Code 77

CIRCUIT DESCRIPTION
When the driver presses the accelerator pedal down fully, the kickdown switch closes, sending a ground signal to the TCM.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. This test determines if a problem exists with the TPS sensor.
2. This test determines if the wiring or the kickdown switch is shorted to ground.
3. This test isolates the short circuit.
4. This test checks the continuity of the wiring and the kickdown switch.

DIAGNOSTIC AIDS
Trouble Code 77 sets when the TCM detects a short to ground at terminal 15 when the throttle position is less than 70 percent for 1 second and kickdown function is disabled. If the fault is intermittent and does not continue for more than 3 seconds, the kickdown function is reestablished but the code remains.

CIRCUIT DIAGRAM

Kickdown Switch Circuit:

CODE 77 DIAGNOSTIC CHART

Code 77 Diagnostic Chart: