300TE 4MATIC (124.290) L6-3.0L (103.985) (1991)
Electronic Brake Control Module: Description and Operation
There are four different versions of the ABS/ASR control unit. This reflects the different performance maps for the electronic accelerator system.
There are two versions with speed sensor output and two without. This model uses on of the units without speed signal output.
Control Unit Connector
To prevent mistaken interchange of the different ABS/ASR control units for the different vehicle/engine combinations, there are two lugs cast on the
sides of the control unit connector; and at the front clasp there is a notch, located in different positions for the different vehicle/engine combinations.
Control Unit Connector
On the ABS/ASR control unit there are two notches (arrows) cast on the sides of the connector guide. In the catch on the right side there is a web (arrow)
in different positions depending on the vehicle/engine combination. The control unit consists of separate printed circuits equipped with electronic
components. The connection with the wiring harness uses a 35-pole connector.
Besides the ABS functions, the ABS/ASR control unit contains all the ASR functions. it is functionally divided as follows:
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Signal conditioning,
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Input amplifiers,
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Logic components,
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Safety circuits,
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Output drivers.
SIGNAL CONDITIONING
The signal conditioning components convert the input signals from the four wheel speed sensors (from the original sine-wave AC to a digital square
wave) and send them for processing to the ASR and ABS microcomputers.
INPUT AMPLIFIERS
There is an input amplifier for each of the inputs from the:
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Stop lamp switch,
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Throttle valve actual position signal,
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Snow chain switch,
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Pressure switch.