Oil Pressure SwitchOil Pressure
Testing
Remove the YEL/RED wire from the engine oil pres-
sure swrtcn.
Check for continuity between the positive terminal
and the engine {ground). There should be continuity
with the engine stopped. There should be no conti-
nuity with the engine running.
L
PRESSURE SWTCH18 N.m {1.8 kgf.m,13 tbr.ftlApply liquid sealantto the threads,
lf the switch fails
level. lf the engine
orl pressure.
to operate, check the engine oil
oil level is OK, check the engine
Testing
lf the oil pressure warning light stays on with the engine
running, check the engine oil level. lf the oil level is cor-
rect:
L Connect a tachometer.
2. Remove the engine oil
an oil pressure gauge.
ADAPTER(1/8" - 28, BSTP)(Commercially available)
pressure switch. and install
OIL PRESSURE GAUGE
{Commercially available)
4.
ENGINE OIL PRESSURESWTTCH MOUNNNGHOt-E
Start the engine. Shut it off immedjately if the gauge
registers no oil pressure. Repair the problem before
continuing.
Allow the engine to reach operating temperature (fan
comes on at least twice). The pressure should be:
Engino Oil Temperature: 176'F (80'C)
Engine Oil Pressure:
At ldle:70 kPa (0.7 kgt/cm' , 10 psil
minimum
Ai 3,000 rpm: 3/r0 kPa {3.5 kgt/cm', 50 psi)
minimum
lf oil pressure in not within specifications, inspect the
oil pump (see page 8-9).
8-7
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Testing
Replace the thermostat if it is open at room temperature.
To test a closed thermostat:
1. Suspend the thermostat in a container of water. Do
not let the thermometer touch the bottom of the hot
container.
THERMOMETER
THERMOSTAT
Heat the water, and check the temperature with a
thermometer. Check the temperature at which the
thermostat first opens, and at which it is fully open.
Measure the lift height of the thermostat when fully
open.
STANDARD THERMOSTAT
Lift height: above 8.0 mm (0.31 in)
Starts opening: 169 - 176'F (76 - 80'C)
Fully open: 194'F (90'C)
10-9
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Fan Control
Fan Motor Testing
1. Disconnect the 2P connector.
Terminalside ofmale terminals
Test the motor by connecting battery power to theNo. 2 terminal and ground to the No. 1 terminal.
lf the motor fails to run or does not run smoothly,reptace rt.
RADIATOR FAN MOTOR
10-14
Radiator Fan Switch Testing
E@ Removing the radiator fan switch whilethe engine is hot can cause the coolant to spray out, seri-ously scalding you. Always let the enginc and radiatorcool down before removing the radiator fan switch.
1. Remove the radiator fan switch from the thermostathousing (see page 10 '10).
2. Suspend the radiator fan switch in a container ofwater as shown.
Heat the water, and check the temperature with athermometer. Do not let the thermometer touch thebottom of the hot container.
Measure the continuity between the A and B termi-nals according to the table.
Bleed the air from the cooling system after installingthe radiator fan switch (see page 10-5).
Terminal
op".*i- Tr"ip".a*" \.B
SWITCH
ON196 - 203"F
{91 - 95.C)o---o
OFF
5 - 14"F (3 - 8.C)
lower than the tem-peratu re wh en itgoes on
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Goolant Temperature Gauge
Gauge Testing
1. Check the No. 25 (7.5 A) fuse in the under-dash
fuse/relay box before testin9.
2. Make sure the ignition switch is OFF, then discon-
nect the YEL/GRN wire from the coolant tempera-
ture sending unit. and ground it with a jumper wire.
YEL/GRNWIRE
Turn the ignition switch ON {ll). Check that the
pointer of the coolant temperature gauge starts
moving toward the "H" mark. Turn the ignition
switch OFF before the pointer reaches "H" on the
gauge dial. Failure to do so may damage the gauge.
lf the pointer of the gauge does not move at all,
check for an open in the YEL/GRN wire.
lf the wires are OK, replace the coolant temperature
gauge.
lf the coolant temperature gauge works, test the
coolant temperature sending unit.
5.
COOLANT TEMPERATURE
Coolant Temperature Sending Unit
Testing
1. Disconnect the YEUGRN wire from the coolant tem
perature sending unit.
COOLANT TEMPERATURE
POSITIVETERMINAL
YEL/GRN WIRE(Covered withinsulation)
2. Using an ohmmeter, measure the change in resis-
tance between the positive terminal and the engine
(ground) with the engine cold and with the engine
at operating temPerature.
Temperature133.F (56'C)1A5 - 212F
(8s - 100'c)
Resistance(0)13746-30
3. lf the readings are substantially different from the
specitications above, inspect the coolant level and
the cooling system. lf the cooling system is OK,
replace the sending unit.
10-15
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Electrical Connections -'97 Model
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O No. 2s METER (7.5A)(D NO. 'I5 ALTERNATOR SP SENSOB (7.5A) *
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(cont'd)
1 1-15
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Troubleshooting
Troubleshooting Procedures (cont'd)
lf the inspection for a particular code requires voltage or resistance checks at the EcM/pcM connectors, remove the rightkick panel. Unbolt the EcM/PcM. and connect the backprobe sets and a digital multimeter as described below, check thesystem according to the procedure described for the appropriate code(s) listed on the following pages.
How to Us6 tho Backprobe S6ts
Backp.obo Adapto.
BACKPROBE SET
connect the backprobe adapters to the stacking patch cords. and connect the cords to a multimeter. Using the wire insula-tion as a guide for the contoured tip of the backprobe adapter, gently slide the tip into the connector from the wire sideuntil it comes in contact with the terminal end of the wire.
DIGITAI. MULTIMETER(Commarci.lly rvrilabl.l orKS-AHM-32-@3
@@)@)c,
11-62
o'SAZ - (xtlqDA lTwo requir.dl
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ECM/PCM Data
By connecting the OBD ll scan tool or the Honda PGM Tester to the 16P data link connector (OLC), various data can be
retrieved from the ECM/PCM. The items listed in the table below conform to the SAE recommended practice
The Honda PGM Tester also reads data beyond that recommended by SAE.
understanding this data will help to find the causes of intermittent failures or engine problems.
NOTE:
The ',operating values" given below are approximate values and may be different depending on the environment and
the individual vehicle.
Unless noted otherwise. "at idle speed" means idling with the engine completely warmed up, transmission in position
Park or neutral and the A,./C and all accessories turned otf.
DataDesc.iptionOp€rating ValuoFreeze Data
Diagnostic
Trouble Code
(DTC)
lf the ECM/PCM detects a problem, it will store it as a
code consisting of one letter and tour numbers
Depending on the problem, an SAE-defined code (Poxxx)
or a Honda-defined code (P'lxxx) will be output to the
tester.
lf no problem is detected,
there is no output.
YES
Engine SpeedThe ECN4/PCN4 computes engine speed from the signals
sent from the Crankshaft Position sensor.
This data is used for determining the time and amount of
fuel iniection.
Nearly the same as
tachometer indication
At idle speed:'97 - 98 models:
750 t 50 rpm'99 - 00 models:
730 f 50 rpm
YES
Vehicle SpeedThe ECM/PCM converts pulse signals from the Vehicle
Speed Sensor (VSSI into speed data.
Nearly the same as
speedometer indicationYES
Manifold
Absolute
Pressure (MAP)
The absolute pressure caused in the intake manifold by
engine load and speed.
With engin6 stopped:
Nearly the same as atmo-
spheric pressure
At idle speed:
2a - 41 kPa {210 - 310
mmHg, 8.3 - 12.2 inHg)
YES
Engine Coolant
Temperature
{ECT)
The ECT sensor converts coolant temperature into volt-
age and signals the ECM/PCM. The sensor is a thermistor
whose internal resistance changes with coolant tempera-
ture. The ECM/PCM uses the voltage signals from the
ECT sensor to determine the amount of injected fuel
With cold engine:
Same as ambient temPer-
ature and IAT
With engine warmed uP:
approx. 163 - 2'12'F
(73 - 100"c)
YES
Heated Oxygen
Sensor (HO25)
(Primary,
Sensor 1)
(Secondary
Sensor 2)
The Heated Oxygen Sensor detects the oxygen content in
the exhaust gas and sends voltage signals to the
ECMiPCM. Based on these signals, the ECM/PCM controls
the airlfuel ratio. When the oxygen content is high (that is.
when the ratio is leaner than the stoichiometric ratio), the
voltage signal is lower.
When the orygen content is low (that is, when the ratio
is richer than the stoichiometric ratio), the voltage signal
is higher.
0.0 - 1.25 V
At idle speed:
about 0.1 - 0.9
NO
(cont'd)
1 1-65
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Fuel Cut-off Control
. During deceleration with the throttle valve closed, current to the fuel injectors iscutoffto improvefuel economyat
speeds over 970 rpm ('97 - 98 models), 920 rpm ('99 - 00 modelsl.
. Fuel cut-off action also takes place when engine speed exceeds 6,500 rpm ('97 - 98 models), 6900 rpm ('99 - 00
models), regardless of the position of the throttle valve, to protect the engine from over-rewing.
With Ay'T model. the PCM cuts the fuel at engine speeds over 5,000 rpm when the vehicle is not moving.*'
4,./C Comoressor Clutch Relav
When the ECM/PCM receives a demand for cooling from the air conditioning system, it delays the compressor from
being energized, and enriches the mixture to assure a smooth transition to the Ay'C mode.
Evaporative Emission (EVAP) Purge Control Solenoid Valve
When the engine coolant temperature is above 154"F (68'C), the ECM/PCM controls the EVAP purge control solenoid
valve which controls vacuum to the EVAP purge control canister,
Alternator Control
The system controls the voltage generated at the alternator in accordance with the electrical load and driving mode.
which reduces the engine load to improve the fuel economy.
PCM Fail-saf e/Back-up Functions
1. Fail-safe Function
When an abnormality occurs in a signal from a sensor, the ECM/PCM ignores that signal and assumes a pre-pre
grammed value for that sensor that allows the engine to continue to run.
2. Back-up Function
When an abnormality occurs in the ECM/PCM itself, the fuel injectors are controlled by a back-up circuit independent
of the system in order to permit minimal driving.
3. Self-diagnosis Function IMalfunction Indicator Lamp (MlL)l
When an abnormality occurs in a signal from a sensor, the ECM/PCM supplies ground for the MIL and stores the DTC
in erasable memory. When the ignition is initially turned on {ll), the ECM/PCM supplies ground for the MIL for two
seconds to check the MIL bulb condition.
4. Two Trio Detection Method
To prevent false indications, the Two Trip Detection Method is used for the HO2S*1, fuel metering-related. idle control
system, ECT sensor and EVAP control system self-diagnostic functions. When an abnormality occurs, the ECM/PCM
stores it in its memory. When the same abnormality recurs after the ignition switch is turned OFF and ON (ll) again,
the ECM/PCM informs the driver by lighting the MlL. However, to ease troubleshooting, this function is cancelled
when you jump the service check connector, The MIL will then blink immediately when an abnormality occurs.
5. Two (or Three) Driving Cycle Detection Method {'97 model)
A "Driving Cycle" consists of starting the engine, beginning closed loop operation, and stopping the engine. lf misfir-
ing that increases emissions or EVAP control system malfunction is detected during two consecutive driving cycles.
or TWC deterioration is detected during three consecutive driving cycles, the ECM/PCM turns the MIL on. However, to
ease troubleshooting, this function is cancelled when you jump the service check connector. The MIL will then blink
immediately when an abnormality occurs.
*1: '97 - 98 models*2: '99 - 00 models
5.
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