DTC Advanced Diagnostics: P1855
DTC P1855:Inclination Sensor Circuit Range/Performance

General Description

The acceleration sensor is built into the VSA modulator-control unit. The acceleration sensor detects the road gradient at the time of vehicle stop and outputs information to the powertrain control module (PCM). The PCM uses the acceleration sensor output received by F-CAN lines for vehicle creeping torque switching and for auto idle stop control. If the acceleration sensor output voltage is less changed during the condition there is a forward and backward acceleration, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
Depending on the driving conditions
DTC Type
Two drive cycles, MIL off, A/T gear position indicator off

Enable Conditions
Condition
Minimum
Maximum
Engine speed [Engine Speed]
500 rpm
–
Difference of front wheel right-and-left average speed and rear wheel right-and-left average speed
–
3 mph (5 km/h)
Shift lever position
Without paddle shifter
D, S, L
With paddle shifter
D, S
[ ]: HDS Parameter

Malfunction Threshold
The acceleration sensor output voltage change width is less than 0.03 V after the vehicle is driven at following conditions:
1.
Drive the vehicle at accelerator pedal position 1/16 or more and vehicle speed more than 4 mph (5 km/h) for at least 1 second.
2.
Reach the vehicle speed [Vehicle Speed] to 14 mph (21 km/h) or more.
3.
Decelerate to more than 4 mph (5 km/h) with throttle fully closed for at least 1 second.
4.
Stop the vehicle.

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.
VSA modulator-control unit internal failure (acceleration sensor)

Confirmation Procedure
Operating Condition

1.
Start the engine.
2.
With the brake pedal pressed, place the shift lever in D.
3.
Drive the vehicle at a speed of 14 mph (21 km/h) or more. (Accelerate for at least 1 second.)
4.
Release the accelerator pedal, and slow down the vehicle. (Take at least 1 second to decelerate to more than 4 mph (5 km/h).)
5.
Turn the vehicle to the OFF (LOCK) mode.
6.
Repeat Driving Pattern steps 1 through 4.
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, a Confirmed DTC and the freeze data are stored. The MIL does not come on.

Conditions for clearing the DTC
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.