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DTC P1852: Shift Fork 1 or 2 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 1 and 2 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
P1885: Shift fork 1 jump out
P1886: Shift fork 2 jump out
P1887: Shift fork 3 jump out
P1888: Shift fork 4 jump out

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 second or more.
Shift fork 1 and 2 current gear: Neutral.
Shift fork 1 and 2 target direction: 0 mm (0 inch) or less.

JUDGMENT CRITERIA

Shift fork 1 and 2 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 1 and 2 positions remain 1.8 mm (0.071 inch) or less for 250 milliseconds.

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 second or more.
Shift fork 1 and 2 current gear: Neutral.
Shift fork 1 and 2 target direction: 0 mm (0 inch) or more.

JUDGMENT CRITERIA

Shift fork 1 and 2 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 1 and 2 positions remain -1.8 mm (-0.071 inch) or more for 250 milliseconds.

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?

	Go to Step 2.

	Repair the CAN bus lines. (Refer to GROUP 54C - Troubleshooting .) After repairing the CAN bus line, go to Step 2.

STEP 2. Check whether the DTC is reset.

(1)Erase the DTC.

(2)With the engine idle status, operate the shift lever in the following sequence: P → R → D → R → P. (Hold each range for 1 second or more.)

(3)Check that the DTC is reset.

Q. Is the DTC No. P1852 set?

	Replace the transaxle assembly. (Refer to .)

	Intermittent malfunction. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction .)