1999 SUZUKI GRAND VITARA heater

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-71
Fig. for STEP 2, 34 HO2S heater control circuit check :
1) With ignition switch OFF, install HO2S
heater relay.
2) With ignition switch ON leaving engine OFF,
check voltage between C51-2-4 and
ground.
Is the voltage 10 – 14 V?Substitute a known-good
ECM (PCM) and recheck.Faulty HO2S heater relay
or “BLK” wire open, “BLU”
wire open or shorted to
ground circuit, “BLK/RED”
wire open or shorted to
ground circuit.
If OK, substitute a known-
good ECM (PCM) and
recheck. Step Action Yes No
a. HO2S heater relay

6-1-72 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0156 HO2S-2 (Bank 2) Circuit Malfunction
WIRING DIAGRAM
DTC DETECTING CONDITION AND TROUBLE AREA
DTC CONFIRMATION PROCEDURE
1. HO2S heater relay
2. ECM (PCM)
3. HO2S-2 (Bank-2)
DTC DETECTING CONDITION TROUBLE AREA
DTC will set when any one of following conditions is detected (2 driving
cycle detection logic).
• 4.5 V or more HO2S circuit voltage is detected when 5 V power is con-
nected to HO2S circuit in ECM (PCM).
• While running with A/F feed back, average output voltage during speci-
fied time is too high or too low.
or
• While running with A/F feed back, max output voltage during specified
time is lower than specified value or min. output voltage during speci-
fied time is higher than specified value.• HO2S-2 or its circuit
• Fuel system
• ECM (PCM)
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-73
1) Connect scan tool with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data in ECM memory by using scan
tool and start engine.
3) Increase vehicle speed to 55 km/h (40 mph) or more.
4) Keep driving above vehicle speed till engine is warmed up completely (Changed of vehicle speed is permit-
ted in this step).
5) Keep driving 50 – 60 km/h (30 – 40 mph) for 8 min. or more.
6) Stop vehicle and check if pending DTC exists by using scan tool. If not, check if oxygen sensor heater moni-
toring test has completed by using scan tool. If not in both of above checks (i.e., no pending DTC and oxy-
gen sensor heater monitoring test not completed), check vehicle conditions (environmental) and repeat
Steps 3) through 6).
TROUBLESHOOTING
NOTE:
Check to make sure that following conditions are satisfied when using this “DTC CONFIRMATION
PROCEDURE”.
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : – 8 – 110°C (18 – 230°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)
Step Action Yes No
1 Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE” in this
section.
2 HO2S-2 output voltage check :
1) Connect scan tool to DLC with ignition
switch OFF.
2) Drive vehicle about 35 mph, 55 km/h for 2
min. or more.
3) Stop vehicle and check HO2S-2 output volt-
age displayed on scan tool while repeating
racing engine.
Is over and below 0.3 V indicated?Go to Step 4. Go to Step 3.
3 HO2S-2 check :
1) With ignition switch OFF, disconnect HO2S-
2 coupler.
2) Connect voltmeter between “2” and “1” of
HO2S-2 coupler.
3) Start engine and check voltmeter while
repeating racing engine.
Is over and below 0.3 V indicated?“RED/YEL” or “GRY/YEL”
circuit open/short.
If wire and connection are
OK, substitute a known-
good ECM (PCM) and
recheck.Replace HO2S-2.
4 Short term fuel trim check :
1) Run engine at 2000 r/min. for 60 sec.
2) With engine idling, check short term fuel
trim displayed on scan tool.
Is it within – 20 to +20 %?Intermittent trouble or
faulty ECM (PCM).
Check for intermittent
referring to “INTERMIT-
TENT AND POOR CON-
NECTION” in Section 0A.Go to DTC P0174/P0175
Diag. Flow Table.

6-1-74 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0161 HO2S-2 (Bank 2) Heater Circuit Malfunction
WIRING DIAGRAM
Refer to DTC P0156.
DTC DETECTING CONDITION AND TROUBLE AREA
DTC CONFIRMATION PROCEDURE
1) Connect scan tool with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data in ECM memory by using scan
tool and start engine.
3) Increase vehicle speed to 50 – 60 km/h (30 – 40 mph).
4) Keep driving above vehicle speed for 5 min. (Change of vehicle speed is permitted in this step).
5) Stop vehicle and check if pending DTC exists by using scan tool. If not, check if oxygen sensor heater moni-
toring test has completed by using scan tool. If not in both of above checks (i.e., no pending DTC and oxy-
gen sensor heater monitoring test not completed), check vehicle conditions (environmental) and repeat
Steps 3) through 5).DTC DETECTING CONDITION TROUBLE AREA
Following condition is detected when HO2S-2 heater operates (2
driving cycle detection logic).
• Current of HO2S-2 heater is more than 11.4 A or less than 0.32 A,
or
• Voltage of HO2S-2 heater is more than 13.8 V or less than 8.7 V.HO2S-2 heater or its circuit
ECM (PCM)
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.
NOTE:
Check to make sure that following conditions are satisfied when using this “DTC CONFIRMATION
PROCEDURE”.
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : – 8 – 110°C (18 – 230°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-75
TROUBLESHOOTING
Fig. for STEP 2, 3Step Action Yes No
1 Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE” in this
section.
2 HO2S-2 heater check :
1) Disconnect HO2S-2 coupler with ignition
switch OFF.
2) Check resistance between “3” and “4” termi-
nal of HO2S-2 connector.
HO2S -2 heater resistance :
11.7 – 14.3
Ω
ΩΩ Ω (at 20°C (68°F))
Is it within above specificationGo to Step 3. Replace HO2S-2.
3 HO2S heater power supply check :
1) With ignition switch ON leaving engine OFF,
check voltage between E139-3 and ground,
E139-1 and ground. (See Fig.)
Is each voltage 10 – 14 V?Go to Step 4. Fuse “HO2S” and/or “IG
METER” blown.
If OK, faulty “BLK/WHT”
wire or “BLU/WHT” wire.
4 HO2S heater control circuit check :
1) With ignition switch OFF, install HO2S
heater relay.
2) With ignition switch ON leaving engine OFF,
check voltage between C51-2-17 and
ground.
Is the voltage 10 – 14 V?Substitute a known-good
ECM (PCM) and recheck.Faulty HO2S heater relay
or “BLK” wire open, “BLU”
wire open or shorted to
ground circuit, “PNK/
WHT” wire open or
shorted to ground circuit.
If OK, substitute a known-
good ECM (PCM) and
recheck.
a. HO2S heater relay

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-123
Table B-5 A/C Signal Circuits Inspection (If Equipped)
WIRING DIAGRAM
INSPECTION
1. A/C control module (amplifier)
2. ECM (PCM)
Step Action Yes No
1 Check A/C Signal Circuit.
1) Check voltage at terminal E61-17 with ignition
switch ON.
A/C signal circuit specification :
A/C switch and/or heater blower switch OFF (A/
C is not operating) : 10 – 14 V
Both A/C switch and heater blower switch ON :
0 – 1.5 V
Are check result as specified?Go to Step 2.“YEL/BLK” circuit open or
short, Evaporative tem-
perature is below 1°C
(34°F) or faulty A/C sys-
tem.
2 Check A/C Cut Signal Circuit.
1) Check voltage at terminal E61-8.
A/C cut signal specification :
While engine running and A/C switch and/or
heater blower switch OFF
(A/C is not operating) : 0 – 1.5 V
While engine running at idle speed and both A/
C switch and heater blower switch ON
(A/C is operating) : 10 – 14 V
Are check result as specified?A/C control signal cir-
cuits are in good con-
dition.“GRY/WHT” circuit open
or short, Poor perfor-
mance of ECT sensor, TP
sensor, Engine start sig-
nal inputted or A/C ampli-
fier malfunction.
If none of the above
exists, substitute a
known-good ECM (PCM)
and recheck.

6A2-4 ENGINE MECHANICAL (H27 ENGINE)
8) Disconnect accelerator cable (1) and A/T throttle cable (2)
(for A/T vehicle) from throttle body.
9) Disconnect water hoses (3) from throttle body.
10) Disconnect injector wire (1) coupler.
11) Disconnect brake booster hose (2) from intake manifold.
12) Disconnect couplers of TP sensor (1) and IAC valve (2).
13) Disconnect earth terminal (3) from intake collector.
14) Remove clamp bracket (4) from intake collector.
15) Disconnect couplers from manifold absolute pressure (MAP)
sensor, EVAP canister purge valve, earth terminal and EGR
valve.
16) Disconnect PCV hose from cylinder head cover.
Disconnect breather hoses from throttle body or cylinder
head cover.
17) Disconnect hoses of EVAP canister purge valve and heater.
18) Remove EGR pipe.
12
33
2
1
2
14
3
1. EVAP canister purge valve 6. PCV hose
2. EGR valve 7. Water hose
3. EGR pipe 8. Breather hose
4. EVAP canister purge valve hose 9. Earth terminal coupler
5. Heater hose
9
4
1 7
6
2
35
8

ENGINE MECHANICAL (H27 ENGINE) 6A2-5
19) Disconnect hoses of heater, EVAP canister, fuel feed and
fuel return.
20) Remove throttle body (1) and intake collector (2) from intake
manifold (3).
21) Disconnect hoses of PCV valve and EVAP canister purge
valve from intake collector.
22) Remove throttle body (1) from intake collector.
23) Remove EGR valve and EVAP canister purge valve from
intake collector.
24) Remove intake manifold bolts (8 pc.) and nuts (4 pc.).
25) Remove intake manifold.
1. Heater hose
2. Fuel feed hose
3. Fuel return hose
4. EVAP canister hose
13
2 4
1
3
2
1