Code 77/81 - Front Solenoid Circuit Shorted To Battery: Notes

Code 77 - Left Front Wheel
Code 81 - Right Front Wheel

This test identifies a solenoid that cannot be energized due to a short to battery in circuit between EBCM and solenoid. This condition will not allow blocking of brake fluid for that channel, making ABS operation for that wheel impossible.

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 77/81 Diagnostic Flow Chart

Courtesy of GENERAL MOTORS CORP.

Checks for internal short to battery in solenoid.
Checks solenoid coil resistance.
Checks for short to voltage in control circuit.
Checks for intermittent problem in solenoid circuit due to poor connector terminal contact.