Suzuki 2000 Grand Vitara SQ625 Service Manual page 207

6-1-96 ENGINE (H25 ENGINE)
SYSTEM DESCRIPTION
EGR system consists of EGR valve and its passage. ECM (PCM) judges EGR valve opening based on following
items. (engine speed, engine load, engine coolant temperature, intake air temperature and vehicle speed)
If EGR system is in good condition, intake manifold absolute pressure is varied within specified value as soon as
ECM (PCM) opens EGR valve.
DTC DETECTING CONDITION AND TROUBLE AREA
DTC DETECTING CONDITION
The difference of intake manifold absolute pressure before and
after EGR valve is opened is out of specification.
DTC CONFIRMATION PROCEDURE
NOTE:
Check to make sure that following conditions are satisfied when using this DTC CONFIRMATION PROCE-
DURE.
WARNING:
D When performing a road test, select a place where there is no traffic or possibility of a traffic accident
and very careful during to avoid occurrence of an accident.
D Road test, should be carried out with 2 person, a driver and tester, on a level road.
D Intake air temperature: between –14 C and 70 C (6.8 F and 158 F)
D Atmospheric pressure: higher than 560 mmHg (Altitude: lower than 2790 m (9150 ft))
D Following DTC is not detected: P1408
(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 to 50 – 65 km/h (30 – 40 mph) (engine speed; 2000 – 3000 r/min.).
(5) Keep above vehicle speed for 3 min. (Throttle valve operating is kept constant in this step.)
(6) Stop vehicle and check DTC and pending DTC by using scan tool.
DTC TROUBLESHOOTING
STEP
1 Was "ENGINE DIAG. FLOW TABLE" performed?
2 Do you have SUZUKI scan tool?
3 EGR Valve Operation check:
(1) With ignition switch OFF, install SUZUKI scan tool.
(2) Check EGR system referring to "ENGINE AND
EMISSION CONTROL" section.
Is it in good condition?
4 EGR Valve Power Supply Circuit check:
( ) (1) With ignition switch OFF, disconnect EGR valve g
coupler (1).
(2) With ignition switch ON, check voltage between
C04-2 (b) and ground, C04-5 (e) and ground.
Is each voltage 10 – 14 V?
ACTION
TROUBLE AREA
EGR valve
EGR circuit
EGR system
MAP sensor
ECM (PCM)
YES
Go to Step 2.
Go to Step 3.
Intermittent trouble.
If OK, substitute a
known-good ECM
(PCM) and recheck.
Go to Step 5.
NO
Go to "ENGINE
DIAG. FLOW
TABLE".
Go to Step 4.
Go to Step 4.
Faulty "Bl/B" wire.