GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC K Sierra - 4WD (CNG) 🢒 DTC 🢒 DTC P0705
Table 1: Transmission Range Switch Valid Input Combinations

Circuit Description

The transmission on this vehicle has a park neutral position (PNP) and back-up switch. This switch incorporates a transmission range selector switch. There are 4 inputs, PRND A, B, C, P, which are switches to ground. The 4 switches have an unique switch pattern. The powertrain control module (PCM) and the Alternative Fuels ECM use the combination of the switch patterns in order to determine the gear selected by the driver.

This diagnostic monitors the 4 inputs in order to determine what gear position the transmission is in. When the Alternative Fuels ECM detects that an illegal range has occurred, this DTC sets.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC
    • The transmission range select lever switch indicates an illegal position.
    • The Alternative Fuels ECM detects an illegal range for 30 seconds.

Action Taken When the DTC Sets
    • The Alternative Fuels ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The Alternative Fuels ECM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the Alternative Fuels ECM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the Alternative Fuels ECM records the operating conditions at the time of the failure. The Alternative Fuels ECM writes the conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    • The Last Test Failed status will clear when the DTC runs and passes.
    • The Alternative Fuels ECM will turn OFF the MIL after 3 consecutive drive trips that the DTC runs and passes.
    • The History status will clear after 40 consecutive WARM-UP cycles with NO failures of ANY DTC.
    • All DTC Information can be cleared with a scan tool.

Diagnostic Aids

This DTC will set if the gear shift cable, or PNP switch is not adjusted properly. Also, if the gear shift lever is held between gears, this DTC will set.

Refer to Range Selector Lever Cable Adjustment and Park/Neutral Position Switch Adjustment in Automatic Transmission-4L80-E in the C/K Pickup Service Manual.

The table below is the normal state that each gear range should indicate. LOW indicates the circuit is low, switched or shorted to a ground. HI indicates the circuit is high or open. Another parameter to display is the TR Sw. A/B/C/P range. This parameter displays the current gear range the transmission is in. When there is an invalid gear range, the parameter indicates Invalid.

Transmission Range Switch Valid Input Combinations

Gear Selector Position

Scan Tool Trans Range ABCP Display

A

B

C

P

Park (P)

LOW

HI

HI

LOW

Reverse (R)

LOW

LOW

HI

HI

Neutral (N)

HI

LOW

HI

LOW

Drive 4 (OD)

HI

LOW

LOW

HI

Drive 3 (3)

LOW

LOW

LOW

LOW

Drive 2 (2)

LOW

HI

LOW

HI

Drive 1 (1)

HI

HI

LOW

LOW

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if the condition is present.

    2.

  2. This step determines if the condition affects the PCM. If the Transmission Data display matches the selected transmission range, the condition only affects the Alternative Fuels ECM.

    3.

  3. This step determines if the ground circuit of the TR switch is the cause of the condition. If the data displays HI for all of the circuits, test the ground circuit for an open.

    4.

  4. When the TR switch is disconnected, all of the data parameters should display HI.

  5. This step tests TR switch wiring for an open or the lack of the signal voltage from the PCM.

    6.

  6. This step tests TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal should change to LOW.

    7.

  7. This step tests for an open circuit between the Alternative Fuels ECM and the splice.

  8. This step determines if the Alternative Fuels ECM is the cause of the condition. If the data display switches from LOW to HI when the Alternative Fuels ECM is disconnected, the module is causing the short to ground.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check Alternative Fuels - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Alternative Fuels (Engine Controls)

2

Important: Verify that the shift lever cable and the PNP switch are properly adjusted before proceeding with this diagnostic. Refer to Range Selector Lever Cable Adjustment and Park/Neutral Position Switch Adjustment in Automatic Transmission-4L80-E in the C/K Pickup Service Manual.

  1. Apply the parking brake.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, establish communication with the Alternative Fuels ECM.
  4. Observe the TR Sw. display while selecting each transmission range: P, R, N, D, 3, 2, and 1.

Does the TR Sw. parameter display an error in any range?

--

Go to Step 4

Go to Step 3

3
  1. Observe the Freeze Frame and/or Failure records data for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or as close to the Freeze Frame and/or Failure records data that you observed.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. With a scan tool, observe the Transmission Data Display.
  2. Observe the TR Sw. display while selecting each transmission range: P, R, N, D, 3, 2, and 1.

Does each selected transmission range match the scan tool TR Sw. display?

--

Go to Step 9

Go to Step 5

5

With the scan tool, observe the TR Sw. A/B/C/P display.

Does the TR Sw. A/B/C/P parameter indicate HI for all range signal states?

--

Go to Step 14

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Disconnect the TR switch connector C1. Refer to Park/Neutral Position Switch Replacement in Automatic Transmission-4L80-E in the C/K Pickup Service Manual.
  3. Turn ON the ignition, with the engine OFF.

Does the TR Sw. A/B/C/P parameter indicate HI for all range signal states?

--

Go to Step 7

Go to Step 10

7

Measure the voltage from each signal circuit of the TR switch with a DMM.

Does the DMM display near the specified value for each circuit?

10.5 V

Go to Step 8

Go to Step 12

8

  1. Jumper each signal circuit of the TR switch, one at a time, to a known good ground.
  2. With the scan tool, observe the TR Sw. A/B/C/P display as each circuit is grounded.

Do more than one circuit display LOW when a circuit is grounded?

--

Go to Step 13

Go to Step 15

9

  1. Turn OFF the ignition.
  2. Disconnect the Alternative Fuels ECM connector C001. Refer to Alternative Fuels Engine Control Module Replacement .
  3. Disconnect the TR switch connector C1. Refer to Park/Neutral Position Switch Replacement in Automatic Transmission-4L80-E in the C/K Pickup Service Manual.
  4. Turn ON the ignition, with the engine OFF.
  5. Measure the voltage from each signal circuit of the TR switch, at the harness connector of the Alternative Fuels ECM, with a DMM.

Does the DMM display near the specified value for each circuit?

10.5 V

Go to Step 17

Go to Step 18

10

  1. Turn OFF the ignition.
  2. Disconnect the Alternative Fuels ECM connector C001. Refer to Alternative Fuels Engine Control Module Replacement .
  3. With the scan tool, observe the TR Sw. A/B/C/P display.

Does the TR Sw. A/B/C/P parameter indicate HI for all range signal states?

--

Go to Step 21

Go to Step 11

11

Test the signal circuit of the TR switch that did not indicate HI for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 20

12

Test the signal circuit of the TR switch that did not display a voltage for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 16

13

Test the affected signal circuits of the TR switch for a shorted together condition. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 20

14

Test the ground circuit of the TR switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 15

15

Inspect for proper connections at the harness connector of the TR switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 19

16

Inspect for proper connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 20

17

Inspect for proper connections at the harness connector of the Alternative Fuels ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you find and correct the condition?

--

Go to Step 22

Go to Step 21

18

Repair the signal circuit of the TR switch, that did not illuminate the test lamp, for an open between the Alternative Fuels ECM and the splice. Refer to Circuit Testing and Wiring Repairs in Wiring Systems in the C/K Pickup Service Manual.

Did you complete the repair?

--

Go to Step 22

--

19

Replace the TR switch. Refer to Park/Neutral Position Switch Replacement in Automatic Transmission-4L80-E in the C/K Pickup Service Manual.

Did you complete the replacement?

--

Go to Step 22

--

20

Important: KL6 models require a switchover to gasoline with a scan tool in order to perform the Crankshaft Position Variation Learn Procedure.

KL8 models do not require the Crankshaft Position Variation Learn Procedure.

Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls in the C/K Pickup Service Manual.

Did you complete the replacement?

--

Go to Step 22

--

21

Replace the Alternative Fuels ECM. Refer to Alternative Fuels Engine Control Module Replacement .

Did you complete the replacement?

--

Go to Step 22

--

22
  1. Use the scan tool in order to clear the DTCs from the following control modules:
    2. • Alternative Fuels ECM
    • PCM
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 23

Go to Step 2

23

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK