DTC 18

DTC 18 ABS Enable Relay Coil Circuit Shorted To Battery:

Circuit Description:
Ignition voltage is supplied through terminal "C1O" of the ABS enable relay. The EBCM then is able to energize the pull-in coil by completing the ground circuit at terminal "D3" of the EBCM. The magnetic field created closes the ABS enable relay contacts and allows battery voltage and current to be supplied to the EBCM, which supplies voltage 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 and solenoids. A malfunction of this type will not allow voltage to be available to the motors and solenoids; therefore, ABS operation would not be allowed if required.

Action Taken:
A malfunction DTC is stored, ABS 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 that the EBCM is capable of controlling the ABS enable relay as commanded
2. Checks for a short to voltage on the relay control circuit.
3. Verifies that the relay coil has the appropriate resistance.
4. Verifies that the relay contacts are not failed closed.
5. Checks for possible poor terminal contact at the EBCM.

Diagnostic Aids:
An "Intermittent" malfunction may be 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.