Page 85 of 557
6-34 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
1. ECM (PCM)
2. ECM (PCM) couplers
(Viewed from harness side)
1. ECM (PCM)
2. Couplers
3. Body ground
4. Service wire
16
C03 C02 C01
1
2
1 2 3
4 5 6
7 8 9 10 11 1 2
3 4 5 6 7 8 1 2
3 4 5 6 7 8 9 10 11 12 13
12
13 14 15
16 17 18 19
20 21 22 9 10
11 12 13 14 15 14 15
16 17 18 19 20 21 22 23 24
25 26
INSPECTION OF ECM (PCM) AND ITS
CIRCUITS
ECM (PCM) and its circuits can be checked at ECM (PCM) wiring
couplers by measuring voltage and resistance.
CAUTION:
ECM (PCM) cannot be checked by itself. It is strictly prohib-
ited to connect voltmeter or ohmmeter to ECM (PCM) with
coupler disconnected from it.
Voltage Check
1) Remove ECM (PCM) (1) from body referring to Section 6E.
2) Check voltage at each terminal of couplers (2) connected.
NOTE:
As each terminal voltage is affected by the battery voltage,
confirm that it is 11 V or more when ignition switch is ON.
Page 86 of 557

ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-35
CONNECTOR “C02”
TER-
MINALWIRE
COLORCIRCUITSTANDARD
VOLTAGECONDITION
1BECM (PCM) ground––
2W/BlPower source10 – 14 VIgnition switch ON
3—Blank——
4—Blank——
5—Blank——
6—Blank——
7R/GEVAP canister purge valve10 – 14 VIgnition switch ON
8G/OrShift solenoid B (A / T)
0 VIgnition switch ON, selector lever at “P”
range
8G/OrShift solenoid-B (A / T)
10 – 14 VIgnition switch ON, selector lever at “D”
range
9G/WShift solenoid A (A / T)
0 VIgnition switch ON, selector lever at “P”
range
9G/WShift solenoid-A (A / T)
10 – 14 VIgnition switch ON, selector lever at “D”
range
10OrIgniter (IGT)——
11Gr / YISC actuator——
12Y/BFuel injector10 – 14 VIgnition switch ON
13B/BlGround for injector——
14WPower source for back-up10 – 14 VIgnition switch ON and OFF
15W/BlPower source10 – 14 VIgnition switch ON
16Gr / BISC actuator relay0.3 – 1.0 VIgnition switch ON
17V/YMalfunction indicator lamp0.2 – 2.0 VIgnition switch ON17V/YMalfunction indicator lamp10 – 14 VWhen engine running
18V/GImmobilizer indicator lamp0.2 – 2.0 VIgnition switch ON18V/GImmobilizer indicator lamp10 – 14 VWhen engine running at idle
19Lg / BHeater of H02S-210 – 14 VIgnition switch ON
20BlRadiator fan control relay
10 – 14 VIgnition switch ON, Engine coolant
temp: Below 91.5C (197F)
20BlRadiator fan control relay
0.3 – 1.0 VIgnition switch ON, Engine coolant
temp: 96.0C (205F) or higher
21P/WFuelpumprelay0.3 – 1.3 VFor 2 seconds after ignition switch ON21P/WFuel pump relay10 – 14 VAfter the above time
22Bl / BMain relay0.4 – 1.5 VIgnition switch ON
23–Blank——
24Gr / RISC actuator——
25Y/REFE heater relay10 – 14 VIgnition switch ON
26B/RGround for injector——
Page 89 of 557

6-38 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
1 2
1. ECM (PCM)
coupler disconnected
2. Ohmmeter
RESISTANCE CHECK
1) Disconnect ECM (PCM) couplers from ECM (PCM) with ignition
switch OFF.
CAUTION:
Never touch terminals of ECM (PCM) itself or connect
voltmeter or ohmmeter.
2) Check resistance between each terminal of couplers discon-
nected.
CAUTION:
Be sure to connect ohmmeter probe from wire harness
side of coupler.
Be sure to turn OFF ignition switch for this check.
Resistance in table below represents that when parts
temperature is 20C (68F).
TERMINALSCIRCUITSTANDARD RESISTANCE
C01-8 to C03-20H02S-1 heater11.7 – 14.3 Ω
C02-19 to C03-20H02S-2 heater11.7 – 14.3 Ω
C02-12 to C02-2 / 15Fuel injector2.4 – 3.6 Ω
C02-7 to C02-2 / 15EVAP canister purge valve30 – 34 Ω
C02-21 to C03-20Fuel pump relay100 – 120 Ω
C02-16 to C02-2 / 15ISC actuator relay100 – 120 Ω
C02-25 to C02-2 / 15EFE heater relay100 – 120 Ω
C02-8 to Body groundShift solenoid-B8 – 20 Ω
C02-9 to Body groundShift solenoid-A8 – 20 Ω
C02-20 to C02-2 / 15Radiator fan control relay100 – 120 Ω
C02-22 to C02-14Main relay100 – 120 Ω
C02-1 to Body groundGroundContinuity
C02-13 to Body groundGroundContinuity
C02-26 to Body groundGroundContinuity
Page 90 of 557
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-39
INFORMATION SENSORS
-1. MAP sensor
-2. TP sensor
-3. IAT sensor
-4. ECT sensor
-5. Heated oxygen sensor-1
-6. VSS
-7. Ignition coil
-8. Battery
-9. CMP sensor (in Distributor)
-10. A/C contoller (if equipped)
-11. CKP sensor
-12. CTP switch (in ISC actuator)
-13. Heated oxygen sensor-2OTHERS
A: ECM (PCM)
B: Main relay
C: EVAP canister
D: Injector resistor
E: EFE heater
F: Electric load diode CONTROL DEVICES
a: Fuel injector
b: EVAP canister purge valve
c: Fuel pump relay
d: Malfunction indicator lamp
e: ISC actuator
f: Radiator fan control relay
g: Igniter
h: EFE heater relay
i: ISC actuator relay
COMPONENT LOCATION
Page 91 of 557

6-40 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
“IG COIL METER”Main relay
Ignition switch
In fuseMalfunction indicator lamp in combination meter
TABLE A-1 MALFUNCTION INDICATOR LAMP CIRCUIT CHECK – LAMP DOES
NOT COME “ON” AT IGNITION SWITCH ON (BUT ENGINE AT STOP)
CIRCUIT DESCRIPTION
When the ignition switch is turned ON, ECM (PCM) causes the main relay to turn ON (close the contact point).
Then, ECM (PCM) being supplied with the main power, turns ON the malfunction indicator lamp (MIL). When the
engine starts to run and no malfunction is detected in the system, MIL goes OFF but if a malfunction was or is de-
tected, MIL remains ON even when the engine is running.
INSPECTION
STEPACTIONYESNO
1MIL Power Supply Check
1) Turn ignition switch ON.
Do other indicator / warning lights in
combination meter comes ON?Go to Step 2.“IG COIL METER” fuse blown,
main fuse blown, ignition
switch malfunction, “B/W”
circuit between “IG COIL
METER” fuse and
combination meter or poor
coupler connection at
combination meter.
2ECM (PCM) Power and Ground Circuit
Check
Does engine start?Go to Step 3.Go to TABLE A-3 ECM (PCM)
POWER AND GROUND
CIRCUIT CHECK.
If engine is not cranked, go to
DIAGNOSIS in SECTION 8A.
3MIL Circuit Check
1) Turn ignition switch OFF and disconnect
connectors from ECM (PCM).
2) Check for proper connection to ECM
(PCM) at terminal C02-17.
3) If OK, then using service wire, ground
terminal C02-17 in connector
disconnected.
Does MIL turn on at ignition switch ON?Substitute a known-
good ECM (PCM) and
recheck.Bulb burned out or “V/Y” wire
circuit open.
Page 92 of 557
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-41
TABLE A-2 MALFUNCTION INDICATOR LAMP CIRCUIT CHECK – LAMP
REMAINS “ON” AFTER ENGINE STARTS
WIRING DIAGRAM / CIRCUIT DESCRIPTION – Refer to table A-1.
INSPECTION
STEPACTIONYESNO
1Diagnostic Trouble Code (DTC) check
1) Check DTC referring to DTC CHECK section.
Is there any DTC(s)?Go to Step 2 of ENGINE
DIAG. FLOW TABLE.Go to Step 2.
2DTC check
Start engine and recheck DTC while engine
running.
Is there any DTC(s)?Go to Step 3.
3MIL Circuit check
1) Turn OFF ignition switch.
2) Disconnect connectors from ECM (PCM).
Does MIL turn ON at ignition switch ON?“V/Y” wire circuit
shorted to ground.Substitute a known-good
ECM (PCM) and
recheck.
Page 93 of 557

Main fuse Ignition switch
Main fuseMalfunction indicator lamp in combination meter
Relay box“IG COIL METER”
6-42 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
TABLE A-3 ECM (PCM) POWER AND GROUND CIRCUIT CHECK – MIL
DOESN’T LIGHT AT IGNITION SWITCH ON AND ENGINE DOESN’T
START THOUGH IT IS CRANKED UP
CIRCUIT DESCRIPTION
When the ignition switch tuned ON, the main relay turns ON (the contact point closes) and the main power is sup-
plied to ECM (PCM).
INSPECTION
STEPACTIONYESNO
1Main Relay Operating Sound Check
Is operating sound of main relay heard at ignition switch ON?Go to Step 5.Go to Step 2.
2Main Relay Check
1) Turn OFF ignition switch and remove main relay (1).
2) Check for proper connection to main relay (1) at terminal
3 and 4.
3) Check resistance between each two terminals. See Fig. 1
and 2.
Between terminals 1 and 2: Infinity
Between terminals 3 and 4: 100 – 120 Ω
4) Check that there is continuity between terminals 1 and 2
when battery is connected to terminals 3 and 4. See Fig. 3.
Is main relay in good condition?Go to Step 3.Replace main
relay.
3Fuse Check
Is main “FI” fuse in good condition?Go to Step 4.Check for short in
circuits connected
to this fuse.
4ECM (PCM) Power Circuit Check
1) Turn OFF ignition switch, disconnect connectors from ECM
(PCM) and install main relay.
2) Check for proper connection to ECM (PCM) at terminals
C03-20, C02-2, C02-15 and C02-22.
3) If OK, then measure voltage between terminal C03-20 and
ground, C02-22 and ground with ignition switch ON.
Is each voltage 10 – 14 V?Go to Step 5.“B/W”, “W/R” or
“Bl / B” circuit
open.
Page 94 of 557
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-43
Fig. 1 for Step 2 Fig. 2 for Step 2 Fig. 3 for Step 2
1. Main relay
2. Relay box
STEPACTIONYESNO
5ECM (PCM) Power Circuit Check
1) Using service wire, ground terminal C02-22 and
measure voltage between terminal C02-2 and
ground at ignition switch ON.
Is it 10 – 14 V?Check ground circuits
“Bl / B” and “W / Bl” for
open.
If OK, then substitute a
known-good ECM
(PCM) and recheck.Go to Step 6.
6Is operating sound of main relay heard in Step 1?Go to Step 7.“W / R” or “W / Bl” wire
open.
7Main Relay Check
1) Check main relay according to procedure in
Step 2.
Is main relay in good condition?“W / R” or “W / Bl” wire
open.Replace main relay.