Test S Main Relay Ground Test

S: Main Relay Ground Test:

ABS/TCS:

OPERATION:
^ When the ignition switch is first turned to RUN, 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 are 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 fault, 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 fuse 19), 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 light with no codes being set.

POSSIBLE CAUSES:
- Open in CKT 251, 852 or 1633.
- Open bulb.
- Short to voltage in CKT 852.
- Open or shorted antilock diode.
- Main relay fails "engaged."
- Short to ground in CKT 1632.