Lexus IS250 IS220d GSE20 ALE20 - SEAT
READ VALUE OF INTELLIGENT TESTER (SEAT MEMORY SWITCH)
CHECK HARNESS AND CONNECTOR (SEAT MEMORY SWITCH CIRCUIT)
CHECK HARNESS AND CONNECTOR (OUTER MIRROR CONTROL ECU - SEAT MEMORY SWITCH, BODY GROUND)
FRONT POWER SEAT CONTROL SYSTEM (w/ Seat Position Memory System) - Driver Side Seat Memory Switch Circuit
DESCRIPTION
The driver side seat memory switch sends signals to the driver side outer mirror control ECU via the multiplex communication system to memorize a given seat position. This memory system does not use a position sensor. The seat position is detected by counting pulses that are output when the motor turns. If there is no pulse output from the motor, the motor will stop operating. The driver side seat memory switch is later used to send signals to the front power seat switch (position control ECU) to return the seat to one of the memorized positions.
The power seat memory switch operation can be performed only when the engine switch is on (IG) and the shift lever is in the P position.
The power seat memory switch operation can be performed only when the engine switch is on (IG), apply the parking brake, and seat the vehicle speed below 3 km/h (1.9 mph).
WIRING DIAGRAM
INSPECTION PROCEDURE
1.READ VALUE OF INTELLIGENT TESTER (SEAT MEMORY SWITCH) |
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Read the DATA LIST.
Item | Measurement Item/Range (Display) | Normal Condition | Diagnostic Note |
Seat Memory No. 1 | M1 switch signal / ON or OFF | ON: M1 switch is ON OFF: M1 switch is OFF | - |
Seat Memory No. 2 | M2 switch signal / ON or OFF | ON: M2 switch is ON OFF: M2 switch is OFF | - |
Seat Memory No. 3 | M3 switch signal / ON or OFF | ON: M3 switch is ON OFF: M3 switch is OFF | - |
Seat SET Switch | SET switch signal / ON or OFF | ON: SET switch is ON OFF: SET switch is OFF | - |
- OK:
- On the tester screen, each item changes between ON and OFF according to the above chart.
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OK | ||
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2.INSPECT SEAT MEMORY SWITCH |
Remove the seat memory switch.

LHD
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Switch Position Specified Condition 1 (MRY) - 5 E) SET switch is pressed Below 1 Ω 2 (M1) - 5 (E) M1 switch is pressed Below 1 Ω 3 (M2) - 5 (E) M2 switch is pressed Below 1 Ω 4 (M3) - 5 (E) M3 switch is pressed Below 1 Ω 1 (MRY) - 5 E) SET switch is not pressed 10 kΩ or higher 2 (M1) - 5 (E) M1 switch is not pressed 10 kΩ or higher 3 (M2) - 5 (E) M2 switch is not pressed 10 kΩ or higher 4 (M3) - 5 (E) M3 switch is not pressed 10 kΩ or higher

RHD
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Switch Position Specified Condition 1 (MMRY) - 5 E) SET switch is pressed Below 1 Ω 2 (1) - 5 (E) M1 switch is pressed Below 1 Ω 3 (2) - 5 (E) M2 switch is pressed Below 1 Ω 4 (3) - 5 (E) M3 switch is pressed Below 1 Ω 1 (MMRY) - 5 E) SET switch is not pressed 10 kΩ or higher 2 (1) - 5 (E) M1 switch is not pressed 10 kΩ or higher 3 (2) - 5 (E) M2 switch is not pressed 10 kΩ or higher 4 (3) - 5 (E) SET switch is not pressed 10 kΩ or higher
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OK | ||
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4.CHECK HARNESS AND CONNECTOR (OUTER MIRROR CONTROL ECU - SEAT MEMORY SWITCH, BODY GROUND) |

LHD
Disconnect the outer mirror control ECU LH connector.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Specified Condition M10-22 (M1) - M6-2 (M1) Below 1 Ω M10-23 (M2) - M6-3 (M2) Below 1 Ω M10-24 (M3) - M6-4 (M3) Below 1 Ω M10-25 (MM) - M6-1 (MM) Below 1 Ω M10-26 (MSWE) - M6-5 (E) Below 1 Ω M10-26 (MSWE) - Body ground Below 1 Ω M6-5 (E) - Body ground Below 1 Ω

RHD
Disconnect the outer mirror control ECU RH connector.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Specified Condition L10-22 (M1) - L7-2 (M1) Below 1 Ω L10-23 (M2) - L7-3 (M2) Below 1 Ω L10-24 (M3) - L7-4 (M3) Below 1 Ω L10-25 (MM) - L7-1 (MM) Below 1 Ω L10-26 (MSWE) - L7-5 (E) Below 1 Ω L10-26 (MSWE) - Body ground Below 1 Ω L7-5 (E) - Body ground Below 1 Ω
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OK | ||
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