Suzuki Engine 2002 GRAND VITARA SQ420 Service Manual page 265

6-1-124 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE)
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 warm up to normal operating temperature.
4) Increase vehicle speed till engine speed is reached 4000 r/min. in 3rd gear (M/T) or 2nd range (A/T).
5) Release accelerator pedal and with engine brake applied, keep vehicle coasting and then stop vehicle.
6) Check DTC by using scan tool.
DTC TROUBLESHOOTING
Step
1 Was "Engine Diag. Flow Table" performed?
2 Does speedometer indicate vehicle speed?
3 VSS Power Supply Voltage check :
1) Remove ECM (PCM) cover.
2) With ignition switch OFF, remove VSS cou-
pler (1).
3) With ignition switch ON leaving engine OFF,
check voltage between "BLU/BLK" wire ter-
minal (3) and "BLK/YEL" wire terminal (2) of
VSS coupler.
Is voltage 10 – 14 V?
4 VSS Signal Harness check :
1) With ignition switch ON leaving engine OFF,
check voltage between "BLU/YEL" wire ter-
minal (4) and "BLK/YEL" wire terminal (5) of
VSS coupler (6).
Is voltage 4 V or more?
5 VSS Visual inspection :
1) Remove VSS (7) referring to "Transfer" sec-
tion.
2) Check VSS drive gear (9) and driven gear
(8) for damage and excessive wear.
Are they in good condition?
Action Yes
Go to Step 2.
Faulty "BLU/YEL" wire,
poor C51-3-1 connection
or intermittent trouble.
If OK, substitute a known-
good ECM (PCM) and
recheck.
Go to Step 4.
Go to Step 5.
Poor VSS connection.
If OK, substitute a known-
good VSS and recheck.
No
Go to "Engine Diag. Flow
Table".
Go to Step 3.
Faulty "BLU/BLK", "BLK/
YEL" wire.
Go to Step 6.
Replace VSS.