GM Service Manual Online
For 1990-2009 cars only
Table 1: Transmission Range Switch Valid Combination Table

DTC Description

This diagnostic procedure covers the following DTCs:

    • DTC P0705--Transmission Range Sensor Circuit Range/Performance.
    • DTC P0706--Transmission Range Sensor Circuit.

Circuit Description

The transmission range (TR) switch is part of the Transmission Park/Neutral Position switch mounted on the transmission manual shaft. The four inputs from the transmission range switch indicate to the powertrain control module (PCM) which position is selected by the transmission selector lever. The input voltage level at the PCM is high (B+) when the transmission range switch is Open, and low when the switch is Closed to ground. The state of each input is available for display on Tech 2. The four parameters on Tech 2 represent transmission range switch A, B, C, and P (Parity) inputs respectively. Valid transmission input combinations are shown in the Transmission Range Switch Valid Combination table.

When the PCM detects an invalid transmission range input combination, a TR sensor DTC will set.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    • The Transmission Range switch inputs indicate an invalid combination.
    • The above condition is present for longer than 30 seconds.

Conditions for Clearing the DTC

The Transmission Range switch DTCs are Type C DTCs. Refer to Diagnostic Starting Point - Automatic Transmission for Action Taken when Type C DTCs set and Conditions for Clearing Type C DTCs.

Additional Information

    • Refer to Symptoms - Automatic Transmission for details of the TFT sensor operation.
    • For an intermittent fault condition, refer to Intermittent Conditions.
    • Since a fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic procedure for shorted terminals or poor wiring connection before replacing any component. Refer to Testing for Intermittent Conditions and Poor Connections for information on electrical fault diagnosis.
    • Refer to Automatic Transmission Controls Schematics , Automatic Transmission Inline 20-Way Connector End View , Automatic Transmission Internal Connector End Views , Automatic Transmission Control Module Connector End Views , and Automatic Transmission Related Connector End Views to aid in the diagnosis procedures.

Transmission Range Switch Valid Combination Table

Gear Selector Position

Tech 2 TR Switch P/A/B/C Display

P

A

B

C

Park (P)

Closed 0 V

Closed 0 V

Open 12 V

Open 12 V

Reverse (R)

Open 12 V

Closed 0 V

Closed 0 V

Open 12 V

Neutral (N)

Closed 0 V

Open 12 V

Closed 0 V

Open 12 V

D

Open 12 V

Open 12 V

Closed 0 V

Closed 0 V

3

Closed 0 V

Closed 0 V

Closed 0 V

Closed 0 V

2

Open 12 V

Closed 0 V

Open 12 V

Closed 0 V

1

Closed 0 V

Open 12 V

Open 12 V

Closed 0 V

Test Description

The following numbers refer to the step numbers in the diagnostic chart.

4 Disconnecting the transmission range switch connector should cause the PCM to interpret all the circuits as open, and the TR switch display on Tech 2 should indicate Open 12 V for all four switches. This would indicate that the circuits from the TR switch and the PCM are all serviceable.

5 If all the TR switch displays on Tech 2 are Open 12 V, the fault could be in the TR switch ground circuit.

7 By providing the ground for each transmission range switch circuit, the PCM should respond by changing the TR switch display from Open 12 V to Closed 0 V. For the circuits that do not change, an open circuit may exist.

Step

Action

Yes

No

1

Was the Main Diagnostic Table performed?

Go to Step 2

Refer to Diagnostic System Check - Automatic Transmission

2

  1. Observe the Freeze Frame/Failure Record for this DTC.
  2. Switch OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running the DTC or within the conditions in the Freeze Frame/Failure Records.
  4. Using Tech 2, select Engine/Diagnostic Trouble Codes/Read DTC Information.

Does DTC P0705 or P0706 fail this ignition cycle?

Go to Step 3

Refer to Diagnostic Aids for the Transmission Range Sensor DTCs

3

  1. Switch the ignition ON with the engine not running.
  2. Using Tech 2, select Transmission/Data Display/Transmission Data and scroll down to TR Switch P (Transmission Range), TR Switch A (Transmission Range), TR Switch B (Transmission Range), TR Switch C (Transmission Range).
  3. Observe the TR Switch displays while selecting each gear position.
  4. Compare the display at each gear position selected to the Transmission Range Switch Valid Combination table.

Does the Tech 2 display match the Transmission Range Switch Valid Combinations table for each gear position?

Refer to Diagnostic Aids for the Transmission Range Sensor DTCs

Go to Step 4

4

  1. Switch the ignition OFF.
  2. Disconnect connector S187- X1 from the Transmission Park/Neutral Position switch.
  3. Switch the ignition ON with the engine not running.
  4. Using Tech 2, select Transmission/Data Display/Transmission Data and scroll down to TR Switch P (Transmission Range), TR Switch A (Transmission Range), TR Switch B (Transmission Range), TR Switch C (Transmission Range).

Is TR Switch P (Transmission Range): Open 12 V, TR Switch A (Transmission Range): Open 12 V, TR Switch B (Transmission Range): Open 12 V, TR Switch C (Transmission Range): Open 12 V displayed on Tech 2?

Go to Step 5

Go to Step 9

5

Reconnect connector S187-X1 to the Transmission Park/Neutral Position switch.

Is TR Switch P (Transmission Range): Open 12 V, TR Switch A (Transmission Range): Open 12 V, TR Switch B (Transmission Range): Open 12 V, TR Switch C (Transmission Range): Open 12 V displayed on Tech 2?

Go to Step 6

Go to Step 7

6

Test the TR switch ground circuit for a high resistance, open circuit, or short to voltage fault condition. Refer to Testing for Intermittent Conditions and Poor Connections for information on electrical fault diagnosis.

Was any fault found and rectified?

Go to Step 12

Go to Step 10

7

  1. Switch the ignition OFF.
  2. Disconnect connector S187-X1 from the Transmission Park/Neutral Position switch.
  3. Connect a 3-amp fused jumper wire between each TR switch signal circuit, one at a time, and a known ground.
  4. Switch the ignition ON with the engine not running.
  5. Using Tech 2, select Transmission/Data Display/Transmission Data and scroll down to TR Switch P (Transmission Range), TR Switch A (Transmission Range), TR Switch B (Transmission Range), TR Switch C (Transmission Range).

Does each TR Switch display on Tech 2 change from Open 12 V to Closed 0 V when the respective circuit is grounded?

Go to Step 10

Go to Step 8

8

Test each TR switch signal circuit (s) that did not change status for a high resistance, open circuit, short to ground, or short to voltage fault condition.

Was any fault found and rectified?

Go to Step 12

Go to Step 11

9

Test each TR switch signal circuit(s) that Tech 2 did not indicate as Closed 12 V for a short ground fault condition.

Was any fault found and rectified?

Go to Step 12

Go to Step 11

10

Replace the transmission Park/Neutral position switch. Refer to Park/Neutral Position and Backup Lamp Switch Replacement.

Was the repair completed?

Go to Step 12

--

11

Replace the PCM. Refer to Powertrain Control Module Replacement.

Was the repair completed?

Go to Step 12

--

12

  1. Using Tech 2, clear the DTCs.
  2. Switch OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC or within the conditions in the Freeze Frame/Failure Records.

Do any transmission range sensor circuit DTCs fail this ignition cycle?

Go to Step 2

Go to Step 13

13

Using Tech 2, select the DTC Display function.

Are there any DTCs display?

Go to the appropriate DTC Table

System OK

When all diagnosis and repairs are completed, check the powertrain management system for correct operation.