System Operation Check

WARNING: This page is about a different car, the 2003 Lexus RX 300 and 2002 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.

Trouble shooting of a power seat and/or seat heater system complaint begins with verification of the customer problem. If problem occurs, go to step 3. If problem does not occur, go to next step.
If problem does not occur, review conditions under which problem occurred for customer and try to duplicate those conditions. For example, if the problem occurs on rainy days or during high humidity conditions, sprinkle water onto vehicle and see if malfunction occurs. DO NOT sprinkle water directly into engine compartment or onto electronic components. Visually inspect for signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. Inspect for loose or corroded connections, damaged wiring harness and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary.
Inspect the multiplex communication system and confirm that there is no trouble by the basic inspection and DTC check. See PRE-CHECK under SELF-DIAGNOSTIC in appropriate MULTIPLEX COMMUNICATION SYSTEM article in COMMUNICATION DEVICES.

Determine problem symptom. See PROBLEM SYMPTOM INDEX table.

PROBLEM SYMPTOM INDEX

Symptom

Suspected Area ⁽¹⁾

Power Seat Control System

Power Seat Does Not Operate (Door Lock Does Not Operate)

⁽²⁾⁽³⁾⁽⁴⁾

Power Seat Does Not Operate (Door Lock Is Normal)

⁽²⁾⁽³⁾⁽⁴⁾

Driver's Seat Does Not Operate

⁽³⁾⁽²⁾

Passenger's Seat Does Not Operate

⁽⁴⁾⁽²⁾

Slide Operation Does Not Operate

⁽³⁾⁽⁴⁾⁽²⁾⁽⁵⁾

Front Vertical Operation Does Not Operate

⁽³⁾⁽⁴⁾⁽²⁾⁽⁶⁾

Lifter Operation Does Not Operate

⁽³⁾⁽²⁾⁽⁷⁾

Reclining Operation Does Not Operate

⁽³⁾⁽⁴⁾⁽²⁾⁽⁸⁾

Lumbar Support Operation Does Not Operate

⁽³⁾⁽⁴⁾⁽²⁾⁽⁹⁾

Memory Return Function Does Not Operate

⁽¹⁰⁾⁽¹¹⁾

Memory Return Function Operates Abnormally

⁽¹²⁾⁽¹¹⁾

Seat Heater System

Seat Heaters Do Not Operate (Driver's & Passenger's)

⁽¹³⁾⁽¹⁴⁾⁽¹⁵⁾⁽²⁾⁽¹⁶⁾

Driver's Or Passenger's Seat Heater Does Not Operate

⁽¹⁵⁾⁽²⁾

Seat Heater Temperature Is Too Hot

⁽¹⁶⁾

⁽¹⁾	Perform test procedures in order listed under suspected area.

⁽²⁾	Check the wiring harness.

⁽³⁾	Check the driver's power seat switch. See POWER SEAT SWITCH (DRIVER) under COMPONENT TESTS.

⁽⁴⁾	Check the passenger's power seat switch. See POWER SEAT SWITCH (PASSENGER) under COMPONENT TESTS.

⁽⁵⁾	Check the slide motor. See POWER SEAT MOTOR (SLIDE, FRONT VERTICAL, LIFTER & RECLINING) under COMPONENT TESTS.

⁽⁶⁾	Check the front vertical motor. See POWER SEAT MOTOR (SLIDE, FRONT VERTICAL, LIFTER & RECLINING) under COMPONENT TESTS.

⁽⁷⁾	Check the lifter motor. See POWER SEAT MOTOR (SLIDE, FRONT VERTICAL, LIFTER & RECLINING) under COMPONENT TESTS.

⁽⁸⁾	Check the reclining motor. See POWER SEAT MOTOR (SLIDE, FRONT VERTICAL, LIFTER & RECLINING) under COMPONENT TESTS.

⁽⁹⁾	Check the lumbar support motor. See LUMBAR SUPPORT MOTOR under COMPONENT TESTS.

⁽¹⁰⁾	Check the M1, M2 SET switch circuit. See M1, M2 SET SWITCH CIRCUIT under CIRCUIT TESTS.

⁽¹¹⁾	Check the power seat position ECU.

⁽¹²⁾	Check the seat position sensor circuit. See POSITION SENSOR CIRCUIT under CIRCUIT TESTS.

⁽¹³⁾	Check the SEAT HTR fuse located in the instrument panel junction block.

⁽¹⁴⁾	Check the engine main relay located in the relay block No. 1.

⁽¹⁵⁾	Check the seat heater switch. See SEAT HEATER SWITCH under COMPONENT TESTS.

⁽¹⁶⁾	Check the seat heater. See SEAT HEATER BACK and SEAT HEATER CUSHION under COMPONENT TESTS.

Inspect the circuits of the power seat and seat heater systems. See CIRCUIT TESTS . If the trouble still reappears in the power seat system, even though there are no abnormalities in any of the other circuits, check and replace the power seat position ECU as the last step.
After repairs have been completed, confirm that problem has been eliminated. Operate the system under same conditions recorded for original complaint. If problem is no longer present, repair has corrected problem. If problem is still present, further diagnosis and repair is required.