Code 34

CIRCUIT DESCRIPTION
The band apply solenoid is normally open solenoid which controls the flow of fluid for brake band application. The TCM uses Pulse Width Modulation (PWM) to control the solenoid. The TCM turns the solenoid on (energized) and off (de-energized) at a constant frequency. The length of time the solenoid is energized during each on/off cycle is called the pulse width. By varying or "modulating" the pulse width, the solenoid output pressure is changed. Since the solenoid is normally closed, increasing the pulse width increases the duty cycle and decreases the output pressure. Decreasing the pulse width decreases the duty cycle and increases the output pressure. PWM control provides smooth band application without an accumulator. The band is only applied in first and second gears.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. This test checks the continuity of the solenoid windings and wires to the solenoid.
2. This test checks for a short to voltage at terminal 45 of the TCM connector.
3. This wire from terminal 45 of the TCM connector may be shorted to a supply wire of another solenoid at the main case connector. Also, the wire between terminal 54 and the main case may be open.
4. The wire at terminal 2(B) of the main case connector may be shorted to a supply wire of another solenoid. Also, the wire between terminal 4(C) of the main case and the solenoid may be open.

DIAGNOSTIC AIDS
Trouble Code 34 sets when the TCM detects an open or a short to battery voltage at terminal 45. In the event of an electrical failure, the solenoid regulates at the maximum oil flow (0% duty cycle).

CIRCUIT DIAGRAM

Band Apply Solenoid Circuit:

CODE 34 DIAGNOSTIC CHART

Code 34 Diagnostic Chart: