DTC Advanced Diagnostics: P1844
DTC P1844:CVT Input Shaft Speed Sensor Circuit Forward Rotation Range/Performance

General Description


Tr1
Tr2
Pulse signal voltage level
OFF
OFF
VOH
OFF
ON
VOM
ON
OFF
VOL

The CVT drive pulley speed sensor is attached to the outside of the end cover. The CVT drive pulley speed sensor consists of a semiconductor to detect the position of the drive pulley. When the drive pulley rotates, the magnetic flux in the CVT drive pulley speed sensor changes. The changes of magnetic flux are converted into pulsing signals to the transmission control module (TCM). The rotational direction of the drive pulley is detected by the voltage level of the pulsing signals. If the driving condition and the detected voltage level of the pulsing signals do not match, the TCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
2 seconds or more
DTC Type
Two drive cycles, MIL off, Shift position indicator blinks

Enable Conditions
Condition
Minimum
Maximum
Elapsed time after forward clutch engage completion
3 seconds
–
Engine speed [Engine Speed]
500 rpm
–
Forward clutch commanded pressure
295 kPa (3.0 kgf/cm2, 42.7 psi)
–
Vehicle speed [Vehicle Speed]
19 mph (30 km/h)
–
Shift lever position/mode
Without paddle shifter
D, S, L
With paddle shifter
D, S
Other
Not when the shift lever is being shifted
Rotation speed [Secondary Shaft Speed 1 (rpm)] measured by CVT speed sensor is more than 500 rpm
Rotational direction [Direction of Secondary-shaft Rotation] measured by CVT speed sensor is forward direction
[ ]: HDS Parameter

Malfunction Threshold
The CVT drive pulley speed sensor outputs [Direction of Drive Pulley Rotation] a reverse direction signal for at least 2 seconds when driving in forward position.

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.
CVT drive pulley speed sensor failure
TCM internal circuit failure

Confirmation Procedure
Operating Condition

1.
Start the engine.
2.
Drive the vehicle in D position/mode at a speed of 19 mph (30 km/h) or more for at least 5 seconds.
3.
Slow down and stop the vehicle.
4.
Turn the vehicle to the OFF (LOCK) mode.
5.
Repeat Driving Pattern steps 1 through 3.
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 TCM memory. If the malfunction returns in the next (second) drive cycle, the shift position indicator blinks and a Confirmed DTC and the freeze data are stored. The MIL does not come on.

Conditions for clearing the DTC
The shift position indicator comes off by turning the vehicle to the OFF (LOCK) mode. The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command.