1998 HONDA CR-V cooling system

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.
www.emanualpro.com

Engine Goolant Temperature (ECTI Sensor
The scan tool indicates Diagnostic Trouble Code (DTC) P0116: A range/performance problem in the Engine
Coolant Temperature (ECT) Sensor circuit.
The ECT Sensor is a temperature dependant resistor (thermistor). The resistance of the thermistor decreases as the engine
coolant temperature increases as shown below
RESISTANCEtk0l
NOTE: lf DTC P0117 and/or P0118 are stored at the same
bleshoot DTC P0116.
Possible Cause
a ECT sensor deterioration
. Malfunction in the thermostat and cooling system
Troubleshooting Flowchart
-4 32 68 r0a r a0176 212 2aE {'r)-2O O 20 ito tO .o ! t2O I c)
ENGINE COOLANT TEMPERATURE
time as DTC P0116, troubleshoot those DTCS first, then trou-
THERMISTON
- The MIL has be€n roported on.- DTC P01'16 is stored.
Probl6m verification:1. Start the engine. Hold theengine at 3,000 rpm with noload (in Park or neutral) untilthe radiator fan comes on,then let it idle.2. With the scan tool, check theECT.
Intermittent failure, sYstem b OKat this tim6. Check lhe thermo-stat and the cooling 5y3tom.
ls 176 - 200'F (80 - 93"C) or0.4-0.TVindicated?
Check the thermostat and the
cooling system. It th€y are OK,reolace the ECT seNor.
(cont'd)
1 1-99
www.emanualpro.com

Air Conditioning Signal
This signals the EcM/PcM when there is a demand for cooling from the air conditioning system.
'97 modol:
Wire side of lemale terminals
PCM CONNECTOR C (31PI
ACS IBLU/RED)
PCM CONNECTOR A (:TIPI
(cont'd)
1 1-1 55
Chock for a shorl in thc wiro(ACS linol:1. Turn the ignition switch OFF.2. Disconnect the A/C pressure
switch 2Pconneclor.3. Turn the ignition switch ON (ll).,1. [Ieasu re voltage betweenPCM connector terminals C5
and A9.
Check for . .hon in the wire IAGSlinel:1. Turn the ignition switch OFF.2. Disconnect PCM connector C(31P).
3. Check for continuity betweenbody ground and PCM con-nector torminal C5.
Reoaii short in tho wire b€twoenrh6 PCM (Csl and the A/C pres-
3urc 3witch.
- Subcdtrte a known{ood PCMand recheck. lf pr6actibed volt-age is now av{ilable, roplacethe origind PCM,- Soe the eir conditionor in3p€c-lion lsee soction 221.
Check tor an opon in the wite(ACC lino):1. TLrrn the ignition switch OFF.2. Roconnect the A/C pressure
switch 2P connector.3. Turn the ignition switch ON (ll).
4. Momenta rily connect PCMconnector terminals A9 and417 with a iumper wire sev'eraltimes,
Wire side of female terminals
JUMPER WIRE
(To page 11-156)Wire side oI Iemale terminals
www.emanualpro.com

ldle Control System
Fast ldle Thermo Valve lA/T)
Description
To prevent erratic running when the engine is warming
up, it is necessary to raise the idle speed. The fast idle
thermo valve is controlled by a thermowax plunger.
When the engine is cold, the engine coolant surround-
ing the thermowax contracts the plunger, allowing addi-
tional air to be bvDassed into the intake manifold so that
the engine idles faster. When the engine reaches operat-
ing temperature. the valve closes, reducing the amount
of air bypassing into the intake manifold.
IDLEADJUSTING
IDLETHERMOVALVE
AIR BYPASS VALVE
11-168
Inspgction
NOTE: The fast idle thermo valve is factory adjusted; it
should not be disassembled.
1. Remove the intake air duct from the throttle body.
2. Start the engine,
3. Put your finger over the lower port in throttle body,
and make sure that there is air flow with the engine
cold (engine coolant temperature below 86"F, 30'C).
lf there is no air flow, replace the fast idle thermo
valve and retest,
O-RINGSReplace.
11.0 kgfl.m, 7.2 lbl.ftl
Start the engine. Hold the engine at 3,000 rpm with no
load (in Park or neutral) until the radiator fan comes
on, then let it idle.
Check that the valve is completely closed. lf the valve
is leaking, the idle speed will drop when you cover the
lower pon. Check the engine coolant level and for air
in the engine cooling system {see section 10). lf the
cooling system is OK, replace the fast idle thermo
valve and recheck.
www.emanualpro.com

Emission Control System
System Description
The emission control system includes, a Three Way
Catalytic Converter {TWC), Positive Crankcase Ventilation
(PCV) svstem and Evaporative Emission (€VAP) Control
system. The emission control system is designed to meet
federal and state emission standards.
Tailpipe Emission
Inspsction
!@ Do not smoke during this procsdura. Keep
any open tlame away from your work area.
1. Start the engine. Hold the engine at 3,000 rpm with
no load (in Park or neutral) until the radiator fan
comes on, then let it idle,
Connect a tachometer.
Check and, if necessary, adjust the idle speed, (see
page 11-169, 170).
Warm up and calibrate the CO meter according to the
meter manufacturer's instructions.
Check idle CO with the headlights, heater blower, rear
window defogger, cooling fan, and air conditioner off.
(Canada) Pull the parking brake lever up. Start the
engine, then check that the headlights are off.
CO meter should indicate 0.1% maximum.
4.
Three Way Catalytic Converter (TWCI
DsscriDtion
Three Way Catalytic Convertsr lTwcl:
The Three wav Catalvtic Converter (TWC) is used to
convert hydrocarbons (HC), carbon monoxide (CO), and
oxides of nitrogen (NOx) in the exhaust gas to carbon
dioxide (COr), dinitrogen (Nr) and water vapor,
{cont'd)
1 1-199
www.emanualpro.com

Troubleshooting
Symptom Ghart
For electrical malfunctions which are indicated by the self-diagnostic system, reter to selt-diagnosjs function (see next
page).
Note these items before troubleshooting a symptom.
. Check the engine coolant level, and allow the engine to warm up before troubleshooting.
. Anv abnormality must be corrected before continuing the test.
. Because of the precise measurements needed, use a digital multimeter with an output of 1 mA or less at the 20 kO
range when testing.
. Before performing any troubleshooting procedures check:
- Fuses No. 47 17.5 AJ, No. 55 (40 A), No. 56 (20 A), No. 57 (20 A) in the under-hood fuse/relay box, and No. 17 {7.5 A) in
the under-dash fuse/relay box.._ Grounds No. G101, G201, G202, G401, G4O2
- Cleanliness and tightness of all connectors
SymptomSse pags
Mode control motor does not run, or one or more modes are inoperative.
Recirculation control door does not change between Fresh and Recirculate.22-24
Radiator fan does not run at all (but condenser fan runs with the AVC on).
Condenser fan does not run at all {but radiator fan runs with the Ay'C on).22-29
Both fans (radiator and condenser) do not run for engine cooling. but they both run with the A,/C
on.
Both fans do not run with the Ay'C on22-33
Compressor clutch does not engage.22-34
AJC svstem does not come on (both fans and compressor).22-37
Both heater and A/C do not work,22-39
22-10
www.emanualpro.com

Radiator Fan Switch
RADIATOB FAN SWITCH 2P CONNECTOR
1
'.r
GRN
Wire side of female terminals
Both tans (radiator and condenser)do not run fo. engine cooling, butthey both run with the A/C on.
Check lor rn open in the wire:1. Disconnect the radiator fanswitch 2P connector.2. Turn the ignition switch ON lll).3, Measure the voltage betlveenthe No.2 terminal and bodygrou nd.
Repair open in the wire betweenthe radiator tan relay, the con-densei lan .elay and the radiaiortan swhch.
ls there battery voltage?
Chock for an open in the wire:1. Turn the ignition switch OFF.2. Check for continuity betweenthe No. 1 terminal of the radi-ator fan switch 2P connectorand body ground.
Check for an open in the wirebetween the .adialor fan switchand body glound. I ths wire is OF;choc* tor poor g.ound at G'101.
ls there continuity?
ls the cooling system OK?
Replsce the radialor fan switch.
www.emanualpro.com

4. Disconnect the heater hoses from the heater unit.
Engine coolant will run out when the hoses are dis-
connected; drain in into a clean drip pan.
CAUTION: Engino coolant will damage p8int. Ouickly
rinse any spill€d engine coolant Itom painted sur-
faces.
HEATER HOSEIOUTLET SIDE)
Remove the mounting nut from the heater unit.
Take care not to damage or bend the fuel lines, the
brake lines. etc.
CLAMPS
13 N.m 11.3 kg{.m,9.4 lbtftl
22-51
7.
ll.
Remove the dashboard (see section 20).
Remove the evaporator (see page 22-48).
Disconnect the connectors from the mode control
motor and the air mix control motor, and remove the
wire harness clips and wire harness from the heater
unit. Remove the clip from the heater duct, then
remove the mounting nuts and the heater unit
6x1.0mm9,8 N.m (1.0 kgt m,7.2lblft)
qInstall in the reverse order of removal. Make note of
the following items.
a
a
a
a
Apply sealant to the grommets.
Do not interchange the inlet and outlet heater
hoses. Make sure that the clamps are secure.
Refill the cooling system with engine coolant
{see section 10).
Adiust the heater valve cable (see page 22-53).
Make sure that there is no air leakage.
HEATER UNIT
www.emanualpro.com