Suzuki Engine 2002 GRAND VITARA SQ420 Service Manual page 205

6-1-64 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE)
• Intake air temperature : between –14°C and 70°C (68°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, clear DTC 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 Check IAT Sensor and Its Circuit.
1) Connect scan tool to DLC with ignition switch
OFF.
2) Turn ignition switch ON.
3) Check intake air temp. displayed on scan tool.
Is –40°C (–40°F) or 205°C (401°F) indicated?
3 Check Wire Harness.
1) Disconnect IAT sensor connector (1) with igni-
tion switch OFF.
2) Check for proper connection to IAT sensor at
"LT BLU" and "GRY/YEL" wire terminals.
3) If OK, then with ignition switch ON, is voltage
applied to "LT BLU" wire terminal about 4.5 –
5.5 V?
4 Does scan tool indicate –40°C (–40°F) at Step 2.
5 Check Wire Harness
1) Check intake air temp. displayed on scan tool
with ignition switch ON.
Is –40°C (–40°F) indicated?
6 Check Wire Harness.
1) Using service wire (2), connect IAT sensor con-
nector terminals.
2) Check intake air temp. displayed on scan tool
with ignition switch ON.
Is 205°C (401°F) indicated?
[A] Fig. for Step 3 / [B] Fig. for Step 6
Action Yes
Go to Step 2.
Go to Step 3.
Go to Step 5.
Go to Step 6.
Replace IAT sensor.
Replace IAT sensor.
No
Go to "Engine Diag. Flow
Table".
Intermittent trouble.
Check for intermittent
referring to "Intermittent
and Poor Connection" in
Section 0A.
"LT BLU" wire open or
shorted to power, or poor
C51-3-8 connection.
If wire and connection are
OK, substitute a known-
good ECM and recheck.
Go to Step 5.
"LT BLU" wire shorted to
ground.
If wire is OK, substitute a
known-good ECM and
recheck.
"LT BLU" wire open or
poor C51-3-21 connec-
tion.
If wire and connection are
OK, substitute a known-
good ECM and recheck.