DTC 18

DTC 18 ABS Enable Relay Coil Circuit Shorted To Battery Or Coil Shorted:

Circuit Description:
Ignition voltage is supplied through terminal "86" of the ABS enable relay. The EBCM is then able to energize the pull-in coil by completing the ground circuit at EBCM terminal "22" (ABS w/o VES) or "20" (ABS w/VES). The magnetic field created closes the enable relay contacts and allows battery voltage and current to be supplied to the EMB's, EVO actuator (ABS w/VES), and EBCM, which supplies power to the motors and solenoids.

DTC Will Set When:
DTC 18 can be set after the EBCM commands the enable relay "ON." This test monitors the availability of current/voltage to the motors, solenoids and EMB's. A malfunction of this type will not allow voltage to be available to the motors, solenoids and EMB's; therefore, ABS operation would not be allowed if required.

Action Taken:
A malfunction DTC is stored, ABS/VES is disabled and the ABS warning lamp is turned "ON."

DTC Chart Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Indicates if the EBCM is capable of controlling the enable relay as commanded.
2. With the enable relay removed, voltage should not be available at terminal "85". Any voltage at this point would indicate that the enable relay control circuit was shorted to a voltage source.
3. Checks for a short across the ABS enable relay coil.
4. Checks for an internal short in the ABS enable relay between the B+ feed at terminal "30" and the relay pull-in coil.
5. Ensures short to B+ was not due to physical damage of the enable relay control circuit.

Diagnostic Aids:
An "Intermittent" malfunction is most likely caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

The frequency of the malfunction can be checked by using the enhanced diagnostic function of the Tech 1.

Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.