2000 SUZUKI SWIFT check engine

6-92 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
Fig. 1 for Step 1
DTC P1450 BAROMETRIC PRESSURE SENSOR LOW / HIGH INPUT
DTC P1451 BAROMETRIC PRESSURE SENSOR PERFORMANCE PROBLEM
WIRING DIAGRAM / CIRCUIT DESCRIPTION
Barometric pressure sensor is installed in ECM (PCM).
DTC DETECTING CONDITION
POSSIBLE CAUSE
DTC P1450:

Barometric pressure: 136 kPa 1025 mmHg or higher, or
33 kPa 250 mmHg or lower
ECM (PCM) (barometric pressure sensor)
malfunction
DTC P1451:

Vehicle stopped.

Engine cranking.

Difference between barometric pressure and intake
manifold absolute pressure is 26 kPa, 200 mmHg or more.
2 driving cycle detection logic, monitoring once / 1 driving.
Manifold absolute pressure sensor and its
circuit malfunction

ECM (PCM) (barometric pressure sensor)
malfunction
DTC CONFIRMATION PROCEDURE
1) Turn ignition switch OFF.
2) Clear DTC with ignition switch ON.
3) Turn ignition switch ON for 2 sec., crank engine for 2 sec. and run it at idle for 1 min.
4) Check pending DTC in “ON BOARD TEST” or “PENDING DTC” mode and DTC in “DTC” mode.
INSPECTION
DTC P1450:
Substitute a known-good ECM (PCM) and recheck.
DTC P1451:
NOTE:
Note that atmospheric pressure varies depending on weather conditions as well as altitude.
Take that into consideration when performing these check.
STEP
ACTIONYESNO
11) Connect scan tool to DLC with ignition switch
OFF.
2) Turn ignition switch ON and select “DATA
LIST” mode on scan tool.
3) Check manifold absolute pressure. See Fig. 1.
Is it barometric pressure (approx. 100 kPa,
760 mmHg) at sea level?Substitute a known-
good ECM (PCM) and
recheck.Check intake manifold
pressure sensor and its
circuit.
Go to P0105 DIAG.
FLOW TABLE.

Main
fuse
M / T vehicle
Ignition
switch
(starter
switch)Starter
A / T vehicle
Main
fuse
Ignition
switch
(starter
switch)Transmission
range sensor (switch)
StarterPCM
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-93
DTC P1500 ENGINE STARTER SIGNAL CIRCUIT MALFUNCTION
CIRCUIT DESCRIPTION
DTC DETECTING CONDITIONPOSSIBLE CAUSE

High voltage at terminal C01-16 for 3 min. after engine
start.

Low voltage at terminal C01-16 during starting engine.
2 driving cycle detection logic, continuous monitoring.
“B/Y” circuit open

ECM (PCM) malfunction
DTC CONFIRMATION PROCEDURE
1) Turn ignition switch OFF.
2) Clear DTC with ignition switch ON, crank engine and run it at idle for 3 min.
3) Check pending DTC in “ON BOARD TEST” or “PENDING DTC” mode and DTC in “DTC” mode.
INSPECTION
STEPACTIONYESNO
1Was “ENGINE DIAG. FLOW TABLE” performed?Go to Step 2.Go to “ENGINE DIAG.
FLOW TABLE”.
2Check for voltage at terminal C01-16 of ECM
(PCM) connector connected, under following
condition.
While engine cranking : 6 – 10 V
After starting engine : 0 V
Is voltage as specified?Poor C01-16
connection or
intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection”
in Section 0A.
If wire and connections
are OK, substitute a
known-good ECM (PCM)
and recheck.“B/Y” circuit open.

To DLC
“DOME” Main
fuse
6-94 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
DTC P1510 ECM (PCM) BACK-UP POWER SUPPLY MALFUNCTION
CIRCUIT DESCRIPTION
Battery voltage is supplied so that diagnostic trouble code memory, values for engine control learned by ECM
(PCM), etc. are kept in ECM (PCM) even when the ignition switch is turned OFF.
DTC DETECTING CONDITION
POSSIBLE CAUSE

Low voltage at terminal C02-14 after starting engine.
“W” circuit open

ECM (PCM) malfunction
DTC CONFIRMATION PROCEDURE
1) Clear DTC, start engine and run it at idle for 1 min.
2) Select “DTC” mode on scan tool and check DTC.
INSPECTION
STEPACTIONYESNO
1Check for voltage at terminal C02-14 of ECM
(PCM) connector connected, under each
condition, ignition switch OFF and engine
running.
Is it 10 – 14 V at each condition?Poor C02-14
connection or
intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection”
in Section 0A.
If wire and connections
are OK, substitute a
known- good ECM
(PCM) and recheck.“W” circuit open.

“IG
COIL
METER”
Main
fuseIgnition
switch
Main
relayTo other circuits
Injector resistor Fuel injector
6-96 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
TABLE B-1 FUEL INJECTOR CIRCUIT CHECK
INSPECTION
STEPACTIONYESNO
1Was “ENGINE DIAG. FLOW TABLE” performed?Go to Step 2.Go to “ENGINE DIAG.
FLOW TABLE”.
2Injector Circuit Check
1) Check injector circuit for short.
Is fuel injected from injector at ignition switch ON?“Y/B” wire shorted to
ground or faulty
injector.
If wire and injector is
as specified
respectively and then
substitute known-
good ECM (PCM) and
recheck.Go to Step 3.
3Injector Check
1) Check injector for fuel Injection referring to FUEL
INJECTOR ON-VEHICLE INSPECTION in
Section 6E1.
Is fuel injected from injector at engine cranking?Go to Step 4.Go to Step 5.
4Injector Leakage Check
1) Check injector for leaks referring to FUEL
INJECTOR ON-VEHICLE INSPECTION in
Section 6E1.
Is it in good condition?Injector and its circuit
are in good condition.Faulty fuel injector.
5Check Injector for Operating Sound.
1) Using sound scope, check injector for operating
sound at engine cranking.
Is it detected?Proceed to DIAG.
FLOW TABLE B-2 and
B-3.Go to Step 6.

ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-97
STEPACTIONYESNO
6Check Injector Resistor for Resistance.
1) Disconnect resistor connector with ignition switch
OFF.
2) Check for proper connection to resistor at each
terminals.
3) If connection is OK, check resistance.
Is resistance 1.9 – 2.1 Ω (at 20C, 68F)?“W/Bl”, “Y/G” or “Y/B”
wire open or poor
C02-12 connection.
If wires and
connections are OK,
substitute a known-
good ECM (PCM) and
recheck.Replace resistor.

6-98 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
Main
fuseIgnition
switchTo other circuits
Main
relay
Fuel pump relay
Fuel pump
CAUTION: Check to make sure that connection is
made between correct terminals. Wrong connection
can cause damage to ECM (PCM), wire harness, etc.
TABLE B-2 FUEL PUMP AND ITS CIRCUIT CHECK
INSPECTION
STEPACTIONYESNO
1Was “ENGINE DIAG. FLOW TABLE” performed?Go to Step 2.Go to “ENGINE
DIAG. FLOW
TABLE”.
2Check Fuel Pump Control System for Operation. See Fig. 1.
Is fuel pump heard to operate for 2 sec. after ignition switch
ON?Fuel pump circuit
is in good
condition.Go to Step 3.
3Check Fuel Pump for Operation.
1) Remove fuel pump relay from relay box with ignition
switch OFF.
2) Check for proper connection to relay at each terminals.
3) If OK, using service wire, connect terminals E28-1 and
E28-2 of relay connector. See Fig. 2.
Is fuel pump heard to operate at ignition switch ON?Go to Step 4.“P”, “B” or “W/Bl”
circuit open or fuel
pump malfunction.
4Check Fuel Pump Relay for Operation.
1) Check resistance between each two terminals of fuel
pump relay. See Fig.3.
Between terminals “1” and “2”: Infinity
Between terminals “3” and “4”: 100 – 120 Ω
2) Check that there is continuity between terminals “1” and
“2” when battery is connected to terminals “3” and “4”. See
Fig. 4.
Is fuel pump relay in good condition?“P/W” circuit open
or poor C02-21
connection.
If wire and
connection are
OK, substitute a
known-good ECM
(PCM) and
recheck.Replace fuel pump
relay.

1. Fuel pump
2. Fuel filter
3. Throttle body
4. Fuel injector
5. Fuel pressure regulator6. Special tool
(Fuel pressure gauge &
3-way joint)
7. Fuel feed line
8. Fuel return line
6-100 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
TABLE B-3 FUEL PRESSURE CHECK
INSPECTION
STEPACTIONYESNO
1Check Fuel Pressure (Refer to Section 6E1 for details).
1) Release fuel pressure from fuel feed line.
2) Install fuel pressure gauge.
3) Check fuel pressure by repeating ignition switch
ON and OFF. See Fig. 1.
Is fuel pressure then 160 – 210 kPa (1.6 – 2.1 kg / cm
2,
22.7 – 29.9 psi)?
Go to Step 2.Go to Step 4.
2Is 90 kPa (0.9 kg / cm2, 12.8 psi) or higher fuel
pressure retained for 1 minute after fuel pump is
stopped at Step 1?Normal fuel pressure.Go to Step 3.
31) Start engine and warm it up to normal operating
temperature.
2) Keep it running at specified idle speed.
Is fuel pressure then within 90 – 140 kPa
(0.9 – 1.4 kg / cm
2, 12.8 – 20.0 psi)?
Normal fuel pressure.
Clogged vacuum
passage for fuel
pressure regulator
or

Faulty fuel pressure
regulator.
4Is there fuel leakage from fuel feed line hose, pipe or
their joint?Fuel leakage from
hose, pipe or joint.Go to Step 10.
5Was fuel pressure higher than specification in Step 1?Go to Step 6.Go to Step 7.
61) Disconnect fuel return hose from throttle body and
connect new return hose to it.
2) Insert the other end of new return hose into
approved gasoline container.
3) Operate fuel pump.
Is specified fuel pressure obtained then?Restricted fuel return
hose or pipe.Faulty fuel pressure
regulator.
7Was no fuel pressure supplied in Step 1?Go to Step 8.Go to Step 9.

ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-101
Fig. 1 for Step 1
1. Fuel pressure gauge & 3way joint
STEPACTIONYESNO
8With fuel pump operated and fuel return hose
blocked by pinching it, is fuel pressure applied?Faulty fuel pressure
regulator.Shortage of fuel or fuel
pump or its circuit
defective (refer to B-2
FUEL PUMP ANDITS
CIRCUIT CHECK).
91) Operate fuel pump.
2) With fuel return hose blocked by pinching it, check
fuel pressure.
Is it 450 kPa (4.5 kg / cm
2, 63.9 psi) or more?
Faulty fuel pressure
regulator.
Clogged fuel filter,

Restricted fuel feed
hose or pipe,

Faulty fuel pump or

Fuel leakage from
hose connection in
fuel tank.
101) Disconnect fuel return hose from throttle body and
connect new return hose to it.
2) Insert the other end of new return hose into
approved gasoline container.
3) Check again if specified pressure is retained.
While doing so, does fuel come out of return hose?Faulty fuel pressure
regulator.
Fuel leakage from
injector,

Fuel leakage from
between injector
and throttle body,

Faulty fuel pump
(faulty check valve
in fuel pump) or

Fuel leakage from
fuel pressure
regulator
diaphragm.