1991 LEXUS SC400 engine

Engine & ECT ECU
TERMINALS OF ENGINE & ECT ECU
TerminalNo.SymbolConnectionTerminalNo.SymbolConnection
E9 ± 1IGSWIgnition SwitchE9 ± 31+ BEFI Main Relay
2SPDNo. 1 Speed Sensor32+ B1EFI Main Relay
3KDKick±Down Switch33BATTBattery
4STPStop light Switch34A/CA/C Control Assembly
5±35±
6WªCHECKº Engine Warning Light36±
7RNeutral Start Switch37TRTRAC ECU
8±38NEOTRAC ECU
92Neutral Start Switch39VTO2TRAC ECU
10LNeutral Start Switch40VTO1TRAC ECU
11ADCC ECUE10 ± 1NCO T/M Input Speed Sensor
12OD1CC ECU2±
13±3SP2No. 2 Speed Sensor for ECT
14±4E11ECU Ground
15±5G2Cam position Sensor
16±6G1Cam position Sensor
17TTTDCL7NFEngine Speed Sensor
18PECT Pattern Select Switch8±
19TE2Check Connector9S2ECT Solenoid Value
20TE1Check Connector10S1ECT Solenoid Value
21D1Fuel Pump ECU11±
22FPCFuel Pump ECU12±
23ACMGA/C Magnet Clutch Relay13SLN
No.3 ECT Solenoid Valve
24M±RELEFI Main Relay14SLUNo.4 ECT Solenoid Valve
25±15±
26±16±
27±17#10No.3 and No.5 Injectors
28OD2O/D Main Relay18#20No.4 and No.6 Injectors
29±19#20No.2 and No.8 Injectors
30±20#40No.1 and No.7 Injectors
Engine & ECT ECU Terminals
FI±126 ± Electronic Control \
System (Engine & ECT ECU)EFI SYSTEM
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TERMINALS OF ENGINE & ECT ECU (Cont'd)
TerminalNo.SymbolConnectionTerminalNo.SymbolConnection
E10± 21NCOT/M Input Speed SensorE10 ± 51±
22±52HTL2LH Sub±Oxygen Sensor Heater
23SP2No.2 Speed Sensor for ECT53HTR2RH Sub±Oxygen Sensor Heater
24±54±
25G2LH (No.2) Cam Position Sensor55±
26G1RH (No.1) Cam Position Sensor56IGT2No.2 Igniter for RH Bank
27NEEngine Speed Sensor57IGT1No.1 Igniter for LH Bank
28VF2Check Connector58IGF1No.1 Igniter for LH Bank
29VF1Check Connector59IGF2No.2 Igniter for RH Bank
30±60±
31±61±
32ISC4ISC Valve62±
33ISC3ISC Valve63IDL2Sub±Throttle Position Sensor
34ISC2ISC Valve64IDL1Throttle Position Sensor
35ISC1ISC Valve65E2Sensor Ground
36* EGR4EGR Valve66KSAir Flow Meter
37* EGR3EGR Valve67OXR2
38* EGR2EGR Valve68OXL2LH Sub±Oxygen Sensor
39* EGR1EGR Valve69E1ECU Ground39* EGRVSV for EGR69E1ECU Ground
40±70±
41VCThrottle Position Sensor
Air Flow Meter71HTL1LH Main Oxygen Sensor
42VTA2Fuel Pump ECU72HTR1RH Main Oxygen Sensor
43VTA1A/C Magnet Clutch Relay73FPUVSV for Fuel Pressure Control
Value
44THWWater Temp. Sensor74* PA GVSV for EVAP
45THAIntake Air Temp. Sensor75±
46THGEGR Gas Temp. Sensor76NSWNeutral Start Switch
47OXR1RH Main Oxygen Sensor77STAStarter Relay
48OXL1LH Main Oxygen Sensor78STJCold Start Injector
49KNK2RH (No.2) Knock Sensor79E02Power Ground
50KNK1LH (No.1) Knock Sensor80E01Power Ground
Engine & ECT ECU Terminals
*USA spec. only
*  A/T only
FI±127EFI SYSTEM ± Electronic Control System (Engine & ECT ECU)
WhereEverybodyKnowsYourName

COMPONENTS FOR REMOVAL AND
INSTALLATION
INSPECTION OF ENGINE & ECT ECU
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
2. DISCONNECT ENGINE & ECT ECU FROM FLOOR P ANEL
(a) Remove the two clips, and pull out the instrument panel
under cover.
FI±128
EFI SYSTEM
± Electronic Control System (Engine & ECT ECU)
WhereEverybodyKnowsYourName

(b) Take out the front side of the floor carpet.
(c) Remove the two nuts and protector.
(d) Remove the nut, and disconnect the engine & ECT ECU
from the floor panel.
3. INSPECT ENGINE & ECT ECU
A. Install SST (check harness) between engine & ECT ECU and wiring connectors
HINT:
wECU connectors are water±proof and are the bolt type.
w For water±proof type connectors, in order to measure
the voltage of ECU terminals and the resistance of
connected parts, connect a check harness (SST
09990±01000) between the ECU and wiring
connectors, then perform the inspection.
w Avoid inserting a tester probe from the other side of
connector as this noticeably reduces the water±proof
ability.
w Disconnect the ECU connectors by fully loosening the
bolt.
(a) Remove the bolt, and disconnect the two ECU
connectors.
NOTICE:
w Do not pull the wiring harness when disconnecting the
connectors.
w When disconnecting the connector, the ECU's back±up
power source is cut off, so the malfunction codes, etc.
recorded in the ECU memory are cancelled.
w Never insert a tester probe or male terminal used for
inspection purposes into the female terminal of the
vehicle wire harness. Otherwise, the female terminal may
be widened, which can reselt in faulty connection.
(b) Connect SST (check harness) between ECU and wiring
connectors.
SST 09990±01000
HINT: SST (check harness) connector terminals are ar-
ranged the same as those of the ECU. FI±129
EFI SYSTEM
± Electronic Control System (Engine & ECT ECU)
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B. Inspect voltage of engine & ECT ECUCheck the voltage between each terminal.w Turn the ignition switch ON.
w Measure the voltage at each terminal.
HINT:
w Perform all voltage measurements with the connectors
connected.
w Verify that the battery voltage is 11 V or more when the
ignition switch is ON.
FI±130EFI SYSTEM ± Electronic Control System (Engine & ECT ECU)
WhereEverybodyKnowsYourName

Voltage at Engine (& ECT) ECU Wiring Connectors
TerminalsConditionSTD voltage (V)
BATT (E9 ± 33) ± E1 (E10 ± 69)±10 ± 14
IGSW (E9 ± 1)
+B (E9 ± 31) ± E1 (E10 ± 69)IG SW ON10 ± 14
+B1 (E9 ± 32)
VC (E10 ± 41) ±E2 (E10 ± 65)±4.0 ± 6.0
IDL1 (E10 ± 64)E2 (E10 65)Throttle (or sub±throttle) valve fully closed1.0 or less
IDL2 (E10 ± 63)± E2 (E10 ± 65)IG SW ONThrottle (or sub±throttle) valve fully open10 ± 14
VTA1 (E10 ± 43)E2 (E10 65)Throttle (or sub±throttle) valve fully closed0.1 ± 1.0
VTA1 (E10 ± 42)± E2 (E10 ± 65)Throttle (or sub±throttle) valve fully open3.0 ± 6.0
KS (E10 ± 66)±E1 (E10 ± 69)IdlingPulse generation
THA (E10 ± 45)±E2 (E10 ± 65)IdlingIntake air temp. 20°C (68 °F)1.0 ± 3.0
THW (E10 ± 44)±E2 (E10 ± 65)IdlingEngine Coolant temp. 80 °C (176 °F)0.1 ± 1.0
STA (E10 ± 77)±E1 (E10 ± 69)Cranking6.0 or more
#10 (E10 ± 20)
#20 (E10 ± 19)E01 (E10 ± 80)
IG SW ON10 ± 14
#30 (E10 ± 18)±
E02 (E10 ± 79)
#40 (E10 ± 17)IdlingPulse generation
IGT1 (E10 ± 57)E1 (E10 69)IdlingPulse generationIGT2 (E10 ± 56)± E1 (E10 ± 69)IdlingPulse generation
IGF1 (E10 ± 58)E1 (E10 69)IdlingPulse generationIGF2 (E10 ± 59)± E1 (E10 ± 69)IdlingPulse generation
G1 (E10 ± 26)G1 ± (E10±6)IdlingPulse generationG2 (E10 ± 25)±
G2 ± (E10±5) IdlingPulse generation
NE (E10 ± 27)±G ± (E10 ± 7)IdlingPulse generation
M ± REL (E9 ± 24)±E1 (E10 ± 69)IG SW ON10 ± 14
FPC (E9 22)E1 (E10 69)Cranking, Sudden racing (6,000 rpm)4.2 ± 6.0FPC (E9 ± 22)± E1 (E10 ± 69)IdlingPulse generation
D1 (E9 ± 21)±E1 (E10 ± 69)Idling7.5 or more
FPU (E10 73)E1 (E10 69)IG SW ON10 ± 14FPU (E10 ± 73)± E1 (E10 ± 69)Restarting high temp.2.0 or less
PAG (E10 ± 74)±E01 (E10 ± 69)IG SW ON10 ± 14
Engine & ECT ECU Terminals
FI±131EFI SYSTEM
± Electronic Control System (Engine & ECT ECU)
WhereEverybodyKnowsYourName

Voltage at Engine (& ECT) ECU Wiring Connectors (Cont'd)
TerminalsConditionSTD voltage (V)
ISC1 (E10 ± 35)
ISC2 (E10 ± 34)E1 (E10 69)IG SW ON10 14ISC3 (E10 ± 33)± E1 (E10 ± 69)IG SW ON10 ± 14
ISC4 (E10 ± 32)
VF1 (E10 ± 29)E1 (E10 69)Maintain engine speed at 2,500 rpm for 120 seconds10 40VF2 (E10 ± 28)± E1 (E10 ± 69)Maintain engine s eed at 2,500 rm for 120 seconds
after warming up then return to idling1.0 ± 4.0
OX1 (E10 ± 48)E1 (E10 69)Maintain engine speed at 2,500 rpm for 120 secondsPulse generation
OX2 (E10 ± 47)± E1 (E10 ± 69)Maintain engine s eed at 2,500 rm for 120 seconds
after warming up
Pulse generation
(0 ± 1.0)
HT (E10 ± 71)±E01 (E10 ± 80)Idle2.0 or less
KNK1 (E10 ± 50)E1 (E10 69)IdlePulse generationKNK2 (E10 ± 49)± E1 (E10 ± 69)IdlePulse generation
NSW (E10 76)E1 (E10 69)IG SW ONShift position ªPº or ªNº range1.0 or lessNSW (E10 ± 76)± E1 (E10 ± 69)IG SW ONEx. shift position ªPº or ªNº range10 ± 14
SP1 (E9 ± 2)±E1 (E10 ± 69)IG SW ONRotate driving wheel slowly.4 or more
TE1 (E9 ± 20)E1 (E10 69)IG SW ON10 14TE2 (E9 ± 19)± E1 (E10 ± 69)IG SW ON10 ± 14
W (E9 6)E1 (E10 69)IG SW ON2.0 or lessW (E9 ± 6)± E1 (E10 ± 69)Idle10 ± 14
OD1 (E9 ± 12)±E1 (E10 ± 69)IG SW ON4.0 ± 6.0
A/C (E9 34)E1 (E10 69)A/C SW ON (at idle)2.0 or lessA/C (E9 ± 34)± E1 (E10 ± 69)A/C SW OFF10 ± 14
ACMG (E9 23)E1 (E10 69)A/C SW ON (at idle)2.0 or lessACMG (E9 ± 23)± E1 (E10 ± 69)A/C SW OFF10 ± 14
TR (E9 ± 37)±E1 (E10 ± 69)IG SW ON10 ± 14
VT01 (E9 ± 40)E2 (E10 65)IG SW ONThrottle (or sub±throttle) valve fully closed1.0 or less
VT02 (E9 ± 39)± E2 (E10 ± 65)IG SW ONThrottle (or sub±throttle) valve fully open3.0 ± 5.5
NEO (E9 ± 38)±E1 ± (E10 ± 69)IG SW ON4.0 ± 6.0
Engine & ECT ECU Terminals
FI±132EFI SYSTEM ± Electronic Control System (Engine & ECT ECU)
WhereEverybodyKnowsYourName

B. Inspect resistance of engine & ECT ECU wiring connectorsNOTICE: Do not touch the ECU terminals.
Check the resistance between each terminal of the wiring
connectors.w Disconnect the SST (check harness) connectors
from the ECU.
w Measure the resistance at each terminal.
FI±133EFI SYSTEM ± Electronic Control System (Engine & ECT ECU)
WhereEverybodyKnowsYourName