GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 Vibe - AWD 🢒 DTC 🢒 DTC P0850

Circuit Description

The park/neutral position (PNP) switch detects the gearshift position and signals these positions to the powertrain control module (PCM). The PNP switch detects the gear shift position so the engine can only be started in the PARK or NEUTRAL positions.

DTC P0850 will set if the PCM detects start-up in a drive range or vehicle speed in the PARK or NEUTRAL range. DTC P0850 is a type C DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0850 PARK/NEUTRAL Switch Open

Conditions for Setting the DTC

The PCM detects when the PNP switch remains ON (P or N position) when the vehicle speed is 77 km/h (44 mph) or more and the engine speed is between 1,500-3,500 RPM.

Action Taken When the DTC Sets
    • The PCM does illuminate the malfunction indicator lamp (MIL).
    • The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
    • The PCM stores DTC P0850 in PCM history.

Conditions for Clearing the DTC
    • A scan tool can clear the DTC.
    • The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
    • The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

Test Description

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

  1. Disconnecting the transmission range switch, the ground path of all PNP switch circuits would be removed and the PCM would recognize all circuits as open. The scan tool will display HI for all range signals.

    2.

  2. This step verifies the repair of the PNP switch wiring for an open or the lack of the signal voltage from the PCM.

DTC P0850

Step

Action

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Select PNP Sw. on the scan tool.
  4. With the scan tool, observe the PNP Sw. display while selecting each transmission range: P, R, N, D, 2 and L.

Does each selected transmission range match the scan tool PNP display?

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Inspect the park/neutral position (PNP) switch assembly for the following:
    3. • Damage
    • Loose or missing mounting hardware
    • Proper adjustment

Did you find and correct a condition?

Go to Step 9

Go to Step 4

4

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

Does the scan tool PNP Sw. A/B/C/P parameter indicate HI for all range, signal states?

Go to Step 5

Go to Step 8

5

Test the affected signal circuits of the PNP switch for a short to ground.

Did you find and correct the condition?

Go to Step 9

Go to Step 6

6

Test the ground circuit of the PNP switch for a open.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

7

Replace the PNP switch. Refer to Park/Neutral Position Switch .

Did you complete the replacement?

Go to Step 9

--

8

Replace the powertrain control module (PCM). Refer to Powertrain Control Module Programming and Setup in Programming and Setup.

Did you complete the replacement?

Go to Step 9

--

9

Perform the following procedures in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Drive the vehicle greater than 8 km/h (5 mph) for a short distance, then stop the vehicle.
  4. Select each transmission range: P, R, N, D, 2 and L.
  5. Place the transmission in PARK.
  6. Select Specific DTC. Enter DTC P0705.

Has the test run and passed?

Go to Step 10

Go to Step 2

10

With the scan tool, observe the stored information, capture info, and DTC Info.

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

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK