Body Electrical. Lexus Is250, Is220D. Gse20 Ale20
Lighting. Lexus Is250, Is220D. Gse20 Ale20
Lighting System -- Terminals Of Ecu |
CHECK ENGINE ROOM NO. 2 R/B (FRONT CONTROLLER) |

Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition |
ALTB (2E-1) - Body ground | W - Body ground | Power source circuit | Always | 10 to 14 V |
BATB (2E-2) - Body ground | W-L - Body ground | Power source circuit | Always | 10 to 14 V |
FMIG (2E-3) - Body ground | B-Y - Body ground | Engine switch signal circuit | Engine switch on (IG) | 10 to 14 V |
FMIG (2E-3) - Body ground | B-Y - Body ground | Engine switch signal circuit | Engine switch off | Below 1 V |
FMB3 (2E-4) - Body ground | G-R - Body ground | Power source circuit | Always | 10 to 14 V |
E (2F-1) - Body ground | W-B - Body ground | Ground | Always | Below 1 V |
MPX1 (2F-5) - Body ground | L - Body ground | Multiplex communication signal circuit | Engine switch on (IG) | Signal waveform |
MPX2 (2F-6) - Body ground | GR - Body ground | Multiplex communication signal circuit | Engine switch on (IG) | Signal waveform |
FOGR (2G-6) - Body ground | LG - Body ground | Fog light circuit (To front fog light RH) | Front fog light ON | 10 to 14 V |
FOGR (2G-6) - Body ground | LG - Body ground | Fog light circuit (To front fog light RH) | Front fog light OFF | Below 1 V |
FOGL (2G-7) - Body ground | G-R - Body ground | Fog light circuit (To front fog light LH) | Front fog light ON | 10 to 14 V |
FOGL (2G-7) - Body ground | G-R - Body ground | Fog light circuit (To front fog light LH) | Front fog light OFF | Below 1 V |
CRAR (2G-8) - Body ground | G - Body ground | Taillight circuit (To parking light RH) | Light control switch in TAIL | 10 to 14 V |
CRAR (2G-8) - Body ground | G - Body ground | Taillight circuit (To parking light RH) | Light control switch OFF | Below 1 V |
CRAL (2G-9) - Body ground | G - Body ground | Taillight circuit (To parking light LH) | Light control switch in TAIL | 10 to 14 V |
CRAL (2G-9) - Body ground | G - Body ground | Taillight circuit (To parking light LH) | Light control switch OFF | Below 1 V |
HLHR (2G-12) - Body ground | R-W - Body ground | Hi-beam circuit (To headlight RH) | Headlight dimmer switch in HI | 10 to 14 V |
HLHR (2G-12) - Body ground | R-W - Body ground | Hi-beam circuit (To headlight RH) | Headlight dimmer switch in HEAD | Below 1 V |
HLHL (2G-13) - Body ground | R-Y - Body ground | Hi-beam circuit (To headlight LH) | Headlight dimmer switch in HI | 10 to 14 V |
HLHL (2G-13) - Body ground | R-Y - Body ground | Hi-beam circuit (To headlight LH) | Headlight dimmer switch in HEAD | Below 1 V |
(2G-4) - Body ground | R-L - Body ground | Hi-beam circuit | Headlight dimmer switch in HI | 10 to 14 V |
(2G-4) - Body ground | R-L - Body ground | Hi-beam circuit | Headlight dimmer switch in HEAD | Below 1 V |
(2G-10) - Body ground | G-Y - Body ground | Taillight circuit (To marker light RH) | Light control switch in TAIL | 10 to 14 V |
(2G-10) - Body ground | G-Y - Body ground | Taillight circuit (To marker light RH) | Light control switch OFF | Below 1 V |
(2G-11) - Body ground | BR - Body ground | Taillight circuit (To marker light LH) | Light control switch in TAIL | 10 to 14 V |
(2G-11) - Body ground | BR - Body ground | Taillight circuit (To marker light LH) | Light control switch OFF | Below 1 V |
CHECK MAIN BODY ECU RH (COWL SIDE J/B RH) |

Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition |
GND2 (RD-7) - Body ground | W-B - Body ground | Ground | Always | Below 1 V |
LCTY (RA-11) - Body ground | BR - Body ground | Illumination signal (From door courtesy switch rear LH) | Rear LH door is closed | 10 to 14 V |
LCTY (RA-11) - Body ground | BR - Body ground | Illumination signal (From door courtesy switch rear LH) | Rear LH door is open | Below 1 V |
MPX1 (RJ-21) - Body ground | GR - Body ground | Multiplex communication signal circuit | Engine switch on (IG) | Signal waveform |
BECU (RK-5) - Body ground | G-R - Body ground | Multiplex communication power source circuit | Always | 10 to 14 V |
HRLY (RL-7) - Body ground | R-W - Body ground | HEAD signal (To HEAD relay) | Light control switch OFF or in TAIL | 10 to 14 V |
HRLY (RL-7) - Body ground | R-W - Body ground | HEAD signal (To HEAD relay) | Light control switch in HEAD | Below 1 V |
DCTY (P1-14) - Body ground | W - Body ground | Illumination signal (From driver side courtesy switch) | Driver's side door is closed | 10 to 14 V |
DCTY (P1-14) - Body ground | W - Body ground | Illumination signal (From driver side courtesy switch) | Driver's side door is open | Below 1 V |
RCTY (P1-16) - Body ground | O - Body ground | Illumination signal (From door courtesy switch rear RH) | Rear door RH is closed | 10 to 14 V |
RCTY (P1-16) - Body ground | O - Body ground | Illumination signal (From door courtesy switch rear RH) | Rear door RH is open | Below 1 V |
FSPT (J75-15) - Body ground | R - Body ground | Illumination signal (To footwell lights) | Footwell lights come on | Below 1 V |
FSPT (J75-15) - Body ground | R - Body ground | Illumination signal (To footwell lights) | Footwell lights go off | 10 to 14 V |
MPX2 (J75-21) - Body ground | GR - Body ground | Multiplex communication signal circuit | Engine switch on (IG) | Signal waveform |
CLTE (J74-4) - Body ground | W - Body ground | Automatic light control sensor ground circuit | Always | Below 1 V |
CLTS (J74-5) - Body ground | R - Body ground | Automatic light control sensor ground circuit | Engine switch off | Below 1 V |
CLTS (J74-5) - Body ground | R - Body ground | Automatic light control sensor ground circuit | Engine switch on (IG), light control switch in AUTO, headlights come ON | Signal waveform |
CLTB (J74-6) - Body ground | GR - Body ground | Automatic light control sensor power source circuit | Engine switch off | Below 1 V |
CLTB (J74-6) - Body ground | GR - Body ground | Automatic light control sensor power source circuit | Engine switch on (IG) | 10 to 14 V |
HEAD (J74-23) - Body ground | L - Body ground | HEAD signal (From light control switch) | Light control switch OFF or in TAIL | 10 to 14 V |
HEAD (J74-23) - Body ground | L - Body ground | HEAD signal (From light control switch) | Light control switch in HEAD | Below 1 V |
ALTB (RA-15) - Body ground | SB - Body ground | Power source circuit | Always | 10 to 14 V |
UL2 (J75-4) - Body ground | O - Body ground | Interior light switch (ON / OFF) signal | Interior light switch ON | Below 1 V |
UL2 (J75-4) - Body ground | O - Body ground | Interior light switch (ON / OFF) signal | Interior light switch OFF | 10 to 14 V |
TRLY (RD-1) - Body ground | Y - Body ground | HEAD signal (to HEAD relay) | Light control switch OFF | 10 to 14 V |
TRLY (RD-1) - Body ground | Y - Body ground | HEAD signal (to HEAD relay) | Light control switch in TAIL | Below 1 V |
PCYL (J75-24) - Body ground | G - Body ground | Illumination signal (From door courtesy light front LH) | Passenger's side door is open | Below 1 V |
PCYL (J75-24) - Body ground | G - Body ground | Illumination signal (From door courtesy light front LH) | Passenger's side door is closed | 10 to 14 V |
DCYL (P1-13) - Body ground | G - Body ground | Illumination signal (From door courtesy light front RH) | Driver's side door is open | Below 1 V |
DCYL (P1-13) - Body ground | G - Body ground | Illumination signal (From door courtesy light front RH) | Driver's side door is closed | 10 to 14 V |
LGCY (J75-25) - Body ground | L - Body ground | Illumination signal (From luggage door courtesy switch) | Luggage door is open | Below 1 V |
LGCY (J75-25) - Body ground | L - Body ground | Illumination signal (From luggage door courtesy switch) | Luggage door is closed | 10 to 14 V |
PCTY (J75-23) - Body ground | B - Body ground | Illumination signal (From door courtesy switch front LH) | Passenger's side door is open | Below 1 V |
PCTY (J75-23) - Body ground | B - Body ground | Illumination signal (From door courtesy switch front LH) | Passenger's side door is closed | 10 to 14 V |
HAZ (J74-2) - Body ground | Y - Body ground | HAZARD signal (From HAZARD switch) | HAZARD switch ON | Below 1 V |
HAZ (J74-2) - Body ground | Y - Body ground | HAZARD signal (From HAZARD switch) | HAZARD switch OFF | 10 to 14 V |
CHECK MAIN BODY ECU LH |

Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition |
GND (LD-3) - Body ground | W-B - Body ground | Ground | Always | Below 1 V |
TR (LA-15) - Body ground | P - Body ground | RH side turn signal (To turn signal flasher assembly) | Engine switch off | Below 1 V |
TR (LA-15) - Body ground | P - Body ground | RH side turn signal (To turn signal flasher assembly) | Engine switch on (IG) and turn signal switch (right turn) on | 10 to 14 V (60 to 120 times per minute) |
TL (LA-16) - Body ground | BR - Body ground | LH side turn signal (To turn signal flasher assembly) | Engine switch off | Below 1 V |
TL (LA-16) - Body ground | BR - Body ground | LH side turn signal (To turn signal flasher assembly) | Engine switch on (IG) and turn signal switch (left turn) on | 10 to 14 V (60 to 120 times per minute) |
SGND (LD-8) - Body ground | W-B - Body ground | Ground | Always | Below 1 V |
SGND (LD-9) - Body ground | W-B - Body ground | Ground | Always | Below 1 V |
MPXB (LD-18) - Body ground | LG - Body ground | Multiplex communication power source circuit | Always | 10 to 14 V |
ILE (A36-2) - Body ground | V - Body ground | Illumination signal (To front interior light) | Interior light switch in DOOR position and interior lights come on | Below 1 V |
ILE (A36-2) - Body ground | V - Body ground | Illumination signal (To front interior light) | Interior light switch in DOOR position and interior lights go off | 10 to 14 V |
RCTY (Q1-3) - Body ground | R - Body ground | Illumination signal (To shift illumination light rear RH) | Shift illumination comes on | Below 1 V |
RCTY (Q1-3) - Body ground | R - Body ground | Illumination signal (To shift illumination light rear RH) | Shift illumination goes off | 10 to 14 V |
LCTY (Q1-4) - Body ground | LG - Body ground | Illumination signal (To door mirror foot lights) | Door mirror foot light comes on | 10 to 14 V |
MPX1 (Q3-15) - Body ground | GR - Body ground | Multiplex communication signal circuit | Engine switch on (IG) | Signal waveform |
RFRL (LJ-25) - Body ground | O - Body ground | RR Foglight signal (to RR Foglight) | RR foglight switch off | 10 to 14 V |
RFRL (LJ-25) - Body ground | O - Body ground | RR Foglight signal (to RR Foglight) | RR foglight switch on | Below 1 V |
MPX2 (A30-17) - Body ground | GR - Body ground | Multiplex communication signal circuit | Engine switch on (IG) | Signal waveform |
ILE1 (LA-19) - Body ground | W - Body ground | Illumination signal (to scuff plate light) | Room light switch in DOOR position and scuff plate lights come on | Below 1 V |
ILE1 (LA-19) - Body ground | W - Body ground | Illumination signal (to scuff plate light) | Room light switch in DOOR position and scuff plate lights go off | 10 to 14 V |
LGCY (Q3-3) - Body ground | W - Body ground | Illumination signal (to seat illumination) | Seat illumination comes on | Below 1 V |
LGCY (Q3-3) - Body ground | W - Body ground | Illumination signal (to seat illumination) | Seat illumination goes off | 10 to 14 V |
BDCY (Q3-11) - Body ground | P - Body ground | Interior light switch (Door) signal | Interior light switch on | Below 1 V |
BDCY (Q3-11) - Body ground | P - Body ground | Interior light switch (Door) signal | Interior light switch off | 10 to 14 V |
CHECK COMBINATION SWITCH ASSEMBLY (Windshield Wiper Switch) |

Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition |
B (J26-1) - E (J26-5) | LG - W-B | Power source circuit (From battery) | Always | 10 to 14 V |
IG (J26-2) - E (J26-5) | B - W-B | Engine switch signal circuit (From engine switch) | Engine switch off | Below 1 V |
IG (J26-2) - E (J26-5) | B - W-B | Engine switch signal circuit (From engine switch) | Engine switch on (IG) | 10 to 14 V |
HEAD (J26-4) - Body ground | L - Body ground | Light control switch HEAD signal | Light control switch not in HEAD | 10 to 14 V |
HEAD (J26-4) - Body ground | L - Body ground | Light control switch HEAD signal | Light control switch in HEAD | Below 1 V |
E (J26-5) - Body ground | W-B - Body ground | Ground | Always | Below 1 V |
MPX1 (J26-6) - Body ground | GR - Body ground | Multiplex communication signal circuit | Engine switch on (IG) | Signal waveform |
MPX2 (J26-7) - Body ground | GR - Body ground | Multiplex communication signal circuit | Engine switch on (IG) | Signal waveform |
CHECK OVERHEAD J/B |

Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition |
+B1 (R5-1) - Body ground | L - Body ground | Power source circuit | Always | 10 to 14 V |
RRMP (R5-3) - Body ground | O - Body ground | Rear personal light power source circuit | Always | 10 to 14 V |
ILLB (R5-4) - Body ground | L - Body ground | Rear interior light power source circuit | Always | 10 to 14 V |
CTY (R5-12) - Body ground | W - Body ground | Seat illumination light circuit | Seat illumination light goes off | 10 to 14 V |
CTY (R5-12) - Body ground | W - Body ground | Seat illumination light circuit | Seat illumination light comes on | Below 1 V |
ILL (R5-13) - Body ground | BR - Body ground | Interior light circuit | Interior light goes off | 10 to 14 V |
ILL (R5-13) - Body ground | BR - Body ground | Interior light circuit | Interior light comes on | Below 1 V |
SHFT (R5-14) - Body ground | Y - Body ground | Shift illumination circuit | Shift illumination goes off | 10 to 14 V |
SHFT (R5-14) - Body ground | Y - Body ground | Shift illumination circuit | Shift illumination comes on | Below 1 V |
GND3 (R5-18) - Body ground | W-B - Body ground | Ground | Always | Below 1 V |
RGND (R5-19) - GND3 (R5-18) | W-B - W-B | Interior light ground | Always | Below 1 V |
LILL (R5-32) - CTY (R5-12) | B - W | Seat illumination circuit | Always | Below 1 Ω |
RILL (R5-33) - ILL (R5-13) | P - BR | Interior light circuit | Always | Below 1 Ω |
CILL (R5-34) - GND3 (R5-18) | P - W-B | Interior light switch (ON/OFF) circuit | Interior light switch off | 10 to 14 V |
CILL (R5-34) - GND3 (R5-18) | P - W-B | Interior light switch (ON/OFF) circuit | Interior light switch on | Below 1 V |
DOOR (R5-35) - GND3 (R5-18) | G - W-B | Interior light switch (DOOR) circuit | Interior light switch off | 10 to 14 V |
DOOR (R5-35) - GND3 (R5-18) | G - W-B | Interior light switch (DOOR) circuit | Interior light switch on | Below 1 V |
CHECK AFS ECU |
*2: LHD
*3: With AFS

Symbols (Terminal No.) | Wiring Color | Terminal Description | Condition | Specified Condition |
SBF (A28-1) - SGF (A28-17) | R-B - G-R | Vehicle height signal (To height control sensor) | Engine switch off | Below 1 V |
Engine switch on (IG) | 4.5 V to 5.5 V | |||
SPDL (A28-6) - E1 (A27-1) | P-B - W-B *1 R-L - W-B *2 | Vehicle speed signal (To skid control ECU) | Vehicle is driving at approx. 30 km/h (19 mph) | Pulse generation (see waveform 1) |
SPDR (A28-7) - E1 (A27-1) | G-W - W-B | Vehicle speed signal (To skid control ECU) | Vehicle is driving at approx. 30 km/h (19 mph) | Pulse generation (see waveform 1) |
BR1+ (A28-9) - BR1- (A28-10) | LG-R - O | Headlight swivel motor RH | Engine switch off | Below 1 V |
Engine running, light control switch in HEAD, driving at more than 10 km/h (6 mph) and turning the steering wheel to right more than 7.5° | Pulse generation (see waveform 2) | |||
BR2+ (A28-11) - BR2- (A28-12) | L-B - L-Y | Headlight swivel motor RH | Engine switch off | Below 1 V |
Engine running, light control switch in HEAD, driving at more than 10 km/h (6 mph) and turning the steering wheel more than 7.5° | Pulse generation (see waveform 2) | |||
LR1+ (A28-13) - LR1- (A28-14) | L - BR-W | Headlight leveling actuator RH | Engine switch off | Below 1 V |
Engine running, light control switch in HEAD, the vehicle is standing still or bouncing | Pulse generation (see waveform 3) | |||
LR2+ (A28-15) - LR2- (A28-16) | P - LG | Headlight leveling actuator RH | Engine switch off | Below 1 V |
Engine running, light control switch in HEAD, the vehicle is standing still or bouncing | Pulse generation (see waveform 3) | |||
SGF (A28-17) - E1 (A27-1) | G - R | Vehicle height signal (To height control sensor) | Always | Below 1 V |
SMGR (A28-18) - E1 (A27-1) | W-R - W-B | Headlight swivel motor RH | Always | Below 1 V |
SMGL (A28-19) - E1 (A27-1) | P-G - W-B | Headlight swivel motor LH | Always | Below 1 V |
SMBR (A28-21) - SMGR (A28-18) | GR - W-R | Headlight swivel motor RH | Engine switch off | Below 1 V |
Engine switch on (IG) | 4.5 V to 5.5 V | |||
SMBL (A28-22) - SMGL (A28-19) | W - P-G | Headlight swivel motor LH | Engine switch off | Below 1 V |
Engine switch on (IG) | 4.5 V to 5.5 V | |||
SMR (A28-23) - SMGR (A28-18) | G-B - W-R | Headlight swivel motor RH | Engine switch off | Below 1 V |
Engine switch on (IG) | 0.3 V to 4.6 V | |||
SML (A28-24) - SMGL (A28-19) | Y-B - P-G | Headlight swivel motor LH | Engine switch off | Below 1 V |
Engine switch on (IG) | 0.3 V to 4.6V | |||
BL1+ (A28-25) - BL1-(A28-26) | B-L - L-W | Headlight swivel motor LH | Engine switch off | Below 1 V |
Engine running, light control switch in HEAD, driving at more than 10 km/h (6 mph) and turning the steering wheel to left more than 7.5° | Pulse generation (see waveform 2) | |||
BL2+ (A28-27) - BL2-(A28-28) | L-R - B-Y | Headlight swivel motor LH | Engine switch off | Below 1 V |
Engine running, light control switch in HEAD, driving at more than 10 km/h (6 mph) and turning the steering wheel to left more than 7.5° | Pulse generation (see waveform 2) | |||
LL1+ (A28-29) - LL1-(A28-30) | R-G - G | Headlight leveling actuator LH | Engine switch off | Below 1 V |
Engine running, light control switch in HEAD, the vehicle is standing still or bouncing | Pulse generation (see waveform 3) | |||
LL2+ (A28-31) - LL2-(A28-32) | Y-R - V-R | Headlight leveling actuator LH | Engine switch off | Below 1 V |
Engine running, light control switch in HEAD, the vehicle is standing still or bouncing | Pulse generation (see waveform 3) | |||
E1 (A27-1) - Body ground | W-B - Body ground | Ground | Always | Below 1 V |
IG (A27-2) - E1 (A27-1) | B-O - W-B | Power source circuit (To engine switch) | Engine switch off | Below 1 V |
Engine switch on (IG) | 10 to 14 V | |||
MPX1 (A27-5) - E1 (A27-1) | BR - W-B *3 | Multiplex communication signal | Engine switch on (IG) | Signal waveform |
MPX2 (A27-6) - E1 (A27-1) | BR-B - W-B *3 | Multiplex communication signal | Engine switch on (IG) | Signal waveform |
SS+ (A27-7) -SS- (A27-8) | L - LG | Steering sensor signal (To position sensor) | Engine idling, slowly turn steering wheel | Pulse generation |
SHRL (A27-9) - SGR (A27-20) | B-W - R-Y | Vehicle height signal (To height control sensor rear) | Engine switch off | Below 1 V |
Engine switch on (IG) , bouncing the vehicle | 0.5 to 4.5 V | |||
SHFL (A28-2) - SGF (A28-17) | G-Y - G-R | Vehicle height signal (To height control sensor front) | Engine switch off | Below 1 V |
Engine switch on (IG) , bouncing the vehicle | 0.5 to 4.5 V | |||
SBR (A27-10) - SGR (A27-20) | W - R-Y | Vehicle height signal (To height control sensor rear) | Engine switch off | Below 1 V |
Engine switch on (IG) | 4.5 to 5.5 V | |||
SBF (A28-1) - SGF (A28-17) | R-B - G-R | Vehicle height signal (To height control sensor front) | Engine switch off | Below 1 V |
Engine switch on (IG) | 4.5 to 5.5 V |
Waveform 1
Item Contents Terminal SPDL - GND
SPDR - GNDTool setting 5 V/DIV., 2 ms./DIV. Vehicle condition Vehicle is driving at approximately 30 km/h (19 mph) Waveform 2
Item Contents Terminal BL1+ - BL1-
BL2+ - BL2-
BR1+ - BR1-
BR2+ - BR2-Tool setting 10 V/DIV., 5 ms./DIV. Vehicle condition - Engine running, light control switch in HEAD, driving at more than 10 km/h (6 mph) and turning the steering wheel more than 7.5°
- If the value is not within the standard range, it is possible there is some defect on the vehicle side. Inspect the fuse, wire harness and connector.
- Engine running, light control switch in HEAD, driving at more than 10 km/h (6 mph) and turning the steering wheel more than 7.5°
Waveform 3
Item Contents Terminal LR1+ - LR1-
LR2+ - LR2-
LL1+ - LL1-
LL2+ - LL2-Tool setting 10 V/DIV., 5 ms./DIV. Vehicle condition - Engine running, light control switch in HEAD, driving at more than 10 km/h (6 mph) and turning the steering wheel more than 7.5°
- If the value is not within the standard range, it is possible there is some defect on the vehicle side. Inspect the fuse, wire harness and connector.
- Engine running, light control switch in HEAD, driving at more than 10 km/h (6 mph) and turning the steering wheel more than 7.5°
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