Suzuki 2000 Grand Vitara SQ625 Service Manual page 100

6-96 ENGINE DIAGNOSIS (G16 / J20 ENGINES)
DTC P1450 BAROMETRIC PRESSURE SENSOR CIRCUIT MALFUNCTION
DTC P1451 BAROMETRIC PRESSURE SENSOR PERFORMANCE PROBLEM
SYSTEM DESCRIPTION
Barometric pressure sensor is installed in ECM (PCM).
DTC DETECTING CONDITION AND TROUBLE AREA
DTC DETECTING CONDITION
DTC P1450:
Barometric pressure out of specification is detected.
DTC P1451:
While running under conditions described for DTC
CONFIRMATION PROCEDURE, barometric pressure
value compared with intake manifold vacuum value in
fuel cut state is not as specified.
(DTC P1451: 2 driving cycles detection logic)
DTC CONFIRMATION PROCEDURE (DTC P1450)
1) Connect scan tool to DLC with ignition switch OFF.
2) Turn ON ignition switch and clear DTC by using scan tool and run engine for 1 min.
3) Check DTC and pending DTC by using scan tool.
DTC CONFIRMATION PROCEDURE (DTC P1451)
WARNING:
D When performing a road test, select a place where there is no traffic or possibility of a traffic accident
and be very careful during testing to avoid occurrence of an accident.
D Road test should be carried out with 2 persons, a driver and a tester, on a level road.
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 to normal operating temperature.
3) Increase engine speed to 3,000 r/min. in 3rd gear in case of M/T and "2" range in case of A/T.
4) Release accelerator pedal and with engine brake applied, keep vehicle coasting for 5 sec. or more. (Keep fuel
cut condition for 5 sec. or more) If fuel cut condition is not kept for 5 sec. or more, coast down a slope in engine
speed 1600 – 3000 r/min for 5 sec. or more.
5) Stop vehicle and run engine at idle.
6) Repeat steps 3) X 5) 2 times.
7) Check DTC and pending DTC by using scan tool.
TROUBLESHOOTING (DTC P1450/P1451)
STEP
1 Was "ENGINE DIAG. FLOW TABLE" performed?
2 Is DTC P1451?
3 MAP Sensor Check:
1) Check MAP sensor and its circuit referring to Steps 2
and 3 of DTC P1408 Diag. Flow Table.
Is check result satisfactory?
ACTION
TROUBLE AREA
D Barometric pressure sensor in ECM (PCM)
D Manifold absolute pressure sensor performance
problem
D Barometric pressure sensor in ECM (PCM)
YES
Go to Step 2.
Go to Step 3.
Substitute a known-
good ECM (PCM)
and recheck.
NO
Go to "ENGINE
DIAG. FLOW
TABLE".
Substitute a known-
good ECM (PCM)
and recheck.
MAP sensor or its
circuit malfunction.