DTC 78

ABS Schematic: Code 78:

SOLENOID CIRCUIT 1289 OPEN OR GROUNDED
The two solenoids in the system control the normally open front hydraulic bypass valves. During an ABS stop, ground is supplied to close the valves and isolate brake pedal input. The low side of each solenoid is controlled by the ABS control module. The high side of each solenoid is connected to B+. A failure in the solenoid circuitry will turn On the antilock telltale.

CODE PARAMETERS
Code 78 sets if:
^ Solenoid circuit 1289 is open or grounded.
^ This code will fail at all times except when a previous failure has disabled ABS operation.
^ If the conditions for failure occur during initialization it may also fail code 15.

Diagnostic Chart: Code 78:

DIAGNOSTIC AIDS
If code 78 is set, switch the solenoid connectors and clear the code. If code 78 sets again, the problem is in the wiring or the ABS control module. If code 76 sets, the problem is in the solenoid.

Check circuit 1289 and the solenoid for an open. The resistance through the solenoid should be about 3.5 ohms.

When Attempting To Diagnose - an intermittent problem, use the scan tool to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem.

Intermittents Or Opens - suspected to be at the connectors can be detected by using a diagnostic service probe. Voltage can be read on wires without disconnecting any connectors.

Check the tightness of the female terminal grip with a spare male terminal.