Antilock Braking System (ABS)

DTC 14 ABS Enable Relay Contact Circuit Open:

CIRCUIT DESCRIPTION
Ignition voltage is supplied through terminal "85" of the ABS enable relay. The EBCM then is able to energize the pull-in coil by completing the ground circuit at terminal "A11" 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 power to the motors and solenoids.

DTC WILL SET WHEN
DTC 14 can be set anytime after the EBCM commands the ABS enable relay "ON" (the relay is first commanded "ON" during the three second bulb check). This test monitors the availability of current/voltage to the motors and solenoids. This malfunction indicates voltage is not available and would therefore not allow ABS operation 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. Checks to see if DTC 16 is also set as current or history. If DTC 16 is also set, proceed to that chart first.
2. Verifies that the malfunction is currently present.
3. Verifies that the relay can be turned "ON" and provide voltage to the EBCM.
4. Checks for high resistance in the switched battery circuit from the relay to the EBCM.
5. Checks for high resistance in the switched battery circuit from the battery to the relay.
6. Verifies the condition of the ABS enable relay.
7. Checks for poor terminal contact or corrosion at the connectors.
8. Determines if the EBCM is the cause of the malfunction.
9. Checks for high resistance in the entire relay coil circuit.
10. Verifies proper battery condition.
11. Verifies proper voltage is available at the ABS enable relay.
12. Checks for an open in the switched battery circuit from the relay to the EBCM.
13. Verifies the condition of the ABS enable relay.
14. Checks for proper resistance of the relay coil.
15. Checks for high resistance in the ABS enable relay control circuit between the relay and the EBCM.
16. Checks for high resistance in the ABS enable relay control circuit between the battery and the relay.

DIAGNOSTIC AIDS
An "Intermittent" problem may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

The frequency of the problem 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.

VIBRATION, TEMPERATURE EFFECTS
Check for vibration effects by performing the relay test function of the Tech 1. With the relay test commanded "ON," lightly tap the top and sides of the relay while monitoring relay voltage. If the relay voltage changes significantly, replace the relay.

If DTC 14 only sets when the vehicle is initially started in cold ambient conditions (temperature less than 32°F-0°C), replace the relay.