DTC Advanced Diagnostics: P0812
DTC P0812:Transmission Range Switch ATP-R Switch

General Description

Transmission range switch contact point input matrix

Shift lever position
Input per switch
ATP-P
ATP-R
ATP
RVS
ATPN
ATPD
ATPS
ATP
FWD
P
O
X
X
X
X
X
X
R
X
O
O
X
X
X
X
N
X
X
X
O
X
X
X
D
X
X
X
X
O
X
O
S
X
X
X
X
X
O
O
O: Closed X: Open


The transmission range switch is attached to a control shaft. Operating the shift lever makes the control shaft rotate via the shift cable. The A/T gear position indicator shows which position is selected according to the Low/High signal combinations, which vary based on the control shaft rotational angle. The control shaft changes the position of the transmission range switch, activates the manual valve, and switches hydraulic pressure to shift the transmission through forward/neutral/reverse. The transmission range switch signal is used to determine the shift schedule. The voltage is high (5 V or 12 V) at the powertrain control module (PCM) input terminal when each transmission range switch position is open, and it is low (0 V) when each switch is closed. If the R switch is open while driving the vehicle in R, the PCM detects an R switch open failure and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status
Execution
Continuous
Sequence
None
Duration
Depending on the driving conditions
DTC Type
Two drive cycles, MIL on, A/T gear position indicator blinks
OBD Status
PASSED/FAILED/NOT COMPLETED (STILL TESTING)

Enable Conditions
Condition
Minimum
Maximum
Engine speed
[ENGINE SPEED]
1,000 rpm
–
Battery voltage
[BATTERY VOLTAGE]
11 V
–
Shift lever position
R
No active DTCs set (prevents monitor from running)
P0705, P0716, P0717, P0721, P0722, P1717
[ ]: HDS Parameter

Malfunction Threshold
The RVS position signal input [Reverse Switch(ATPRVS)] is detected but the R position signal input [A/T R Switch] is not detected.

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Transmission range switch ATP-R line open (includes connector loose connection or disconnection)
Transmission range switch failure
Shift cable adjustment failure
PCM internal circuit failure

Confirmation Procedure
Operating Condition

1.
Start the engine.
2.
Drive the vehicle in R at 3 mph (5 km/h) or less for at least 2 seconds.
3.
Drive the vehicle in R at 3 mph (5 km/h) or more for at least 2 seconds.
Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
With the HDS
None.

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on, the A/T gear position indicator blinks, and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The A/T gear position indicator comes off by pressing the engine start/stop button to select the OFF mode. The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command.