P0850
DTC P0850
TAP Shift Circuit Performance:
Circuit Description
The engine control module (ECM) provides 12 volts to the park/neutral switch of the manual shift shaft position switch. The manual shift shaft position switch is a sliding contact assembly that attaches to the manual shift shaft inside the transmission. The switch consists of five separate circuits, four of which indicate gear selector position to the transmission control module (TCM), and one that indicates park/neutral position to the ECM. When the transmission is in Park or Neutral, the switch closes and pulls the ECM voltage low, 0 volts. When the transmission is not in Park or Neutral, the ECM voltage is high, 12 volts. The ECM uses the switch in order to enable starter operation.
If the Park/Neutral switch and the transmission manual shift shaft position switch do not agree for a specified length of time, DTC P0850 sets. DTC P0850 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0850 Park/Neutral Position (PNP) Switch Circuit
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
DTC P0850 sets when either of the following conditions are true:
Condition 1
The park/neutral switch circuit is low, 0 volts, for 100 seconds while the TCM is reporting the gear selector is in REVERSE or any forward range.
Condition 2
The park/neutral switch circuit is high, 12 volts, for 200 seconds while the TCM is reporting the gear selector is in PARK or NEUTRAL.
Action Taken When the DTC Sets
* The ECM does not illuminate the malfunction indicator lamp (MIL).
* The ECM uses the transmission range data to enable engine cranking.
* The ECM stores the operating conditions when the Conditions for Setting the DTC are met. This information is stored as a Failure Record.
* The ECM stores DTC P0850 in ECM history.
Conditions for Clearing the MIL/DTC
* The ECM clears the DTC from ECM history if the vehicle completes 40 warm-up cycles without a non emission diagnostic fault occurring.
* The ECM cancels the default action when the ignition is OFF long enough in order to power down the ECM.
* A scan tool can clear the DTC.
