Page 2265 of 4592

A03606
ECM
STA 11
E1 E4 Instrument
Panel J/BPark/Neutral
Position Switch
B
J6 J7
B CJ/C IG210 11
IG26 5
GR B±W
B±WGR B±W
J/C J29
B B 3
1J 4
1K
5
1B 1K5
STARTER
R
8
7
W±R
IG SwitchW±R
Engine Room
J/B No.2B
B FL
Block
B±G
B±R
BatteryStarter 11
W±B
A
J9
J/C
IF
42L
1
2A
3
2B
AM2
MAINST
Relay11 2 J
92K 52D 1 1
F11 F91 5
2 3
S2B±R MAIN
FL
GR
S1
GR
J6
± DIAGNOSTICSENGINE
DI±113
Starter Signal Circuit
CIRCUIT DESCRIPTION
When the engine is cranked, the intake air flow is slow, so fuel vaporization is poor. A rich mixture is therefore
necessary in order to achieve good startability. While the engine is being cranked, the battery positive volt-
age is applied to terminal STA of the ECM. The starter signal is mainly used to increase the fuel injection
volume for the starting injection control and after±start injection control.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
This diagnostic chart is based on the premise that the engine is cranked normally. If the engine is not
cranked, proceed to the problem symptoms table on page DI±21.
DI01K±12
Page 2266 of 4592

BE6653A03027A09272
START
STA
(±) (+)
DI±114
± DIAGNOSTICSENGINE
TOYOTA hand±held tester:
1 Connect TOYOTA hand±held tester, and check STA signal.
PREPARATION:
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and push the TOYOTA hand±held tester main switch ON.
CHECK:
Read the STA signal on the TOYOTA hand±held tester while the starter operates.
OK:
Ignition Switch PositionONSTART
STA signalOFFON
OK Proceed to next circuit inspection shown on
problem symptoms table (See page DI±21).
NG
2 Check for open in harness and connector between ECM and starter relay (Mark-
ing: ST) (See page IN±29).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±29).
OBD II scan tool (excluding TOYOTA hand±held tester):
1 Check voltage between terminal STA of ECM connector and body ground.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal STA of the ECM connec-
tor and body ground, during the engine cranking.
OK:
Voltage: 6 V or more
OK Proceed to next circuit inspection shown on
problem symptoms table (See page DI±3).
Page 2267 of 4592
± DIAGNOSTICSENGINE
DI±115
NG
2 Check for open in harness and connector between ECM and starter relay (Mark-
ing: ST) (See page IN±29).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±29).
Page 2268 of 4592
A09403
ECM
+B 12
E4 B±Y J/C
B
J24 J23B
B±Y
Instrument
Panel J/B 22J 2K7
W±R EFI
Relay 1 3
52
2F4
W±B
2A 1
AM2
42L
B
FL
Block
MAIN
FL
B±GEngine
J/B No.2
5
1B
531K71W
IGN
1K
Room
W±R
IG
Switch
7 6
E6
BR
B±R
EC
E1
F11
F9EB
1
1
EFI
J20
J/C A
A
Battery
BR
16 B±R DI±116
± DIAGNOSTICSENGINE
ECM Power Source Circuit
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, battery positive voltage is applied to the coil, closing the contacts of
the EFI main relay (Marking: EFI) and supplying power to terminal +B of the ECM.
WIRING DIAGRAM
DI01L±07
Page 2269 of 4592
A09291BE6653
A09273
ON
+B
E1
(±) (+)
± DIAGNOSTICSENGINE
DI±117
INSPECTION PROCEDURE
1 Check voltage between terminals +B and E1 of ECM connector.
PREPARATION:
(a) Remove the glove compartment (See Pub. No. RM654U,
page SF±64).
(b) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals +B and E1 of the ECM
connector.
OK:
Voltage: 9 ± 14 V
OK Proceed to next circuit inspection shown on
Problem symptoms table (See page DI±21).
NG
2 Check for open in harness and connector between terminal E1 of ECM and body
ground (See page IN±29).
NG Repair or replace harness or connector.
OK
3 Check EFI main relay (Marking: EFI) (See Pub. No. RM654U, page SF±40).
NG Replace EFI main relay.
OK
4 Check EFI fuse (See page DI±110, step 2).
NG Check for short in all harness and components
connected to EFI fuse.
OK
Page 2270 of 4592
A00355
IGN Fuse
Instrument Panel J/B
DI±118
± DIAGNOSTICSENGINE
5 Check for open in harness and connector between EFI main relay (Marking: EFI)
and battery, and EFI main relay and ECM (See page IN±29).
NG Repair or replace harness or connector.
OK
6 Check IGN fuse.
PREPARATION:
Remove the IGN fuse from the instrument panel J/B.
CHECK:
Check the continuity of the IGN fuse.
OK:
Continuity
NG Check for short in all harness and components
connected to IGN fuse.
OK
7 Check ignition switch (See Pub. No. RM654U, page BE±14).
NG Replace ignition switch.
OK
Check for open in harness and connector between ignition switch and EFI main relay, and EFI
main relay and body ground (See page IN±29).
Page 2271 of 4592
A09404
9
W±L
IJ2
E6 10
IG3
E6 18
LOCK IN
E1 16
EC
BRJ20
IJ210
BR 1
2A/C Compressor
Lock SensorECM
BR W±L
W±L
B
B BRJ/C
AA
A
BR
IG3 J7
6J/C
BR
± DIAGNOSTICSENGINE
DI±119
A/C Compressor Lock Sencor Circuit
CIRCUIT DESCRIPTION
This sensor sends 1 pulse par engine revolution to the ECM. If the number ratio of the compressor speed
divided by the engine speed is smaller than a predetermined value, the ECM turns the compressor off. And,
the indicator flashes at about 1 second intervals.
WIRING DIAGRAM
INSPECTION PROCEDURE
1 Check A/C compressor.
PREPARATION:
(a) Check the compressor drive belt tension (See Pub. No. RM654U, page AC±16).
(b) Check if the compressor does not lock during operation with the engine started, and the blower switch
and A/C switch ON.
NG Adjust drive belt tension or repair compressor
(See Pub. No. RM654U, page AC±17).
OK
DI01N±05
Page 2272 of 4592
N15622
12
N02774
LOCK IN Signal Waveform
20 msec./Division (Idling) 0 V
0.2 V/Div.
DI±120
± DIAGNOSTICSENGINE
2 Check A/C compressor lock sensor.
PREPARATION:
Disconnect the compressor lock sensor connector.
CHECK:
Measure the resistance between terminals 1 and 2 of the com-
pressor lock sensor connector.
OK:
Resistance: 65 ± 125 W at 20°C (68°F)
Reference: INSPECTION USING OSCILLOSCOPE
During cranking or idling, check the waveform between termi-
nals LOCK IN and E1 of the ECM connector.
HINT:
The correct waveform appears as shown.
NG Replace compressor lock sensor
(See Pub. No. RM654U, page AC±40).
OK
3 Check harness and connector between A/C compressor lock sensor and ECM
(See page IN±29).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±29).