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DTC P1806: Shift Fork Position Sensor 3 and 4 System (Power supply voltage low range out)

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 supply voltage to the shift fork position sensor 3 and 4 is normal.

DESCRIPTIONS OF MONITOR METHODS

The supply voltage to the shift fork position sensor 3 and 4 is too low.

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)

P182A: Shift fork position sensor 3 system (Voltage low range out)
P182B: Shift fork position sensor 3 system (Voltage high range out)
P182C: Shift fork position sensor 3 system (Output range out)
P182E: Shift fork position sensor 3 system (Poor performance)
P1831: Shift fork position sensor 4 system (Voltage low range out)
P1832: Shift fork position sensor 4 system (Voltage high range out)
P1833: Shift fork position sensor 4 system (Output range out)
P1835: Shift fork position sensor 4 system (Poor performance)
P1836: Shift fork 1 malfunction
P183D: Shift fork 2 malfunction
P1844: Shift fork 3 malfunction
P184B: Shift fork 4 malfunction
P1852: Shift fork 1 or 2 opposite direction movement
P1855: Shift fork 3 or 4 opposite direction movement
P1857: Odd number gear axle interlock
P1858: Even number gear axle interlock
P1876: Gear block 1st
P1877: Gear block 2nd
P1878: Gear block 3rd
P1879: Gear block 4th
P187A: Gear block 5th
P187B: Gear block 6th
P187C: Gear block reverse
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)

Shift fork position sensor 3
Shift fork position sensor 4

LOGIC FLOW CHARTS (Monitor Sequence)

DTC SET CONDITIONS

Check Conditions

Voltage of battery: 8 V or more.
Voltage of battery: 16.5 V or less.

JUDGMENT CRITERIA

Supply voltage: 3.07 V or less. (140 millisecond)

OBD-II DRIVE CYCLE PATTERN

The supply voltage remains 3.07 V or more for 140 milliseconds.

PROBABLE CAUSES

Malfunction of TC-SST-ECU
Malfunction of shift fork position sensor 3 and 4

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 the TC-SST-ECU power supply circuit

Refer to

.

Q. Is the check result normal?

	Go to Step 3.

	Repair the TC-SST-ECU power supply circuit. (Refer to .) After repairing the power supply circuit, go to Step 3.

STEP 3. Check whether the DTC is reset.

Q. Is DTC No. P1806 set?

	Replace the transaxle assembly. (Refer to .)

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