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MONITOR DESCRIPTION
The ECM detects vehicle speed as pulse signal using a vehicle speed sensor.
The transmission output shaft speed (NC) sensor built into the transmission detects vehicles speed signals (pulse signals). These signals are sent to the ECM via the combination meter.
If the ECM does not detect any vehicle speed signals while the vehicle is being driven, the ECM interprets it as a malfunction in the vehicle speed sensor circuit and sets a DTC.
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The park/neutral position switch detects the gearshift position and sends the shifter position signal to the ECM. For safety, the engine can be started only when the vehicle is in the P or N gear position.
The ECM will conclude that there is a malfunction if it detects that the park/neutral position switch sent either P or N position signal to the ECM while driving. The ECM will illuminate the MIL and set a DTC.
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The ATF temperature sensor converts ATF temperature value into an electrical resistance. Based on the resistance, the ECM calculates the ATF temperature and detects an open or short in the ATF temperature circuit.
If the resistance value of ATF temperature is less than 79 *1 or more than 156 k *2 , the ECM interprets this as a fault in the ATF temperature sensor or wiring. The ECM will turn on the MIL and set the DTC.
*1 : 150°C (302°F) or more is indicated regardless of the actual ATF temperature.
*2 : -40°C (-40°F) is indicated regardless of the actual ATF temperature.
HINT
The ATF temperature can be checked with the OBD II scan tool or hand-held tester.
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The ATF temperature sensor converts ATF temperature value to an electrical resistance. Based on the resistance, the ECM calculates the ATF temperature. The ECM can also detect an open or short in the ATF temperature circuit.
After running the vehicle for a certain period, the ATF temperature should increase. If the ATF temperature is still less than 10°C (50°F) even after the driving time criteria have been satisfied, the ECM will conclude that there is a malfunction in the ATF temperature sensor. The ECM will illuminate the MIL and a DTC is set.
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The NT terminal of the ECM detects the revolving signal from the speed sensor (NT) (input rpm). The ECM outputs a gear shift signal comparing the speed sensor (NT) with the speed sensor (SPD).
While the vehicle is operating in the 2nd, 3rd or O/D gear position in the shift position of D, if the input shaft revolution is less than 300 rpm *1 although the output shaft revolution is more than 1,000 rpm *2 , the ECM interprets this as a malfunction, illuminates the MIL and stores the DTC.
*1 : Pulse is not output or is irregularly output.
*2 : The vehicle speed is 50 km/h (31 mph) or more.
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This circuit prevents the engine from stalling when the vehicle is suddenly braked while the torque converter is in the lock-up condition. The ECM receives the signal from the stop light switch at the time brake pedal is depressed. Then, the ECM stops sending the "lock-up" command to the lock-up solenoid valve and the torque converter clutch "unlocks". The ECM monitors the brake light switch "B" signal. If the ECM detects that the switch remains ON while the vehicle is in "stop and go" driving conditions, it will illuminate the MIL and set a DTC.
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Torque converter lock-up is controlled by the ECM based on speed sensor signal (NT), speed sensor signal (NC), engine rpm, engine load, engine temperature, vehicle speed, transmission temperature, and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine rpm (NE) to the input turbine rpm (NT). The ECM calculates the actual transmission gear by comparing input turbine rpm (NT) to counter gear rpm (NC). When the conditions are appropriate, the ECM requests "lock-up" by applying control voltage to shift solenoid DSL. When the DSL is turned on, solenoid DSL applies pressure to the lock-up relay valve and locks the torque converter clutch.
If the ECM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the ECM interprets this as a fault in the torque converter clutch performance. The ECM will turn on the MIL and store the DTC.
Example
When any of the following is met, the system judges it as a malfunction.
- There is a difference in rotation between before and after torque converters even when the ECM commands lock-up. (Engine speed is at least 100 rpm greater than input speed.)
- There is no difference in rotation between before and after torque converters even when the ECM commands lock-up off. (The difference between engine speed and input speed is less than 35 rpm.)
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- Check other DTCs output (in addition to DTC P0741). PREPARATION: Warm up the engine. Turn the ignition switch OFF. Connect the hand-held tester or the OBD II scan tool to the DLC3. Turn the ignition switch ON. Turn ON the hand-held tester or the OBD II scan tool. Enter the following menus: DIAGNOSIS/ENHANCED OBD II/DTC INFO/CURRENT CODES. CHECK: Read the DTCs using the hand-held tester or the OBD II scan tool. RESULT: RESULT DISPLAY Display (DTC output) Proceed to Only "P0741" is output A "P0741" and other DTCs B HINT: If any other codes besides "P0741" is output, perform the troubleshooting for those DTCs first. B: Go to relevant DTC chart (See «DIAGNOSTIC TROUBLE CODE CHART»(ref-180980-S29793334842005073000000) ). A: Go to next step.
- Check transmission wire (DSL). PREPARATION: Disconnect the transmission wire connector from the transaxle. CHECK: Measure the resistance between terminal DSL of the transmission wire connector and body ground. OK: Resistance: 11 to 15 ohm at 20°C (68°F) NG : Go to step 5 . OK : Go to next step.
- Check resistance between terminal DSL of ECM connector and body ground. PREPARATION: Connect the transmission wire connector. Disconnect the E5 ECM connector. CHECK: Measure the resistance between terminals DSL of the ECM connector and body ground. OK: Resistance: 11 to 15 ohm at 20°C (68°F) NG: Repair or replace harness or connector (See «HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE»(ref-180907-S19852941862005073000000) ). OK: Check and replace ECM (See «HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE»(ref-180907-S19852941862005073000000) ).
- Check shift solenoid valve DSL. PREPARATION: Jack up the vehicle. Remove the oil pan. Disconnect the shift solenoid valve DSL connector. Remove the shift solenoid valve DSL. CHECK: Measure the resistance between terminal DSL of the shift solenoid valve and the solenoid body. Connect the positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body. OK: Resistance: 11 to 15 Q. The shift solenoid valve DSL makes the operation noise. NG : Replace shift solenoid valve DSL. OK : Go to next step.
- Check transmission wire (open or short). NG : Repair or replace transmission wire. OK : Go to next step.
- Check valve body (see chapter 2 in problem symptom table) (See «PROBLEM SYMPTOMS TABLE»(ref-180980-S07267908642005073000000) ). NG: Repair or replace valve body. OK: Go to next step.
- Check torque converter clutch (See «INSPECTION»(ref-181124-S08986891612005073100000) ). NG: Replace torque converter clutch. OK: Repair or replace automatic transaxle assembly (See «REMOVAL»(ref-181124-S29345681142005073100000) ).
The ECM commands transmission gear shifts by turning the shift-solenoid valves ON and OFF. Using the signals from the input speed sensor (input shaft speed) and the output speed sensor (output shaft speed or counter shaft speed), the ECM calculates the actual gear position [1st, 2nd, 3rd, 4th gear position]. When the gear position indicated by the ECM and the actual gear position are not the same, the ECM illuminates the MIL and a DTC is set.
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The ECM commands transmission gear shifts by turning the shift-solenoid valves ON and OFF. If the ECM detects an open or short circuit in any shift-solenoid valve, it will illuminate the MIL and a DTC is set. At this time, the ECM will enter fail-safe mode. The ECM will stop sending command signal(s) to the malfunctioning solenoid but continue to operate the other solenoid valves to provide partial transmission operation.
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The counter gear speed sensor detects the output shaft speed. The ECM compares the input shaft speed with the output shaft speed to control the hydraulic pressure during gear change.
If the ECM fails to receive the input shaft speed signal, it estimates the input shaft speed based on the output shaft speed and sets the hydraulic pressure. (Fail-safe operation) At this time the ECM illuminates the MIL and set a DTC.
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The ECM sends signals (duty ratio) to the shift solenoid valve (SLT) according to the signals from the throttle position sensor, speed sensor, etc. Based on the signal's duty ratio, the shift solenoid valve adjusts the hydraulic pressure on the primary regulator valve. This system allows smooth vehicle control by adjusting the line hydraulic pressure to the engine output and driving conditions.
The ECM turns on the MIL and sets a DTC when an open or short circuit is detected in the shift solenoid valve SLT circuit.
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Torque converter lock-up is controlled by the ECM based on engine rpm, engine load, engine temperature, vehicle speed, transmission temperature, and shift range selection. The ECM determines the lock-up status of the torque converter by comparing the engine rpm (NE) to the input turbine rpm (NT). The ECM calculates the actual transmission gear by comparing the input turbine rpm (NT) to counter gear rpm (NC). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to the shift solenoid DSL. When the DSL is opened, solenoid DSL applies pressure to the lock-up relay valve and locks the torque converter clutch. If the ECM detects an open or short in the DSL solenoid circuit, the ECM interprets this as a fault in the DSL solenoid or circuit. The ECM will turn on the MIL and store DTC.
