P1844
DTC P1844: Shift Fork 3 MalfunctionCAUTION:
^ 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 3 is normal.
DESCRIPTIONS OF MONITOR METHODS
The movement of the shift fork 3 is 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
^ P1834B: Shift fork 4 malfunction
Sensor (The sensor below is determined to be normal)
^ Not applicable
LOGIC FLOW CHARTS (Monitor Sequence) [Functional check-blocked]
DTC SET CONDITIONS [FUNCTIONAL CHECK-BLOCKED]
Check Conditions
^ Voltage of battery: 8 V or more.
^ Voltage of battery: 16.5 V or less.
^ Engine speed: 500 r/min or more.
^ Time since above engine condition: 400 millisecond or more.
^ Common high side 1 voltage: 2.5 V or more.
^ Common high side 2 voltage: 2.5 V or more.
JUDGMENT CRITERIA
^ Shift fork operation time: Shift fork operation time (threshold value) or more. (immediately)
^ Shift fork operation time (threshold value): Equal the maximum allowed time x Coefficient. (immediately)
OBD-II DRIVE CYCLE PATTERN [FUNCTIONAL CHECK-BLOCKED]
The shift fork operation time is threshold value or less.
LOGIC FLOW CHARTS (Monitor Sequence) [Functional check-6th gear]
DTC SET CONDITIONS [FUNCTIONAL CHECK-6TH GEAR]
Check Conditions
^ Voltage of battery: 8 V or more.
^ Voltage of battery: 16.5 V or less.
^ Engine speed: 500 r/min or more.
^ Time since above engine condition: 400 millisecond or more.
^ Shift fork 3 current gear: 6th gear.
JUDGMENT CRITERIA
^ Shift fork position: -6 mm (-0.24 inch) or more, and input shaft 2 (even) speed: 500 r/min or more, or synchro (6th gear) slip speed: 80 r/min or more. (400 millisecond)
OBD-II DRIVE CYCLE PATTERN [FUNCTIONAL CHECK-6TH GEAR]
The status with the shift fork position -6 mm (-0.24 inch) or less, or with the input shaft 2 (even) speed 500 r/min or less and with the synchro (6th gear) slip speed 80 r/min or less continues for 400 milliseconds.
LOGIC FLOW CHARTS (Monitor Sequence) [Functional check-Neutral]
DTC SET CONDITIONS [FUNCTIONAL CHECK-NEUTRAL]
Check Conditions
^ Voltage of battery: 8 V or more.
^ Voltage of battery: 16.5 V or less.
^ Engine speed: 500 r/min or more.
^ Time since above engine condition: 400 millisecond or more.
^ Shift fork 3 current gear: Neutral.
JUDGMENT CRITERIA
^ Shift fork position: 1.8 mm (0.071 inch) or more. (250 millisecond)
OBD-II DRIVE CYCLE PATTERN [FUNCTIONAL CHECK-NEUTRAL]
The shift fork position remains 1.8 mm (0.071 inch) or less for 250 milliseconds.
LOGIC FLOW CHARTS (Monitor Sequence)
[Functional check-Shift fork 3 requested but shift fork 1 movement]
DTC SET CONDITIONS [FUNCTIONAL CHECK SHIFT FORK 3 REQUESTED BUT SHIFT FORK 1 MOVEMENT]
Check Conditions
^ Voltage of battery: 8 V or more.
^ Voltage of battery: 16.5 V or less.
^ Engine speed: 500 r/min or more.
^ Time since above engine condition: 400 millisecond or more.
^ Requested shift fork: Shift fork 3.
JUDGMENT CRITERIA
^ Shift fork position: 6 mm (0.24 inch) [1st gear side] or less, or -6 mm (-0.24 inch) [reverse gear side] or more, or 1.8 mm (0.071 inch) [neutral position] or more and initialized fork position shift fork 3 position: 2.5 mm (0.098 inch) or less. (200 millisecond)
OBD-II DRIVE CYCLE PATTERN [FUNCTIONAL CHECK-SHIFT FORK 3 REQUESTED BUT SHIFT FORK 1 MOVEMENT]
The status with the shift fork position 6 mm (0.24 inch) [1st gear side] or more, or with -6 mm (-0.24 inch) [reverse gear side] or less, or with 1.8 mm (0.071 inch) [neutral position] or less and with the initialized fork position-shift fork 3 position 2.5 mm (0.098 inch) or more continues for 200 milliseconds.
LOGIC FLOW CHARTS (Monitor Sequence)
[Functional check-shift fork 3 requested but shift fork 4 movement]
DTC SET CONDITIONS [FUNCTIONAL CHECK-SHIFT FORK 3 REQUESTED BUT SHIFT FORK 4 MOVEMENT]
Check Conditions
^ Voltage of battery: 8 V or more.
^ Voltage of battery: 16.5 V or less.
^ Engine speed: 500 r/min or more.
^ Time since above engine condition: 400 millisecond or more.
^ Requested shift fork: Shift fork 3.
JUDGMENT CRITERIA
^ Shift fork position: 6 mm (0.24 inch) [4th gear side] or less, or -6 mm (-0.24 inch) [2nd gear side] or more, or 1.8 mm (0.071 inch) [neutral position] or more, and initialized fork position-shift fork 3 position: 2.5 mm (0.098 inch) or less. (200 millisecond)
OBD-II DRIVE CYCLE PATTERN [FUNCTIONAL CHECK-SHIFT FORK 3 REQUESTED BUT SHIFT FORK 4 MOVEMENT]
The status with the shift fork position 6 mm (0.24 inch) [4th gear side] or more, or with -6 mm (-0.24 inch) [2nd gear side] or less, or with 1.8 mm (0.071 inch) [neutral position] or less and with the initialized fork position-shift fork 3 position 2.5 mm (0.098 inch) or more continues for 200 milliseconds.
PROBABLE CAUSES
^ Malfunction of TC-SST-ECU
^ Malfunction of TC-SST shift fork
DIAGNOSTIC PROCEDURE
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. After repairing the CAN bus line, go to Step 2.
STEP 2. Check whether the DTC is reset.
Q: Is DTC No. P1844 set?
YES: Replace the TC-SST assembly.
NO: Intermittent malfunction.