugged.
Replace driver's seat belt unit (91-502). |
| 4.1 4 |
Isolation from ground
|
(B1)
|
X55 /3
|
W18
1 |
Separate left seat contact strip (X55/3, B1). |
> 20 k |
Short to circuit 31 |
| 4.2 4 |
Isolation from ground |
(B1)
|
X55 /3
|
W18
2 |
Separate left seat contact strip (X55/3, B1). |
> 20 k |
Short to circuit 31 |
| 4.3 4 |
Isolation from ground
|
(B1)
1 |
X55 /3
|
(B1)
2 |
Ignition: OFF
Disconnect battery negative cable and cover pole.
Separate left seat contact strip
(X55/3, B1). |
> 20 k |
Short to circuit 15, 30 |
| 4.4 4 |
Isolation from ground |
(B1)
2 |
X55 /3
|
(B1)
2 |
Ignition: OFF
Disconnect battery negative cable and cover pole.
Separate left seat contact strip
(X55/3, B1). |
> 20 k |
Short to circuit 15, 30 |
| 4.5 4 |
Isolation from ground |
|
N53
|
4
|
Ignition: OFF
Disconnect battery negative cable and cover pole, socket box connected to roll bar control unit (N53) connector |
> 20 k |
Short to circuit 31 |
|
|
4
|
N53
|
10
|
|
> 20 k |
Short to circuit 15, 30 |
| 4.6 4 |
Testing left seat belt latch and seat belt lock relay (K18/2) |
|
|
|
Ignition: OFF
Disconnect battery ground cable,
Seat belts latched. |
Seat belt reel is locked
|
Seat belt automatic reel defective, Bowden cable defective |
|
|
|
|
|
Seat belts not latched. |
Seat belt moves freely |
Bowden cable defective and/or not connected at the seat belt latch. |
|
|
|
|
|
Loosen seat belts again
Connect the battery ground cable.
Seat belts latched.
|
Seat belt continues to move freely |
Driver seat belt lock relay (K18/2) defective
and/or open circuit |
| 5.0 5 |
Passenger seat belt lock relay
(K18/3) with wiring |
|
|
|
Ignition: OFF
Disconnect plug at roll bar control unit (N53) Connect socket box. Separate right seat contact strip (X55/4). |
|
|
|
|
3
|
N53 X55 /4
|
10
|
|
< 1 |
N53 open circuit.
|
| [5.0] 5 |
Front passenger seat belt lock relay (K18/3), with wiring |
W19
|
X55 /4
|
2 |
|
> 11 V |
Open circuit.
Fuse 4, circuit 30 (F20-4) defective. |
|
|
(B1)
1 |
X55 /4
|
(B1)
2 |
|
60-90 |
Connector unplugged at passenger seat belt lock relay (K18/3).
Replace seat belt tensioner unit (91-502). |
| 5.1 5 |
Isolation from ground
|
(B1)
|
X55 /4
|
W19
1 |
Right seat contact strip (X55/4, B1) separated. |
> 20 k |
Short to circuit 31 |
| 5.2 5 |
Isolation from ground
|
(B1)
|
X55 /4
|
W19
2 |
Right seat contact strip (X55/4, B1) separated. |
> 20 k |
Short to circuit 31 |
| 5.3 5 |
Isolation from ground
|
(B1)
1 |
X55 /4
|
(B1)
2 |
Ignition: OFF
Disconnect negative battery cable
Right seat contact strip (X55/4, B1) separated.
|
> 20 k |
Short to circuit 15, 30 |
| 5.4 5 |
|
(B1)
2 |
X55 /4
|
(B1)
2 |
Ignition: OFF
Disconnect negative battery cable
Right seat contact strip (X55/4, B1) separated. |
> 20 k |
Short to circuit 15, 30 |
| 5.5 5 |
Wiring |
|
N53
|
3
|
Ignition: OFF,
Disconnect negative battery cable and cover pole.
Socket box connected to roll bar control unit (N53) connector.
|
> 20 k |
Short to circuit 31 |
|
|
3
|
N53
|
10
|
|
> 20 k |
Short to circuit 15, 30 |
| 5.6 5 |
Right seat belt latch and seat belt lock relay (K18/3) |
|
|
|
Ignition: OFF
Disconnect battery ground cable.
Seat belt latched.
|
Seat belt automatic reel is locked |
Seat belt automatic reel defective, Bowden cable defective. |
|
|
|
|
|
Seat belt not latched.
|
Seat belt moves freely |
Bowden cable defective and/or not connected at the seat belt latch. |
|
|
|
|
|
Loosen seat belt again.
Connect the battery ground cable. Seat belt latched.
|
Seat belt continues to move freely |
Front passenger seat belt lock relay (K18/3) defective and/or open circuit. |
| 6.0 6 |
Roll bar deployment solenoid (Y57/1)
with wiring |
1
|
N53
|
10
|
Ignition: OFF
Disconnect plug at the roll bar control unit (N53). Connect test cable and socket box according to the connection diagram. Remove fuse 4, circuit 30 (F20/4).
|
0.5-1.5 |
Right deployment and retraction component defective.
Connector, roll bar solenoid valve (X23) unplugged.
Connector at Y57/1 unplugged.
Open circuit, short: open circuit. |
|
|
1 |
X23
|
2 |
Roll bar solenoid connector,
2-pole (X23), unplugged. |
0.5-1.5 |
Connector at Y57/1 unplugged.
Right deployment and retraction component defective. |
| 6.1 6 |
Insulation resistance
|
W19
|
X23
|
2 |
Ignition: OFF
Remove fuse 4, terminal 30 (F20/4) |
> 20 k |
Short to circuit 31 |
|
|
W19
|
X23
|
1 |
|
> 20 k |
Short to circuit 31 |
|
|
1 |
X23
|
2 |
|
> 20 k |
Short to circuit 15, 30 |
| 6.2 6 |
Insulation resistance
|
2 |
X23
|
2 |
Ignition: OFF
Remove fuse 4, terminal 30 (F20/4) |
> 20 k |
Short to circuit 15, 30 |
| 7.0 7 |
Left rear axle switch, roll bar (S83/2)
Right rear axle switch, roll bar (S83/3) |
15 |
N53
|
16
|
Ignition: OFF
Unplug connector at roll bar control unit (N53), remove fuse.
Connect test cable and socket box according to connection diagram.
|
< 1 |
> 1 open circuit.or connector rear axle multiple circuit junction (X62/8) (C) unplugged.
Connector at S83/2 and/or S83/3 unplugged.
S83/2 and/or S83/3 defective (91-860).
|
| 7.1 7 |
Isolation from ground
|
9
|
N53
|
15
|
|
> 20 k |
Short to circuit 31,
Open circuit.
Open circuit to left rear axle roll bar switch (S83/2).
|
| 7.2 7 |
Isolation from ground
|
9
|
N53
|
16
|
|
> 20 k |
Short to circuit 31,
Open circuit. to right rear axle roll bar switch (S83/3). |
| 7.3 7 |
Circuit isolation |
15
|
N53
|
10
|
Ignition: OFF
Unplug connector at roll bar control unit (N53), remove circuit fuse.
Connect test cable and socket box according to connection diagram.
|
> 20 k |
Short to circuit 15, 30,
Open circuit to right rear axle roll bar switch (S83/3). |
| 7.4 7 |
Circuit isolation
|
16
|
N53
|
10
|
|
> 20 k |
Short to circuit 15, 30,
Open circuit to left rear axle roll bar switch (S83/2).
|
| 7.5 7 |
Left rear axle roll bar switch (S83/2) and right rear axle roll bar switch (S83/3) for function. |
|
|
|
Connector at roll bar control unit (N53) connected.
Turn S83/2 or S83/3 to "Arretiert"
|
When the brakes are abruptly applied above approx. 10 km/h (6 mph), the roll bar deploys. |
If the roll bar does not deploy, read out the malfunction codes from the malfunction memory. test roll bar switches (S83/2, S83/3) and switch adjustment. |
|
The roll bar must deploy. |
|
|
|
The vehicle must be driven for the test (91-830).
|
Warning lamp comes on. |
|
| 8.0 8 |
Roll bar warning lamp (A1e29)
|
|
|
|
Ignition: ON |
Warning lamp comes on. |
Warning lamp connector, interior/taillamp harness (X18/3) unplugged.
Open circuit.
|
| 8.1 8 |
Wiring for open circuit |
X18 /3
7 |
N53
|
6 |
Ignition: OFF
Unplug connector at roll bar control unit (N53). Connect test cable and socket box according to the connection diagram.
|
< 1 |
Open circuit |
| 8.2 8 |
Isolation from ground
|
9
|
N53
|
7
|
Socket box connected.
Separate connector, interior/taillamp harness 8-pole (X18/3).
|
> 20 k |
Short to circuit 31.
Open circuit. |
| 8.3 8 |
Isolation from ground
|
7
|
N53
|
10
|
Ignition: OFF
Remove fuse 4 from circuit 30 (F20/4) |
> 20 k |
Short to circuit 15, 30.
Open circuit.
|
Printable version
