P1787
DTC P1787 (P0742): Torque Converter Clutch System (Stuck On)
DESCRIPTIONS OF MONITOR METHODS
- With PCM signal for no lock-up engagement, if vehicle speed equals or exceeds specified value, accelerator is ON, and torque converter slip amount is below specified value, PCM judges that torque converter clutch is stuck ON.
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)
- DTC P0335: Crankshaft position sensor malfunction
- DTC P1766 (P0715): Input shaft speed sensor malfunction
- DTC P1767 (P0720): Output shaft speed sensor malfunction
- DTC P1786 (P0741): Torque converter clutch system malfunction (Stuck OFF)
- DTC P1778 (P0743): Torque converter clutch solenoid malfunction
- P0122: Throttle position sensor (main) malfunction (Low input)
- P0123: Throttle position sensor (main) malfunction (High input)
- P0222: Throttle position sensor (sub) malfunction (Low input)
- P0223: Throttle position sensor (sub) malfunction (High input)
- P2135: Throttle position sensor (main and sub) range/performance problem
- P0638: Throttle actuator control motor circuit range/performance problem
- P0642: Throttle position sensor power supply
- P1601: Communication malfunction (Between PCM and throttle actuator control module)
- P0606: PCM main processor malfunction
- P2108: Throttle actuator control module processor malfunction
- P2100: Throttle actuator control motor circuit (Open)
- P2101: Throttle actuator control motor magneto malfunction
- P2102: Throttle actuator control motor circuit (Shorted low)
- P2103: Throttle actuator control motor circuit (Shorted high)
- P2122: Accelerator pedal position sensor (main) circuit low input
- P2123: Accelerator pedal position sensor (main) circuit high input
- P2127: Accelerator pedal position sensor (sub) circuit low input
- P2128: Accelerator pedal position sensor (sub) circuit high input
- P2138: Accelerator pedal position sensor (main and sub) range/performance problem
Sensor (The sensor below is determined to be normal)
- Input shaft speed sensor
- Output shaft speed sensor
- Crankshaft position sensor
- Torque converter clutch solenoid
- Throttle position sensor
- Accelerator pedal position sensor
LOGIC FLOW CHARTS (Monitor Sequence)
DTC SET CONDITIONS
Check Conditions
- Throttle position sensor voltage: 1.5 volts or more.
- Output speed: 1,000 r/min or more.
- Solenoid status: OFF.
- Transmission range switch position: D.
- Time after lock up clutch release: 5 seconds or more.
Judgement Criteria
- Calculated slip (engine speed - input speed): 5 r/min or less. (5 seconds)
- Calculated slip (engine speed - input speed): -5 r/min or more. (5 seconds)
OBD-II DRIVE CYCLE PATTERN
Start the engine, and drive at 30 km/h (19 mph) for 30 seconds. Then stop the vehicle, and turn "LOCK" (OFF) the ignition switch. After that, restart the engine, and drive again at 30 km/h (19 mph) for 30 seconds.
TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
- Malfunction of the torque converter clutch solenoid valve
- Malfunction of the valve body
- Damaged harness or connector
- Malfunction of the PCM
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Using scan tool MB991958, read the A/T diagnostic trouble code.
(1)
CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK"
(OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to the "ON" position.
(3)Check for A/T diagnostic trouble code.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is DTC P1778 (P0743) set?
YES Refer to P1778, DTC P1778 (P0743): Torque Converter Clutch Solenoid Valve System.
NO Go to Step 2.
STEP 2. Using scan tool MB991958, check data list item 10: Amount of Torque Converter Clutch Slippage.
(1)
CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK"
(OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958 to the data link connector.
(2)Start the engine. (Warming up engine)
(3)Set scan tool MB991958 to the data reading mode.
- Item 10: Torque Converter Clutch Amount of Slippage.
- Driving at a constant speed of 60 km/h (37 mph), the display should be "-10 to 10 r/min."
- If the accelerator pedal is released, the display on the scan tool changes (50 km/h (31 mph) and less).
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the torque converter clutch slippage within the specified range?
YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
NO Go to Step 3.
STEP 3. Replace the PCM.
(1)Replace the PCM. When the PCM is replaced, register the encrypted code. Encrypted Code Registration Criteria Table.
(2)Test drive the vehicle.
(3)Check for A/T diagnostic trouble code.
Q. Is DTC P1787 (P0742) set?
YES Go to Step 4.
NO The procedure is complete.
STEP 4. Replace the valve body.
(1)Replace the valve body. Transaxle Disassembly and Assembly [4A/T]
or [5A/T].
(2)Test drive the vehicle.
(3)Check for A/T diagnostic trouble code.
Q. Is DTC 53 set?
YES Replace the Torque Converter. Transaxle Disassembly and Assembly [4A/T]
or [5A/T].
NO The procedure is complete.