ABS Indicator Inoperative W/No DTC Set

CIRCUIT DESCRIPTION
When the ignition switch is first turned to the RUN position, the EBCM/EBTCM goes through a self-test lasting 2-4 seconds. During this test, the EBCM/EBTCM grounds terminal 52, causing the amber ANTILOCK indicator to light. This serves as an indicator bulb test. The EBCM/EBTCM also grounds terminal 34, energizing the main relay. This removes the indicator ground path provided through the antilock diode and the main relay contacts.

When the self-test is completed (and no faults detected) the EBCM/EBTCM removes the ground at terminal 52, turning OFF the indicator. The main relay remains energized.

When the EBCM/EBTCM detects a malfunction, it grounds terminal 52 causing the amber ANTILOCK indicator to light. (Note: The EBCM/EBTCM also de-energizes the main relay creating a redundant ground path.)

When the EBCM/EBTCM is disabled for any reason (i.e., open ABS fuse), the main relay is de-energized. This provides an ANTILOCK indicator ground path through the antilock diode and main relay contacts, and causes the indicator to come ON with no DTC being set.

DIAGNOSTIC AIDS
Possible causes:
^ An open in CKT 1451, CKT 852, CKT 39, CKT 351, or CKT 1633.
^ An open CHIME fuse.
^ An open bulb.
^ A short to voltage in CKT 852.
^ An open or shorted antilock diode.
^ The ABS main relay fails engaged.
^ A short to ground in CKT 39, CKT 852, or CKT 1632.
^ A poorly seated EBCM/EBTCM connector.
^ A poor terminal contact at the EBCM/EBTCM connector terminal 52.

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ABS INDICATOR INOPERATIVE WITH NO DTC SET