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Signal too large:
· The
wheel speed information at the affected wheel speed sensor input is higher
than 280 km/h (174 mph)
· Above
condition must be fulfilled for at least 1 s
or
Signal to ground, input open,
missing signal:
· Brake
pedal not actuated
· TC
system switched on
· At
least 4 s elapsed since ignition ON
· Vehicle
speed higher than 10 km/h (6 mph) (wheel speed information from one
intact signal)
· The
wheel speed signal from the affected wheel speed sensor input is 0, while the
wheel speed signal from at least one of the other wheel speed sensor inputs
is greater than 10 km/h (6 mph)
· Above
conditions must be fulfilled for at least 20 s
Note:
The control unit also recognizes
faults when the vehicle is being driven under extreme conditions similar to
those described above (e. g. driving off on a slope).
Faults are recognized at 1, 2
and 3 wheel speed inputs, for both simultaneous and sequential malfunctions.
For Model
Year '92 control units (C 20 XE engine with Motronic
M 2.5), simultaneous malfunction of all 4 wheel speed signals is not
recognized.
For control units as of Model
Year '93, the malfunction of all 4 wheel speed signals is recognized
using a plausibility check. For this, the brake / accelerator pedal
positions, the engine speed and the engine torque are evaluated. The fault
"malfunction of all four wheel speed signals" must exist for at
least 20 s.
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