Smart Access System (Keyless Start) (Diagnostic Codes & Symptom Tests): Overview Lexus RX III

Scheme 64

1. CHECK POWER SOURCE MODE CHANGE FUNCTION Check the function of the engine switch. Check that power source mode changes in accordance with the conditions of the shift position and brake pedal. Brake Pedal Shift Lever Power Source Mode Pattern Depressed P or N When the engine switch is pushed once. off --> engine start Not depressed P Each time the engine switch is pushed. off --> on (ACC) --> on (IG) --> off Except P Each time the engine switch is pushed. off --> on (ACC) --> on (IG) --> on (ACC) - P When the engine switch is pushed in the on (IG) condition (engine running). on (IG) --> off - Except P When the engine switch is pushed in the on (IG) condition (engine running). on (IG) --> on (ACC) Check that the power source mode changes without pressing the engine switch. With power source mode on (ACC) and the shift lever in P, wait for either 20 minutes or 60 minutes. Check that the power source mode changes from on (ACC) to off automatically.
2. CHECK INDICATOR CONDITION Check the indicator light on the engine switch. Check that the engine switch indicator turns on and changes color according to the table below. Power Source Mode/Condition Indicator Light Condition Brake Pedal Released Brake Pedal Depressed, Shift Lever in P or N off off Turns on (Green) on (ACC, IG) Turns on (Amber) Turns on (Green) Engine running off off Steering lock not unlocked Flashes (Green) for 30 sec. Flashes (Green) for 30 sec. System malfunction Flashes (Amber) for 15 sec. Flashes (Amber) for 15 sec.

DESCRIPTION

This DTC is stored when a problem such as an open in the AM2 fuse, an open or short in the wire harness between the fuse and power management control ECU, a short in the IG output circuit inside the power management control ECU, a short between the power management control ECU and relay, or a short in the relay is detected.

Scheme 65

This DTC is stored when a problem such as an open in the AM2 fuse, an open or short in the wire harness between the fuse and power management control ECU, a short in the IG output circuit inside the power management control ECU, a short between the power management control ECU and relay, or a short in the relay is detected.

This DTC is stored when there is a problem in the ACC output circuit. The ACC circuit is the circuit that goes from inside the power management control ECU to the ACC relay.

Scheme 66

This DTC is stored when there is a problem in the ACC output circuit. The ACC circuit is the circuit that goes from inside the power management control ECU to the ACC relay.

This DTC is stored when the submersion circuit monitor inside the power management control ECU detects a large amount of water.

This DTC is stored when the submersion circuit monitor inside the power management control ECU detects a large amount of water.

The power management control ECU receives vehicle speed information using 2 methods. It receives a speed signal from the meter ECU. It also receives speed information from the meter ECU via CAN. If the information sent using these 2 methods is inconsistent, this DTC will be stored.

Scheme 67

HINT

1. A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter. The signal is changed to a pulse signal at the transistor in the combination meter. Each ECU controls the respective system based on the pulse signal.
2. If a short occurs in an ECU, all systems in the diagram above will not operate normally.

The power management control ECU receives vehicle speed information using 2 methods. It receives a speed signal from the meter ECU. It also receives speed information from the meter ECU via CAN. If the information sent using these 2 methods is inconsistent, this DTC will be stored.

The skid control ECU converts wheel speed sensor signals into 4-pulse signals and sends them to the combination meter. After this signal is converted into a more precise rectangular waveform see scheme 43 by the waveform shaping circuit inside the combination meter, it is then transmitted to the power management control ECU. The power management control ECU determines the vehicle speed based on the frequency of these pulse signals.

The skid control ECU converts wheel speed sensor signals into 4-pulse signals and sends them to the combination meter. After this signal is converted into a more precise rectangular waveform by the waveform shaping circuit inside the combination meter, it is then transmitted to the power management control ECU. The power management control ECU determines the vehicle speed based on the frequency of these pulse signals.

The power management control ECU receives brake signal information from 2 sources. It receives a signal from the stop light switch assembly via a direct line, and a signal from the ECM via CAN. If the information from these 2 sources is inconsistent, this DTC will be stored.

Scheme 68

The power management control ECU receives brake signal information from 2 sources. It receives a signal from the stop light switch assembly via a direct line, and a signal from the ECM via CAN. If the information from these 2 sources is inconsistent, this DTC will be stored.

This DTC is stored when serial communication signals and LIN communication signals in the circuit between the power management control ECU and steering lock actuator assembly (steering lock ECU) are inconsistent.

Scheme 69

This DTC is stored when serial communication signals and LIN communication signals in the circuit between the power management control ECU and steering lock actuator assembly (steering lock ECU) are inconsistent.

The power management control ECU receives an engine speed signal and information that indicates whether the engine is running or not. It receives the engine speed signal from the ECM via a direct line, and the information about whether the engine is running is received from the ECM via CAN. If the information sent using these 2 methods is inconsistent, these DTCs will be stored.

Scheme 70

The power management control ECU receives an engine speed signal and information that indicates whether the engine is running or not. It receives the engine speed signal from the ECM via a direct line, and the information about whether the engine is running is received from the ECM via CAN. If the information sent using these 2 methods is inconsistent, these DTCs will be stored.

The power management control ECU receives shift position information from 2 sources. It receives a shift position P signal from the shift lock control unit assembly via a direct line, and shift position information from the ECM via CAN. If the information from these 2 sources is inconsistent, this DTC will be stored.

The power management control ECU receives shift position information from 2 sources. It receives a shift position P signal from the shift lock control unit assembly via a direct line, and shift position information from the ECM via CAN. If the information from these 2 sources is inconsistent, this DTC will be stored.

1. ENGINE START SYSTEM FUNCTION If the engine switch is pressed with the shift lever in P or N and the brake pedal depressed, the power management control ECU determines that this is an engine start request. The certification ECU (smart key ECU assembly) and other ECUs perform key verification via LIN communication. The power management control ECU activates the ACC relay. The power management control ECU activates the IG1 NO. 1, IG1 NO. 2, IG1 NO. 3, ACC1, ACC2, IG1 and IG2 relays. The certification ECU (smart key ECU assembly) outputs a steering UNLOCK signal. The signal is sent to the power management control ECU via the steering lock ECU. The power management control ECU activates the starter relay. HINT: When the power management ECU operates the starter relay, it performs cranking holding control. The power management control ECU deactivates the ACC relay until the power management control ECU detects an engine start. HINT: Whether the engine has started is judged based on the engine speed signals sent from the ECM.

When the engine switch is pushed with the electrical key in the cabin, the power management control ECU receives signals to change the power source mode.

HINT

To allow use of the Techstream to inspect the push-button start function when the power source mode is off, repeat opening and closing any of the doors. Opening and closing a door establishes communication between the Techstream and the power management control ECU. (Opening and closing a door can also be simulated by operating a door courtesy light switch.)

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1. CHECK DTC Connect the Techstream to the DLC3. Turn the Techstream on. Turn on and off any of the door courtesy light switches repeatedly at 1.5-second intervals or less until communication between the Techstream and vehicle starts. Enter the following menus: Body Electrical / All ECUs / Health Check. Clear the DTC. Check for DTCs again. OK DTCs are not output. NG --> GO TO DIAGNOSTIC TROUBLE CODE CHART «DIAGNOSTIC TROUBLE CODE CHART»(ref-400834-S03841674552011051800000) OK: Go to next step
2. CHECK SMART ACCESS SYSTEM WITH PUSH-BUTTON START Remove the battery of the electrical key transmitter. Refer to «REMOVAL»(ref-400923-S21443914532011051800000) . Touch the logo side mark of the key or card key to the engine switch. Check that the engine switch can be turned on (IG). OK Power source mode can be changed. NG --> See step 8 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (BATTERY - POWER MANAGEMENT CONTROL ECU) See step 1 NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - POWER MANAGEMENT CONTROL ECU) OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - BODY GROUND) See step 2 NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - BODY GROUND) OK: Go to next step
5. READ VALUE USING TECHSTREAM Reconnect the F8 connector to the power management control ECU. Enter the following menus: Body Electrical / Power Source Control / Data List. Read the Data List according to the display on the Techstream. POWER SOURCE CONTROL Tester Display Measurement Item/Range Normal Condition Diagnostic Note Start Switch1 Start switch 1/ON or OFF ON: Engine switch pushed OFF: Engine switch not pushed - Start Switch2 Start switch 2/ON or OFF ON: Engine switch pushed OFF: Engine switch not pushed - OK ON (engine switch is pushed) and OFF (engine switch is not pushed) appear on the screen. NG --> See step 6 OK --> See step 9
6. INSPECT ENGINE SWITCH Remove the engine switch. Refer to «REMOVAL»(ref-400787-S29218805132011051800000) . Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 7 (SS1) - 5 (GND) Pushed Below 1 ohms 2 (SS2) - 5 (GND) Pushed Below 1 ohms 7 (SS1) - 5 (GND) Not pushed 10 kohms or higher 2 (SS2) - 5 (GND) Not pushed 10 kohms or higher TEXT IN ILLUSTRATION *1 Component without harness connected (Engine Switch) NG --> See step 10 OK: Go to next step
7. CHECK HARNESS AND CONNECTOR (ENGINE SWITCH - POWER MANAGEMENT CONTROL ECU AND BODY GROUND) Disconnect the F8 connector from the power management control ECU. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition F22-7 (SS1) - F8-18 (SSW1) Always Below 1 ohms F22-7 (SS1) - Body ground Always 10 kohms or higher F22-2 (SS2) - F8-17 (SSW2) Always Below 1 ohms F22-2 (SS2) - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *1 Front view of wire harness connector (to Engine Switch) *2 Front view of wire harness connector (to Power Management Control ECU) NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE SWITCH - POWER MANAGEMENT CONTROL ECU OR BODY GROUND) OK --> See step 11
8. GO TO OTHER FLOW CHART (ROOM OSCILLATOR DOES NOT RECOGNIZE KEY). Refer to «Room Oscillator does not Recognize Key»(ref-400940-S05465076302011051800000)
9. REPLACE POWER MANAGEMENT CONTROL ECU. Refer to «REMOVAL»(ref-400866-S34409136982011051800000)
10. REPLACE ENGINE SWITCH. Refer to «REMOVAL»(ref-400787-S29218805132011051800000)
11. REPLACE POWER MANAGEMENT CONTROL ECU. Refer to «REMOVAL»(ref-400866-S34409136982011051800000)

When the engine switch is pushed with the electrical key in the cabin, the power management control ECU receives signals to change the power source mode.

HINT

To allow use of the Techstream to inspect the push-button start function when the power source mode is off, repeat opening and closing any of the doors. Opening and closing a door establishes communication between the Techstream and the power management control ECU. (Opening and closing a door can also be simulated by operating a door courtesy light switch.)

When the engine switch is pushed with the electrical key in the cabin, the power management control ECU receives signals to change the power source mode.

HINT

To allow use of the Techstream to inspect the push-button start function when the power source mode is off, repeat opening and closing any of the doors. Opening and closing a door establishes communication between the Techstream and the power management control ECU. (Opening and closing a door can also be simulated by operating a door courtesy light switch.)

When the engine switch is pushed with the electrical key in the cabin, the power management control ECU receives signals to change the power source mode.

HINT

To allow use of the Techstream to inspect the push-button start function when the power source mode is off, repeat opening and closing any of the doors. Opening and closing a door establishes communication between the Techstream and the power management control ECU. (Opening and closing a door can also be simulated by operating a door courtesy light switch.)

When the engine switch is pushed with the electrical key in the cabin, the power management control ECU receives signals to change the power source mode.

HINT

To allow use of the Techstream to inspect the push-button start function when the power source mode is off, repeat opening and closing any of the doors. Opening and closing a door establishes communication between the Techstream and the power management control ECU. (Opening and closing a door can also be simulated by operating a door courtesy light switch.)

When the engine switch is pushed with the electrical key in the cabin, the power management control ECU receives signals to change the power source mode.

HINT

To allow use of the Techstream to inspect the push-button start function when the power source mode is off, repeat opening and closing any of the doors. Opening and closing a door establishes communication between the Techstream and the power management control ECU. (Opening and closing a door can also be simulated by operating a door courtesy light switch.)