Page 269 of 656
6-1-108 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0505 Idle Air Control System Malfunction
SYSTEM/WIRING DIAGRAM
DTC DETECTING CONDITION AND TROUBLE AREA
1. Throttle body 3. ECM (PCM) 5. FIA valve 7. Main relay
2. Idle air control valve 4. Sensed information 6. Main fuse
DTC DETECTING CONDITION TROUBLE AREA
•Engine idle speed is 100 r/min. or more lower than target idle
speed for longer than 20 sec. continuously.
or
•Engine idle speed is 200 r/min or more higher than target
idle speed for longer than 20 sec. continuously.
(2 driving cycle detection logic)•IAC valve or its circuit
•Abnormal air drawn in air intake system
•FIA (fast idle air) valve
Page 276 of 656

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-115
DTC P1510 Ecm Back-Up Power Supply Malfunction
WIRING DIAGRAM
CIRCUIT DESCRIPTION
Battery voltage is supplied to keep DTC memory, values that ECM has learned to control engine, etc. in ECM
even when ignition switch is turned OFF.
DTC DETECTING CONDITION AND TROUBLE AREA
DTC CONFIRMATION PROCEDURE
1) Connect scan tool to DLC with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data by using scan tool and run
engine at idle speed for 1min.
3) Check DTC by using scan tool.
TROUBLESHOOTING
1. Main fuse box 3. ECM (PCM)
2. To DLC
DTC DETECTING CONDITION TROUBLE AREA
Back-up circuit voltage lower than specification is detected
while engine is running.•ECM (PCM) back-up circuit
•ECM (PCM)
NOTE:
Check to make sure that following condition is satisfied when using this “DTC CONFIRMATION PRO-
CEDURE”.
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : – 8 – 110°C (18 – 230°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)
Step Action Yes No
1Was “ENGINE DIAG. FLOW TABLE” performed? Go to Step 2. Go to “ENGINE DIAG. FLOW
TABLE” in this section.
2 Battery voltage supply circuit check :
1) Remove ECM (PCM) cover.
2) While engine running, check voltage between E61-
2 and ground.
Is voltage 10 – 14 V?Poor E61-2 connection or
intermittent trouble.
Check for intermittent referring
to “INTERMITTENT AND
POOR CONNECTION” in
Section 0A.
If wire and connections are
OK, substitute a known-good
ECM (PCM) and recheck.“WHT” circuit open or short.
Page 277 of 656
6-1-116 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
Table B-1 Fuel Pump Circuit Inspection
WIRING DIAGRAM
INSPECTION
1. To ignition switch 4. Fuel pump relay
2. Main fuse 5. Fuel pump
3. Main relay 6. ECM (PCM)
CAUTION:
Check to make sure that connection is made between correct terminals.
Wrong connection can cause damage to ECM, wire harness etc.
Step Action Yes No
1 Fuel pump operation check :
1) Remove fuel filler cap.
2) Turn ON ignition switch.
Is fuel pump operation sound heard for 3 sec.
after ignition switch ON?Fuel pump circuit is in
good condition.Go to Step 2.
2 Fuel pump circuit check :
1) With ignition switch OFF, remove fuel pump
relay from connector.
2) Check for proper connection to relay at
each terminal.
3) If OK, using service wire, connect terminals
E07-7 and E07-8 of relay connector. (See
Fig.)
Is fuel pump heard to operate at ignition switch
ON?Go to Step 3.“BLU/BLK”, “PNK/BLK” or
“BLK” circuit open or fuel
pump malfunction.
Page 278 of 656
ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-117
Fig. for Step 2
Table B-2 Fuel Injectors and Circuit Inspection
WIRING DIAGRAM
3 Fuel pump relay check :
1) Check fuel pump relay referring to “FUEL
PUMP RELAY INSPECTION” in Section
6E2.
Is it in good condition?“BLK/WHT” or “WHT/
GRN” circuit open or poor
E61-23 connection.
If wire and connection are
OK, substitute a known-
good ECM (PCM) and
recheck.Replace fuel pump relay. Step Action Yes No
1. Fuel pump relay connector
1. To ignition switch 4. Injector No.1 7. Injector No.4 10. ECM (PCM)
2. Main fuse 5. Injector No.2 8. Injector No.5
3. Main relay 6. Injector No.3 9. Injector No.6
Page 282 of 656
ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-121
Table B-4 Idle Air Control System Inspection
WIRING DIAGRAM
INSPECTION
1. Throttle body 3. ECM (PCM) 5. Main fuse
2. Idle air control valve 4. Sensed information 6. Main relay
Step Action Yes No
1 Check engine idle speed and IAC duty
referring to “IDLE SPEED/IAC DUTY
INSPECTION” in Section 6E2.
Is idle speed/IAC duty within specifica-
tion?Go to Step 2. Go to Step 3.
2 Is engine idle speed kept specified speed
even with headlights turned ON?System is in good condition. Go to Step 3.
Page 285 of 656

6-1-124 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
Table B-6 A/C Condenser Fan Motor Relay Control System Inspection (If
Equipped)
WIRING DIAGRAM
INSPECTION
1. To ignition switch 3. A/C fuse 5. A/C condenser fan motor
2. Main fuse 4. A/C condenser fan motor relay 6. ECM (PCM)
WARNING:
Keep hands, tools, and clothing away from A/C condenser fan to help prevent personal injury. This
fan is electric and can come on whether or not the engine is running. The fan can start automatically
in response to the ECT sensor with the ignition switch in the “ON” position.
Step Action Yes No
1 1) Check DTC referring to “DTC CHECK” in this sec-
tion.
Is there any malfunction DTC?Go to applicable DTC
Diag. Flow Table.Go to Step 2.
2 1) Check A/C condenser fan for operation.
A/C condenser fan should be operated under follow-
ing condition A or B only.
A : When engine is running and A/C is operating.
B : When engine coolant temp. is 113°C (235°F) or
more with ignition switch ON.
Is check result as specified?This system is in
good condition.Go to Step 3.
3 1) Remove ECM (PCM) cover.
2) Check voltage between E61-22 terminal of ECM
(PCM) connected coupler and ground.
Other than conditions A and B in Step 2 :
10 – 14 V
Under condition A or B in Step 2 :
0 – 1 V
Is check result as specified?Fuse blown, “RED”,
“RED/BLK” or “RED/
BLU” circuit open,
malfunction of con-
denser fan motor or
relay.“YEL/GRN” circuit
open, “YEL/BLU” cir-
cuit open or short, or
relay malfunction.
If above are OK, sub-
stitute a known-good
ECM (PCM) and
recheck.
Page 431 of 656
7B1-22 AUTOMATIC TRANSMISSION (4 A/T)
Table B-1 : “O/D OFF” Light Circuit Check (“O/D OFF” Light Doesn’t Light at
Ignition Switch ON But Engine Starts Up)
WIRING DIAGRAM
TROUBLESHOOTING
1. PCM 4. P/N change switch
2. Fuse 5. J/C
3. O/D off switch 6. J/C
Step Action Yes No
1“O/D OFF” light circuit check:
1) With ignition switch OFF, disconnect cou-
plers from PCM.
2) Using service wire, connect E61-20 termi-
nal of disconnected PCM coupler and
ground.
Does “O/D OFF” light turn ON at ignition switch
ON?Poor E61-20 terminal con-
nection.
If OK, substitute a know-
good PCM and recheck.Bulb burned out or faulty
“WHT/BLK”, “BLK/WHT”
wire.
Page 433 of 656
7B1-24 AUTOMATIC TRANSMISSION (4 A/T)
Table B-3 : “POWER” Light Circuit Check (“POWER” Light Doesn’t Light at
Ignition Switch ON But Engine Starts Up)
WIRING DIAGRAM
TROUBLESHOOTING
1. PCM 4. P/N change switch
2. Fuse 5. J/C
3. O/D off switch
Step Action Yes No
1“POWER” light circuit check :
1) With ignition switch OFF, disconnect cou-
plers from PCM.
2) Using service wire, connect E61-21 termi-
nal of disconnected PCM coupler and
ground.
Does “POWER” light turn ON at ignition switch
ON?Poor E61-21 terminal con-
nection.
If OK, substitute a known-
good PCM and recheck.Bulb burned out or faulty
“GRY/BLU”, “BLK/WHT”
wire.