Saturn Coupes/Sedans/Wagons 1991-1998 Repair Guide

Troubleshooting the ABS System


See Figures 1, 2 and 3

The Saturn ABS Electronic Brake Control Module (EBCM) is similar in many ways to the PCM described in Emission Controls of this repair guide. It is an electronic controller of the ABS system which is capable of monitoring system function through the system circuits. It will constantly monitor the output from its various sensors to determine if a sensor or circuit is operating properly.

When the EBCM detects a problem, it will set a trouble code or flag. If the fault is serious enough to affect braking, the EBCM will illuminate the red ANTILOCK warning lamp. Whenever the lamp is lit, the ABS system is disabled and will NOT operate, but normal hydraulic braking will exist. In this way, the system is prevented from ever disabling or adversely affecting the vehicle' hydraulic brakes due to a partial or complete ABS failure.

As with the PCM system, trouble codes and flags are stored in both general information and malfunction history circuits of the control module. General information is cleared each time the ignition switch is turned OFF , but codes will reset when the ignition is turned ON again and the malfunction is still present. Data will remain in malfunction history for a series of 100 ignition cycles after a fault disappears, unless a scan tool is used to clear the memory earlier. Disconnecting the power will have no affect on data stored in the EBCM malfunction history circuits.

Unlike the PCM system, on which a jumper wire can activate a flash code readout, a scan tool MUST be used for fault code diagnosis and troubleshooting on the ABS EBCM. The scan tool is connected to the system through the Assembly Line Data Link (ALDL) connector which is under the dashboard, near the driver' door.

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Fig. Fig. 1: ABS electrical schematic

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Fig. Fig. 2: EBCM pinout-1991-95 models

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Fig. Fig. 3: ABS control module pinout-1996-98 models


See Figures 4 and 5

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Fig. Fig. 4: ABS diagnostic trouble codes-1991-95 models

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Fig. Fig. 5: ABS diagnostic trouble codes-1996-98 models