Range Selector Display Inoperative or Displays Incorrect Range

Range Selector Display Inoperative or Displays Incorrect Range





Test 1-6





Test 7-15





Test 16-20

Circuit Description
The Transmission Range (TR) switch is part of the park/neutral position and back-up lamp switch assembly and is externally mounted on the transmission manual shaft. The TR switch is a multi-signal switch. The PCM supplies ignition voltage to the TR switch on four signal circuits (A, B. C, and P). Each gear selector lever position grounds one or more of the switch circuits. In order to determine the gear range selected by the driver, the PCM compares the voltage combinations on the signal circuits to a look up table stored in the PCM memory.
The PCM detects the selected gear range by the state change of the switch input. Refer to Transmission Range Switch Logic. The switch input to the PCM is represented on the Scan Tool as HI and LOW. HI indicates an ignition voltage signal. LOW indicates a zero voltage signal. The four parameters represent transmission range switch signal A, B. C and Parity.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. If the Scan Tool display indicates the proper range positions in this step, a condition exists between the underhood accessory wiring junction block and the instrument cluster.
5. By disconnecting the transmission range switch, the ground path of all TR switch circuits would be removed and the PCM would recognize all circuits as open. The Scan Tool will display HI for all range signals.
6. This step tests the TR switch wiring for an open or the lack of the signal voltage from the PCM.
7. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the Scan Tool range signal A should change to LOW.
8. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the Scan Tool range signal B should change to LOW. If other circuits also indicate LOW, they are shorted together.