Code 28

CIRCUIT DESCRIPTION
The 2-3 solenoid is a simple ON/OFF solenoid located in the main case valve body. The solenoid is the normally open-type. In first or second gear, the TCM energizes the solenoid to close a fluid inlet port. When the port is open, fluid pressure actuates the shift valve.

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 43 of TCM connector.
3. The wire between terminal 43 of the TCM connector may be shorted to a supply wire to another solenoid at main case connector. Also, the wires between TCM terminals 43 and 54 and the main case connector may be open.
4. The wire between terminal 1 of the main case connector may be short to a supply wire to another solenoid at the main case connector.

DIAGNOSTIC AIDS
Trouble Code 28 sets when the TCM detects an open or short to voltage at terminal 43. In the event of an electrical failure, both the 1-2/3-4 and 2-3 shift solenoids are de-energized. The transmission will drive in fourth gear at D & 3 range. Lower ranges and reverse may be selected manually.

CIRCUIT DIAGRAM

2-3 Shift Solenoid Circuit:

CODE 28 DIAGNOSTIC CHART

Code 28 Diagnostic Chart: