P1855

DTC P1855: Shift Fork 3 or 4 opposite direction movement

CAUTION:

- If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.
- Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

DIAGNOSTIC FUNCTION

TC-SST-ECU checks that the movement of the shift fork is normal.

DESCRIPTIONS OF MONITOR METHODS

The movements of the shift fork 3 and 4 are determined to be abnormal.

MONITOR EXECUTION

- Continuous

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)

- P1836: Shift fork 1 malfunction
- P183D: Shift fork 2 malfunction
- P1844: Shift fork 3 malfunction
- P184B: Shift fork 4 malfunction
Sensor (The sensor below is determined to be normal)

- Not applicable

LOGIC FLOW CHARTS (Monitor Sequence)[ Functional check - move opposite direction right side]





DTC SET CONDITIONS[ FUNCTIONAL CHECK - MOVE OPPOSITE DIRECTION RIGHT SIDE]

Check Conditions

- Voltage of battery: 8 V or more.
- Voltage of battery: 16.5 V or less.
- Engine speed: 650 r/min or more.
- Time since above engine condition: 1.5 seconds or more.
- Shift fork 3 and 4 current gear: Neutral.
- Shift fork 3 and 4 target direction: 0 mm (0 inch) or less.
JUDGMENT CRITERIA

- Shift fork 3 and 4 position: 1.8 mm (0.071 inch) or more. (250 millisecond)

OBD-II DRIVE CYCLE PATTERN[ FUNCTIONAL CHECK - MOVE OPPOSITE DIRECTION RIGHT SIDE]

The shift fork 3 and 4 positions remain 1.8 mm (0.071 inch) or less for 250 millisecond.

LOGIC FLOW CHARTS (Monitor Sequence)[ Functional check - move opposite direction left side]





DTC SET CONDITIONS[ FUNCTIONAL CHECK - MOVE OPPOSITE DIRECTION LEFT SIDE]

Check Conditions

- Voltage of battery: 8 V or more.
- Voltage of battery: 16.5 V or less.
- Engine speed: 650 r/min or more.
- Time since above engine condition: 1.5 seconds or more.
- Shift fork 3 and 4 current gear: Neutral.
- Shift fork 3 and 4 target direction: 0 mm (0 inch) or more.
JUDGMENT CRITERIA

- Shift fork 3 and 4 position: -1.8 mm (-0.071 inch) or less. (250 millisecond)

OBD-II DRIVE CYCLE PATTERN[ FUNCTIONAL CHECK - MOVE OPPOSITE DIRECTION LEFT SIDE]

The shift fork 3 and 4 positions remain -1.8 mm (-0.071 inch) or more for 250 millisecond.

PROBABLE CAUSES

- Malfunction of TC-SST-ECU
- Malfunction of valve body

DIAGNOSTIC PROCEDURE

Required Special Tools:

- MB991958 Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827 M.U.T.-III USB Cable
- MB991910 M.U.T.-III Main Harness A

STEP 1. Scan tool CAN bus diagnostics

Using scan tool MB991958, diagnose the CAN bus lines.

Q. Is the check result normal?

YES Go to Step 2.
NO Repair the CAN bus lines. CAN Bus Diagnostics Chart.) After repairing the CAN bus line, go to Step 2.
STEP 2. Check whether the DTC is reset.

After driving in the 4th gear, check that the DTC is reset.

Q. Is the DTC No. P1855 set?

YES Replace the transaxle assembly. (Refer to Removal and Replacement.)
NO Intermittent malfunction. How to Cope With Intermittent Malfunctions.)