Code 15 - Abs Enable Relay Contacts Shorted To Battery Or Always Closed: Notes

Ignition voltage is supplied through ABS enable relay. EBCM/EBTCM energizes pull-in coil by completing ground circuit at EBCM/EBTCM ABS relay control terminal. Magnetic field created will close ABS enable relay contacts to supply battery voltage to EBCM/EBTCM, providing power to motors and solenoids.

Code 15 can only set before EBCM/EBTCM commands ABS enable relay on. This test determines if ABS enable relay is energized when it should not be. This malfunction would not allow ABS enable relay to remove power from ABS system. If second fault occurs that requires ABS enable relay to be turned off, that malfunction cannot be removed if relay cannot be controlled. Malfunction must be present for 3 consecutive drive cycles before a code will set. Code will be stored but, ABS is not disabled.

NOTE: Test numbers refer to numbers on diagnostic chart. Use only 10-megohm (minimum) DVOM for all voltage and resistance tests. For identification of circuits and terminals referenced in charts and text, see WIRING DIAGRAM .

Fig 1: Code 15 - Diagnostic Flow Chart

Courtesy of GENERAL MOTORS CORP.

Determines if any other code is present.
Determines if EBCM/EBTCM is capable of controlling ABS enable relay as commanded.
Checks for possible short to battery voltage in EBCM/EBTCM switched battery input terminal.
Determines if short to battery voltage is in EBCM/EBTCM switched battery input terminal or ABS enable relay.
Checks for intermittent in wiring or connectors.