Suspension Control: Other Lexus LS IV

PRECAUTION

1. NOTICE FOR INITIALIZATION NOTE: When disconnecting the cable from the negative (-) battery terminal, initialize the following system after the cable is reconnected. SYSTEM NAME REFERENCE CHART System Name See procedure Navigation System (for DVD) «INITIALIZATION»(ref-349706-S07943075812009120800000) Advanced Parking Guidance System Power Trunk Lid System Rear Door Sunshade System
2. AIR SUSPENSION SYSTEM PRECAUTION NOTE: If the vehicle is raised with the engine running, connect terminals 11 (OPA) and 4 (CG) of the DLC3 to stop the vehicle height control operation of the suspension control ECU. Do not operate the steering wheel if there is no air in the pneumatic cylinder. The pneumatic cylinder could be damaged if twisted without air in the cylinder. When lowering the vehicle without air in the cylinder, make sure all the pipes are securely connected. The pneumatic cylinder could be damaged if any pipe is disconnected while lowering the vehicle. Do not apply battery voltage to the compressor motor for more than 60 seconds to prevent damage to the motor. When it is necessary to perform the operation by charging the battery for more than 60 seconds (for example, height recovery without air in the cylinder), proceed to the operation as follows: after 60 seconds have passed, turn the engine switch off once, and then turn the engine switch on (IG) again to commence with the operation. Do not operate the height control compressor continuously for 3 minutes or more. If operated continuously for 3 minutes, do not operate it for 10 minutes or more. If operated continuously for 3 minutes or more, operation automatically stops and DTC C1761 is output. Performing work after replacing the suspension control ECU with a normally functioning one from another vehicle may result in DTCs being stored, or have a negative effect on other systems. When replacing the suspension control ECU, be sure to install a new one.

Scheme 140

Scheme 141

Scheme 142

Scheme 143

Scheme 144

TERMINALS OF ECU

HINT

Inspect the connectors from the back side while the connectors are connected.

Scheme 145

1. CHECK SUSPENSION CONTROL ECU TERMINAL DESCRIPTION CHART Terminal No. (Symbols) Wiring Color Terminal Description Condition Specified Condition L88-1 (B) - L88-4 (GND) W - W-B IG power supply Engine switch on (IG) 10 to 14 V L88-4 (GND) - Body ground W-B - Body ground Ground Always Below 1 ohms L88-5 (SLEX) - L88-4 (GND) L-W-B Exhaust valve Engine switch on (IG) Below 1 V Engine idling, height control switch from "HEIGHT HIGH" to normal 8 V or more L88-6 (RC) - L88-4 (GND) BE - W-B Suspension control relay Engine switch on (IG) Below 1 V Engine idling, height control switch from normal to "HEIGHT HIGH" during compressor operation 8 V or more L88-7 (CANH) - L88-8 (CANL) B-W CAN communication line Engine switch off 54 to 69 ohms L88-14 (TD) - L88-4 (GND) BE - W-B Height control is not operating Engine switch on (IG) 10 to 14 V L88-16 (SLFR) - L88-4 (GND) R - W-B Height control valve (for Front RH) Engine switch on (IG) Below 1 V Engine idling, height control switch from normal to "HEIGHT HIGH" or reverse 8 V or more L88-17 (SLFL) - L88-4 (GND) W - W-B Height control valve (for Front LH) Engine switch on (IG) Below 1 V Engine idling, height control switch from normal to "HEIGHT HIGH" or reverse 8 V or more L88-18 (SBL1) - L88-4 (GND) R - W-B Height control sensor power source (for Front LH) Engine switch on (IG) 4.5 to 5.5 V L88-20 (SBR1) - L88-4 (GND) V - W-B Height control sensor power source (for Front RH) Engine switch on (IG) 4.5 to 5.5 V L88-21 (SGR1) - L88-4 (GND) R - W-B Height control sensor ground (for Front RH) Always Below 1 ohms L88-22 (SGL1) - L88-4 (GND) LG - W-B Height control sensor ground (for Front LH) Always Below 1 ohms L88-25 (SLRL) - L88-4 (GND) G - W-B Height control valve (for Rear LH) Engine switch on (IG) Below 1 V L88-25 (SLRL) - L88-4 (GND) G - W-B Height control valve (for Rear LH) Engine idling, height control switch from normal to "HEIGHT HIGH" or reverse 8 V or more L88-26 (SLRR) - L88-4 (GND) Y - W-B Height control valve (for Rear RH) Engine switch on (IG) Below 1 V Engine idling, height control switch from normal to "HEIGHT HIGH" or reverse 8 V or more A39-3 (FBR+) - L88-4 (GND) R - W-B Suspension control actuator (for Front RH) Engine switch off 12.0 to 12.8 ohms A39-4 (FBR-) - L88-4 (GND) LG - W-B Suspension control actuator (for Front RH) Engine switch off 12.0 to 12.8 ohms A39-9 (FAR+) - L88-4 (GND) BE - W-B Suspension control actuator (for Front RH) Engine switch off 12.0 to 12.8 ohms A39-11 (FAR-) - L88-4 (GND) R - W-B Suspension control actuator (for Front RH) Engine switch off 12.0 to 12.8 ohms A39-13 (FAL+) - L88-4 (GND) L - W-B Suspension control actuator (for Front LH) Engine switch off 12.0 to 12.8 ohms A39-14 (FAL-) - L88-4 (GND) R - W-B Suspension control actuator (for Front LH) Engine switch off 12.0 to 12.8 ohms A39-15 (FBL+) - L88-4 (GND) W - W-B Suspension control actuator (for Front LH) Engine switch off 12.0 to 12.8 ohms A39-16 (FBL-) - L88-4 (GND) BE - W-B Suspension control actuator (for Front LH) Engine switch off 12.0 to 12.8 ohms A39-17 (RM+) - L88-4 (GND) Y - W-B Motor lock (+) Engine idling, height control switch from normal to "HEIGHT HIGH" during compressor operation Below 1 V Engine idling, height control compressor not operating 8 V OR higher A39-18 (RM-) - L88-4 (GND) B - W-B Motor lock (-) Always Below 1 ohms A39-19 (SHR2) - L88-4 (GND) LG - W-B Height control sensor (for rear LH) Engine switch on (IG) 0.5 to 4.5 V Engine switch on (IG) Engine idling, completion of vehicle height control from "HEIGHT HIGH" to normal Approx. 2.5 V A39-20 (SHFR) - L88-4 (GND) B - W-B Height control sensor (for Front RH) Engine switch on (IG) 0.5 to 4.5 V Engine idling, completion of vehicle height control from "HEIGHT HIGH" to normal Approx. 2.5 V A39-21 (SHF2) - L88-4 (GND) L - W-B Height control sensor (for Front LH) Engine switch on (IG) 0.5 to 4.5 V Engine idling, completion of vehicle height control from "HEIGHT HIGH" to normal Approx. 2.5 V A39-22 (SHFL) - L88-4 (GND) L - W-B Height control sensor (for Front LH) Engine switch on (IG) 0.5 to 4.5 V Engine idling, completion of vehicle height control from "HEIGHT HIGH" to normal Approx. 2.5 V A39-23 (SBL3) - L88-4 (GND) BR - W-B Height control sensor power source (for AFS ECU) Engine switch on (IG) 4.5 to 5.5 V A39-24 (SGL3) - L88-4 (GND) GR - W-B Height control sensor ground (for AFS ECU) Always Below 1 ohms R1-3 (RAR-) - L88-4 (GND) G - W-B Suspension control actuator (for Rear RH) Engine switch off 12.0 to 12.8 ohms R1-4 (RBR+) - L88-4 (GND) LG - W-B Suspension control actuator (for Rear RH) Engine switch off 12.0 to 12.8 ohms R1-5 (RBR-) - L88-4 (GND) P - W-B Suspension control actuator (for Rear RH) Engine switch off 12.0 to 12.8 ohms R1-6 (RAL+) - L88-4 (GND) L - W-B Suspension control actuator (for Rear LH) Engine switch off 12.0 to 12.8 ohms R1-7 (RAL-) - L88-4 (GND) G - W-B Suspension control actuator (for Rear LH) Engine switch off 12.0 to 12.8 ohms R1-8 (RBL+) - L88-4 (GND) BE - W-B Suspension control actuator (for Rear LH) Engine switch off 12.0 to 12.8 ohms R1-11 (SGFL) - L88-4 (GND) L - W-B Acceleration sensor (for Front LH) Engine switch on (IG), keep the vehicle still without any vertical movement for 1 second Approx. 2.5 V R1-12 (SGR3) - L88-4 (GND) LG - W-B Acceleration sensor ground (for Rear) Always Below 1 ohms R1-13 (RAR+) - L88-4 (GND) Y - W-B Suspension control actuator (for Rear RH) Engine switch off 12.0 to 12.8 ohms R1-15 (SBR3) - L88-4 (GND) BE - W-B Acceleration sensor power source (for Rear) Engine switch on (IG) 4.5 to 5.5 V R1-16 (SBL) - L88-4 (GND) R - W-B Acceleration sensor power source (for Front LH) Engine switch on (IG) 4.5 to 5.5 V R1-20 (RBL-) - L88-4 (GND) BR - W-B Suspension control actuator (for Rear LH) Engine switch off 12.0 to 12.8 ohms R1-21 (CA2L) - R1-22 (CA2H) W - B CAN communication line Engine switch off 54 to 69 ohms R1-23 (SGL2) - L88-4 (GND) GR - W-B Height control sensor ground (for Rear LH) Always Below 1 ohms R1-24 (SBL2) - L88-4 (GND) BR - W-B Height control sensor power source (for Rear LH) Engine switch on (IG) 4.5 to 5.5 V R1-25 (SGR2) - L88-4 (GND) V - W-B Height control sensor ground (for Rear RH) Always Below 1 ohms R1-26 (SBR2) - L88-4 (GND) B - W-B Height control sensor power source (for Rear RH) Engine switch on (IG) 4.5 to 5.5 V R1-27 (SGRR) - L88-4 (GND) BR - W-B Acceleration sensor (for Rear) Engine switch on (IG), keep the vehicle still without any vertical movement for 1 second Approx. 2.5 V R1-28 (SHRR) - L88-4 (GND) P - W-B Height control sensor (for Rear RH) Engine switch on (IG) 0.5 to 4.5 V Engine idling, completion of vehicle height control from "HEIGHT HIGH" to normal Approx. 2.5 V R1-29 (SGL) - L88-4 (GND) V - W-B Acceleration sensor ground (for Front LH) Always Below 1 ohms R1-30 (SHRL) - L88-4 (GND) LG - W-B Height control sensor (for Rear LH) Engine switch on (IG) 0.5 to 4.5 V Engine idling, completion of vehicle height control from "HEIGHT HIGH" to normal Approx. 2.5 V

Scheme 146

Scheme 147

1. DIAGNOSIS SYSTEM Indicator light If a malfunction is detected in the vehicle height control function, the following occurs: 1) The "HEIGHT HIGH" indicator light blinks at 1 second intervals, the master warning light illuminates, and "Check Air Suspension System" is displayed on the multi-information display. DTCs (Normal mode) DTCs are memorized in the suspension control ECU and read by using the Techstream. Refer to the DTC check procedure (see «DTC CHECK/CLEAR»(ref-349750-S00565012962009120800000) ). Test mode By switching from normal mode into test mode, you can inspect the front acceleration sensor and rear acceleration sensor (see «TEST MODE PROCEDURE»(ref-349750-S19987600632009120800000) ).
2. CHECK INDICATOR LIGHT Turn the engine switch on (IG). Check that the height control indicator light (HEIGHT HIGH) and absorber control indicator light (SPORT and COMFORT) comes on for 2 seconds. If the indicator check result is not normal, proceed to troubleshooting for the indicator light circuit. TROUBLE AREA CHART Trouble Area See procedure Indicator circuit «INDICATOR CIRCUIT»(ref-349750-S06563200772009120800000)

Scheme 148

1. CHECK DTC Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Enter the following menus: Chassis/Air suspension/Trouble Codes. Read the DTCs by following the prompts on the Techstream screen. HINT: Refer to the Techstream operator's manual for further details. Refer to the " «DIAGNOSTIC TROUBLE CODE CHART»(ref-349750-S02511098542009120800000) " for DTC information .
2. CLEAR DTC HINT: After repairing the malfunctions, clear the DTCs. Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Enter the following menus: Chassis/Air suspension/Trouble Codes. Erase the DTCs by following the prompts on the Techstream screen. HINT: Refer to the Techstream operator's manual for further details.

FAIL-SAFE CHART

1. FAIL-SAFE FUNCTION When an air suspension system malfunction is detected under the normal control operation, the suspension control ECU will suspend the switch control of the height control operation. Air suspension system FAIL-SAFE CHART DTC Chart Malfunction Item Fall-safe Operation Fall-safe Deactivation Conditions C1711 C1712 C1713 C1714 Height control sensor circuit Height control is interrupted, and damping control is performed with the lower step limit of the front and rear absorber control actuator set to 9. Returns to normal condition. C1715 C1716 C1717 Acceleration sensor circuit Damping control is performed with the lower step limit of the front and rear absorber control actuator set to 9. Returns to normal condition. C1731 C1732 C1733 C1734 Absorber control actuator circuit Interrupts damping control, after moving to the 9th step. (Except malfunction actuator) Returns to normal condition. C1741 C1742 C1743 C1744 Height control solenoid valve circuit Interrupts height control. Returns to normal condition. C1745 Exhaust solenoid valve circuit Interrupts height control. Returns to normal condition. C1751 Suspension control relay circuit Interrupts height control. Return to normal condition. C1752 C1761 Lock is powered continuously or powered excessively in height control compressor motor Interrupts height control. Returns to normal condition. C1762 Continuous electric current to exhaust solenoid valve Interrupts height control. Returns to normal condition. C1781 Suspension control ECU When there is an EEPROM malfunction, the vehicle height is fixed at the normal height and damping control is canceled after setting the step of the front and rear absorber control actuator to 9 (height control continues to operate when there is no EEPROM malfunction). Returns to normal condition. C1782 Power source voltage Interrupts height control and damping control. Returns to normal condition. C1783 Vehicle speed sensor circuit Control is canceled after setting the step of the front and rear absorber control actuator to 9. Returns to normal condition. C1784 Steering angle sensor Interrupts damping force of rolling control. Returns to normal condition. C1785 Steering control ECU Interrupts damping force of rolling control. Returns to normal condition. C1787 C1788 Yaw & acceleration sensor Interrupts damping force of rolling control. Returns to normal condition. C1789 CAN communication system ECM Suspension control ECU AFS ECU The vehicle height is fixed at the normal height and damping control is canceled after setting the step of the front and rear absorber control actuator to 9. Returns to normal condition. U0100 U0101 U0124 CAN communication system Continues height control and damping control. Returns to normal condition. U0122 U0132 CAN communication system Control is canceled after setting the step of the front and rear absorber control actuator to 9. Returns to normal condition. U0126 U0130 CAN communication system Interrupt damping force of rolling control. Returns to normal condition.