ECM SUZUKI GRAND VITARA 2001 2.G Manual Online

6-1-94 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0420 Catalyst System Efficiency Below Threshold (Bank 1)
SYSTEM DIAGRAM
CIRCUIT DESCRIPTION
Exhaust oxygen concentration at the pre-catalyst and the post-catalyst of WU-TWC is detected from HO2S-1
and HO2S-2 respectively and accordingly ECM (PCM) controls the closed loop which then controls the fuel
injection volume. (Refer to Section 6E2.) While the above control is going on and if WU-TWC is in good condi-
tion, the output voltage of HO2S-2 is maintained at specified level. As WU-TWC becomes deteriorated, even
when the above control is going on, the exhaust gas which has passed WU-TWC then passes HO2S-2 at the
exhaust oxygen concentration similar to that of the pre-catalyst without being oxygenated or converted. Thus,
waveforms of HO2S-1 and HO2S-2 output voltages become alike. ECM (PCM) judges deterioration of WU-TWC
by comparing waveforms of HO2S-1 and HO2S-2.
DTC DETECTING CONDITION AND TROUBLE AREA
1. HO2S-1 (Bank-1) 4. TWC
2. HO2S-2 (Bank-1) 5. ECM (PCM)
3. WU-TWC
DTC DETECTING CONDITION TROUBLE AREA
While running under conditions described for DTC CON-
FIRMATION PROCEDURE, output waveform of HO2S-1
becomes similar to that of HO2S-2.
(2 driving cycle detection logic)• Exhaust gas leakage
• Warm up three way catalytic converter
• Heated oxygen sensor – 2 or its circuit
•ECM (PCM)

6-1-96 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0430 Catalyst System Efficiency Below Threshold (Bank 2)
SYSTEM DIAGRAM
CIRCUIT DESCRIPTION
Exhaust oxygen concentration at the pre-catalyst and the post-catalyst of WU-TWC is detected from HO2S-1
and HO2S-2 respectively and accordingly ECM (PCM) controls the closed loop which then controls the fuel
injection volume. (Refer to Section 6E2.) While the above control is going on and if WU-TWC is in good condi-
tion, the output voltage of HO2S-2 is maintained at specified level. As WU-TWC becomes deteriorated, even
when the above control is going on, the exhaust gas which has passed TWC then passes HO2S-2 at the
exhaust oxygen concentration similar to that of the pre-catalyst without being oxygenated or converted. Thus,
waveforms of HO2S-1 and HO2S-2 output voltages become alike. ECM (PCM) judges deterioration of WU-TWC
by comparing waveforms of HO2S-1 and HO2S-2.
DTC DETECTING CONDITION AND TROUBLE AREA
1. HO2S-1 (Bank-2) 4. TWC
2. HO2S-2 (Bank-2) 5. ECM (PCM)
3. WU-TWC
DTC DETECTING CONDITION TROUBLE AREA
While running under conditions described for DTC CON-
FIRMATION PROCEDURE, output waveform of HO2S-1
becomes similar to that of HO2S-2.
(2 driving cycle detection logic)• Exhaust gas leakage
• Warm up three way catalytic converter
• Heated oxygen sensor – 2 or its circuit
•ECM (PCM)

6-1-98 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0443 Evap Control System Purge Control Valve Circuit Malfunction
SYSTEM/WIRING DIAGRAM
DTC DETECTING CONDITION AND TROUBLE AREA
DTC CONFIRMATION PROCEDURE
1. Main fuse 3. EVAP canister purge valve
2. Main relay 4. ECM (PCM)
DTC DETECTING CONDITION TROUBLE AREA
Monitor signal of EVAP canister purge valve is different
from command signal. (Circuit open or short)
(2 driving cycle detection logic)• EVAP canister purge valve and its circuit
•ECM (PCM)
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.
NOTE:
Check to make sure that following condition is satisfied when using the “DTC Confirmation Proce-
dure.”
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)

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-99
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.
3) Start engine and warm up it completely.
4) Increase vehicle speed to 55 km/h (35 mph) or more.
5) Keep driving above vehicle speed for 20 min or more (Change of vehicle speed is permitted in this step).
6) Release accelerator pedal, stop vehicle and run engine at speed for 2 min.
7) Check DTC and pending DTC by using scan tool.
TROUBLESHOOTING
Step Action Yes No
1 Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE” in this
section.
2 Check EVAP canister purge system for opera-
tion referring to “EVAP CANISTER PURGE
SYSTEM INSPECTION” in this section.
Is check result satisfactory?Intermittent trouble or
faulty ECM (PCM).
Check for intermittent
referring to “INTERMIT-
TENT AND POOR CON-
NECTION” in Section 0A.Go to Step 3.
3 Check EVAP canister purge valve for resistance
referring to “EVAP CANISTER PURGE VALVE
INSPECTION” in this section.
Is resistance as specified?“GRN/BLK” or “BLU/BLK”
circuit open or short.
If wire and connections
are OK, substitute a
known-good ECM (PCM)
and recheck.Replace EVAP canister
purge valve.

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-103
DTC P0460 Fuel Level Sensor Circuit High Input
WIRING DIAGRAM/CIRCUIT DESCRIPTION
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 for 1 min.
3) Check pending DTC by using scan tool.
1. Fuel level sensor
2. Fuel meter in combination meter
3. ECM (PCM)
DTC DETECTING CONDITION TROUBLE AREA
Fuel level sensor output voltage higher than specified
value is detected for specified time.
(2 driving cycle detection logic)•Fuel level gauge or its circuit
•Fuel level sensor or its 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)

6-1-104 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
TROUBLESHOOTING
Step Action Yes No
1Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE” in this
section.
2 Does fuel level meter in combination meter indi-
cate “E” (Empty)?Replenish fuel tank with
fuel and go to Step 3.Go to Step 3.
3 Check fuel level sensor and its circuit:
1) Check voltage between terminal E61-28 and
ground with ignition switch ON.
Is it about 7.1 V or more?Go to Step 4. Intermittent trouble or
faulty ECM (PCM).
Check for intermittent
referring to “INTERMIT-
TENT AND POOR CON-
NECTION” in Section
0A.
4 Is voltage in Step 3 “9 – 14 V”?“BLU/WHT” wire shorted
to power circuit or fuel
level meter malfunction.Go to Step 5.
5 Check Fuel Level Sensor:
1) Turn ignition switch OFF and disconnect fuel
level sensor connector (L15 – R01).
2) Check for proper connection to fuel level
sensor at L15-4 and L15-3 terminals.
3) If OK, then check resistance between R01-4
and R01-3 terminals. (Refer to “FUEL LEVEL
GAUGE (SENDER GAUGE)” in Section 8C.)
Is value close to one of above values indicated?“BLU/WHT” or “BLK/YEL”
circuit open.
If wire and connection are
OK, substitute a known-
good ECM (PCM) and
recheck.Check “BLU/WHT” and
“BLK/YEL” wires
between R01 and R02
connections.
If OK, replace fuel level
sensor.

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-105
DTC P0500 (DTC No.24) Vehicle Speed Sensor Malfunction
WIRING DIAGRAM
DTC DETECTING CONDITION AND TROUBLE AREA
1. Speedometer
2. Vehicle speed sensor
3. Cruise control module (if equipped)
4. ECM (PCM)
DTC DETECTING CONDITION TROUBLE AREA
Vehicle speed signal not inputted although fuel is kept
cut for longer than 5 seconds
(2 driving cycle detection logic)•Vehicle speed sensor circuit open or short
•Vehicle speed sensor
•Vehicle speed sensor drive gear or driven gear
•Speedometer malfunction
•Cruise control module malfunction (if equipped)
•ECM (PCM)

6-1-106 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
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 warm up
engine completely.
3) Increase vehicle speed to 100 – 110 km/h (60 – 70 mph).
4) Release accelerator pedal and with engine brake applied, keep vehicle coasting for 5 seconds or more and
then stop vehicle.
5) Check pending DTC by using scan tool.
TROUBLESHOOTING
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.
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” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE” in this
section.
2 Does speedometer indicate vehicle speed? Faulty “BLU/YEL” wire or
poor C51-1-14 connection.
If wire and connection are
OK, intermittent trouble or
faulty ECM (PCM).
Check for intermittent refer-
ring to “INTERMITTENT
AND POOR CONNECTION”
in Section 0A.Go to Step 3.
3 VSS power supply voltage check:
1) With ignition switch OFF, remove VSS
coupler.
2) With ignition switch ON leaving engine
OFF, check voltage between C20-3 and
C20-2 terminal of VSS coupler.
Is voltage 10 – 14 V?Go to Step 4.“BLK/BLU” or “BLK/YEL”
wire open/short.
4 VSS signal harness check:
1) With ignition switch ON leaving engine
OFF, check voltage between C20-1 and
C20-2 terminal of VSS coupler.
Is voltage 4 V or more?Go to Step 5. Go to Step 6.

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-107
[A] Fig. for Step 3 / [B] Fig. for Step 4, 6, 7
Fig. for Step 55 VSS visual inspection:
1) Remove VSS referring to “TRANSFER”
section.
2) Check VSS drive and driven gears for
damage and excessive wear.
Are they in good condition?Poor VSS connection or VSS
malfunction.
If connection is OK, substi-
tute a known-good VSS and
recheck.Replace VSS.
6 Speedometer circuit check:
1) With ignition switch OFF, disconnect
G11 coupler from combination meter.
2) With ignition switch ON leaving engine
OFF, check voltage between C20-1 and
C20-2 terminal of VSS coupler.
Is voltage 4 V or more?Substitute a known-good
combination meter and
recheck.Go to Step 7.
7 Cruise control module circuit check (if
equipped):
1) With ignition switch OFF, disconnect
E132 coupler from cruise control mod-
ule.
2) With ignition switch ON leaving engine
OFF, check voltage between C20-1 and
C20-2 terminal of VSS coupler.
Is voltage 4 V or more?Substitute a known-good
cruise control module and
recheck.“BLU/YEL” wire open/
short or faulty ECM
(PCM).
If wire and connection are
OK, substitute a known-
good ECM (PCM) and
recheck.
1. VSS coupler
2.“BLU/YEL” (C20-1) terminal
3.“BLK/YEL” (C20-2) terminal
4.“BLU/BLK” (C20-3) terminal
Step Action Yes No
1. VSS coupler
2. VSS driven gear
3. VSS drive gear

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