P1778

DTC P1778 (P0743): Torque Converter Clutch Solenoid Valve System

SOLENOID VALVE SYSTEM CIRCUIT

Refer to P1773.

CIRCUIT OPERATION

Refer to P1773.

DESCRIPTIONS OF MONITOR METHODS

- If lock-up is not engaged, and solenoid terminal voltage is below specified value, PCM judges that torque converter clutch solenoid valve has a failure.

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 P1779 (P0731): 1st gear incorrect ratio
- DTC P1780 (P0732): 2nd gear incorrect ratio
- DTC P1781 (P0733): 3rd gear incorrect ratio
- DTC P1782 (P0734): 4th gear incorrect ratio
- DTC P1783 (P0735): 5th gear incorrect ratio[ 5A/T]
- DTC P1784 (P0736): Reverse gear incorrect ratio
- DTC P1773 (P0753): Low-reverse solenoid malfunction
- DTC P1774 (P0758): Underdrive solenoid malfunction
- DTC P1775 (P0763): Second solenoid malfunction
- DTC P1776 (P0768): Overdrive solenoid malfunction
- DTC P1777 (P0773): Reduction solenoid malfunction[ 5A/T]
- DTC P1788 (P1751): A/T control relay malfunction
Sensor (The sensor below is determined to be normal)

- Low-reverse solenoid
- Underdrive solenoid
- Second solenoid
- Overdrive solenoid
- Reduction solenoid[ 5A/T]
- A/T control relay

LOGIC FLOW CHARTS (Monitor Sequence)





DTC SET CONDITIONS

Check Conditions

- Solenoid status: either solid ON or OFF.
- Voltage of battery: 10 volts or more.
Judgement Criteria

- Solenoid voltage: 3 volts or less. (0.3 second)
- If DTC P1778 (P0743) is set consecutively four times, the transaxle is locked into 3rd gear as a fail-safe measure, and the selector lever position indicator light (D, 1 through 4 or 5) flashes once per second.

OBD-II DRIVE CYCLE PATTERN

Start the engine, and keep the vehicle stopped in "P" range for 5 seconds.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)

- Malfunction of the torque converter clutch solenoid valve
- 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, check actuator test item 6: Torque Converter Clutch Solenoid Valve.





(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)Set scan tool MB991958 to the actuator test mode.

- Item 6: Torque Converter Clutch Solenoid Valve.
- An audible clicking or buzzing should be heard when the torque converter clutch solenoid valve is energized.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the solenoid valve operating properly?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

NO Go to Step 2.

STEP 2. Using scan tool MB991958, read the A/T diagnostic trouble code.





(1)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 P1788 (P1751) set? (DTC P1788 (P1751) may be set along with multiple DTCs).

YES Refer to P1788 DTC P1788 (P1751): A/T Control Relay System.

NO Go to Step 3.

STEP 3. Using scan tool MB991958, read the A/T diagnostic trouble code.





(1)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 31 set?

YES Go to Step 8.

NO Go to Step 4.

STEP 4. Measure the torque converter clutch solenoid valve resistance at A/T control solenoid valve assembly connector B-111.





(1)Disconnect connector B-111 and measure at the solenoid valve side.





(2)Measure the resistance between solenoid valve assembly connector B-111 terminals 7 and 10.
Resistance value: 2.7-3.4ohms [at 20°C (68°F)]

Q. Is the measured resistance 2.7-3.4ohms [at 20°C (68°F)]?

YES Go to Step 6.

NO Go to Step 5.

STEP 5. Measure the solenoid valve resistance at the torque converter clutch solenoid valve assembly inside the transaxle.





(1)Disconnect connector B-111-4 and measure at the solenoid valve side.





(2)Measure the resistance between torque converter clutch solenoid valve terminals 1 and 2.
Resistance value: 2.7-3.4ohms [at 20°C (68°F)]

Q. Is the measured resistance 2.7-3.4ohms [at 20°C (68°F)?

YES Replace the harness wire between A/T control solenoid valve assembly connector B-111 and the solenoid valves.

NO Replace the torque converter clutch solenoid valve. Valve Body Disassembly and Assembly Valve Body [4A/T] or Valve Body [5A/T].

STEP 6. Check PCM connector B-20 and A/T control solenoid valve assembly connector B-111 for loose, corroded or damaged terminals, or terminals pushed back in the connector.









Q. Are the connectors and terminals in good condition?

YES Go to Step 7.

NO Repair or replace the damaged components. Harness Connector Inspection.

STEP 7. Check the harness for an open or short circuit to ground between PCM connector B-20 terminal 54 and A/T control solenoid valve assembly connector B-111 terminal 7.









Q. Is the harness wire in good condition?

YES Replace the PCM. When the PCM is replaced, register the encrypted code. Immobilizer System.

NO Repair or replace the harness wire.

STEP 8. Measure the supply voltage at A/T control solenoid valve assembly connector B-111.





(1) Disconnect solenoid valve assembly harness connector B-111.
(2)Turn the ignition switch to the "ON" position.





(3)Measure the voltage between harness connector B-111 terminal 10 and ground.

- The voltage should equal battery positive voltage.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the measured voltage battery positive voltage?

YES Go to Step 11.

NO Go to Step 9.

STEP 9. Check A/T control relay connector B-15X in the engine component relay box and A/T control solenoid valve assembly connector B-111 for loose, corroded or damaged terminals, or terminals pushed back in the connector.









Q. Are the connectors and terminals in good condition?

YES Go to Step 10.

NO Repair or replace the damaged components. Harness Connector Inspection.

STEP 10. Check the harness for an open circuit or short circuit to ground between A/T control relay connector B-15X terminal 4 in the engine component relay box and A/T control solenoid valve assembly connector B-111 terminal 10.









Q. Is the harness wire in good condition?

YES Go to Step 11.

NO Repair or replace the harness wire.

STEP 11. Check PCM connector B-20 and A/T control solenoid valve assembly connector B-111 for loose, corroded or damaged terminals, or terminals pushed back in the connector.









Q. Are the connectors and terminals in good condition?

YES Go to Step 12.

NO Repair or replace the damaged components. Harness Connector Inspection.

STEP 12. Check the harness for an open or short circuit to ground between PCM connector B-20 (terminals 54, 56 and 53 [5A/T]) and A/T control solenoid valve assembly connector B-111 (terminals 6, 7 and 8 [5A/T]).









Q. Are the harness wires in good condition?

YES Go to Step 13.

NO Repair or replace the harness wire.

STEP 13. Check the harness for an open or short circuit to ground between A/T control solenoid valve assembly connector B-111 (terminals 6, 7, 8 [5A/T] and 10) and solenoid valve connectors B-111-4 and B-111-5 and B-111-6 [5A/T].









Q. Is the harness wire in good condition?

YES Replace the PCM. When the PCM is replaced, register the encrypted code. Immobilizer System.

NO Replace the harness wire.