Suzuki Engine 2002 GRAND VITARA SQ420 Service Manual page 203

6-1-62 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE)
DTC CONFIRMATION PROCEDURE
NOTE:
Check to make sure that following conditions are satisfied when using this DTC CONFIRMATION PRO-
CEDURE.
WARNING:
• When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and very careful during to avoid occurrence of an accident.
• Road test, should be carried out with 2 person, a driver and tester, on a level road.
• Intake air temperature : between –14°C and 70°C (6.8°F and 158°F)
• Atmospheric pressure : higher than 560 mmHg (Altitude : lower than 2790 m (9150 ft))
1) With ignition switch OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC by using scan tool if any.
3) Start engine and run it for 10 sec.
4) Check DTC by using scan tool.
DTC TROUBLESHOOTING
Step
1 Was "Engine Diag. Flow Table" performed?
2 MAF Sensor Power Supply Voltage check :
1) With ignition switch OFF, disconnect MAF
sensor coupler (1).
2) With ignition switch ON, check voltage
between "BLU/BLK" wire terminal (2) of
MAF sensor coupler and ground.
Is voltage 10 – 14 V?
3 MAF Sensor Output Voltage check :
1) With ignition switch OFF, connect MAF sen-
sor coupler.
2) Remove ECM (PCM) cover.
3) With ignition switch ON leaving engine OFF,
check voltage between C51-3-23 and C51-
3-21 terminal.
Is voltage 0.5 – 1.0 V?
Fig. for Step 2
Action Yes
Go to Step 2.
Go to Step 3.
Poor C51-3-23 or/and
C51-3- 21 terminal con-
nection.
If OK, substitute a known-
good ECM (PCM) and
recheck.
No
Go to "Engine Diag. Flow
Table".
Faulty "BLU/BLK" wire.
Faulty "PPL/WHT" wire
and "GRY/YEL" wire.
Poor MAF sensor coupler
terminal connection.
If wire and connection are
OK, substitute a known-
good MAF sensor and
recheck.