1999 HONDA CIVIC engine fan

Ground-to-Components I ndex
f.,lONOTE: All ground wires are BLK unless otherwise noted.
GroundPageComponents or Circuit Grounded
Battery (BLKYEL)
Steering pump bracket
t+-rg ITransmission housing
l
G101
(-1)
G101
(-2)
14-2
and
14-3
ano
14-1
Powertrain or engine control module (PG1 and pG2 are BLK: LG1 and LG2 are
BRN/BLK), EGR control solenoid valve (CW, EGR valve and lift sensor (Dt6yS enginewith M,/T), Engine coolant temperature switch, pGM-Fl main relay, power steeringpressure switch (USA), Primary HO2S (D16Y5 engine with l\/,/T), Vehicle speed sensor,VTEC pressure switch (D16Y5/D16Y8 engines), CKF sensor (BRN/BLK), Transmission
control module (CYf) (Pc1 is BLK: LG1 is BRN/BLK)
Shielding betvveen the PCM or ECM and these components (all have BRN/BLK wires):
CKF sensor, TDC/CKP/CYP sensor. Primary and secondary heated oxygen sensors.
Knock sensor (CWDl6YB engine), Mainshaft speed sensor (AiT except CVT),
I Countershaft speed sensor (A/T except CVf)
Shielding between the TCM and these components (CVT) (all have BRN/BLK wires):
Drive pulley speed sensor, Driven pulley speed sensor, Secondary gear shaft
speed sensor
Powertrain or engine control module (PG1 and pG2 are BLK; LG1 and LGz are
BRN/BLK), EGR control solenoid valve (D16Y5 engine), EGR valve (Dt685), Engine
coolant temperature switch, Fuel pressure regulator shut-off solenoid valve (D1685),
PGM-FI main relay, Power steering pressure switch (USA), Vehicle speed sensor, VTECpressure switch (All except D16Y7 engine), CKF sensor (A

except 81642) (BRN/BLK)
Shielding between the PCM or ECM and these components (all have BRN/BLK wires):
CKF sensor, TDC/CKP/CYP sensor, Primary and secondary heated oxygen sensors,
Knock sensor (All except D16Y7 engine), i/ainshaft speed sensor (Arf except CW),
Countershaft speed sensor (A,/T except CVf), Drive pulley speed sensor (CW), Drivenpulley speed sensor (CVT), Secondary gear shaft speed sensor (CVf)
I Badiator fan motor, Right front parking/turn signat tight, Right headtight
G20214-4I Cruise control actuator, Left front parking/turn signal lights, Left headlight, Rear window
I washer motor, Windshield washer motor, Washer fluid level switch (,99-'00 Canada)
G401| +-o
and
14-7
Accessory power socket, Brake fluid level switch, Clutch interlock switch (M/T), Clutchswitch (lillT with cruise/D16Y5 engine with MfD, Combination wiper switch (Z wires),
Cruise control main switch, Cruise control unit, Dash lights brightness controller, Data
link connector, Daytime running lights control unit (Canada), Gauge assembly, Horn('96-'97 models), Integrated control unit, Interlock control unit (ArI), Keyless door lock
control unit ('99-'00 models with keyless), Moonroof close and open relays, Moonroof
switch, Park pin switch (A/r), Power window relay, Rear window defogger relay, Rear
window defogger switch ('96-'98 models), Steering lock, Stereo radio tuner (,96-,98
USA: LX, EX, and HX), Turn signal/hazard relay, Windshield wiper motor.....plus
everything grounded through G402
6-6

- How the Circuit Works
Battery voltage is supplied through tuse 56 to the
A,/C compressor clutch r€lay contacts at all times.
With the ignition switch in ON (ll), vollage is applied
to the coil of the A,/C compressor clutch relay
through fuse 17. When you push the A,/C switch
ON, and the heater fan switch is in position | , 2, 3,
or 4, a "ground" input is provided to the engine
control module (ECM) or powertrain control module
(PCM) through the l'lC thermostat and the l'lC
pressure switch.
The A,/C compressor clutch relay is grounded by the
engine control module (ECM) or powertrain control
module (PCM). When energized, the A'lC
compressor clutch relay allows battery voltage to
turn on the A,/C comDressor clutch.
The A,/C ON indicator light comes on when the A,/C
system is requested.
A,/C Thermostat
The A'lC thermostat is located on the evaoorator
housing. The A,/C thermostat turns off the A,/C
compressor clutch if the temperature at the
evaporator goes below 3'C (37'F). This prevents
condensation from freezing on the evaporator fins
and blocking the air delivery into the passenger
compartment. The blower motor will keep running
when the sensor turns off the comDressor.
A,/C Pressure Switch
The fuC oressure switch is located in the condenser
outlet line where refrigerant is in a high
temperature/high pressure liquid state. The switch
will sense abnormally high or low pressure, and
open the circuit. This removes ground, and the
compressor will stop running.
Thermal Protectot
The thermal protector, located on the A,/C
compressor, opens and turns the compressor off if it
senses high temperature. Once the compressor
cools, the switch will close and the compressor will
begin running again.
Refer to the Service Manual (Section 22,
Air Conditioning) for specific tests or
troubleshooting procedures.
62-3

Fans
- AllModels\,1 |
splicedtogetherinstead of inthe junctionconnector onDl6Y5 models
c211PHOTO 11
FANRELAYPrtofo 10
Se€ I'i CCompre€sorCont ols
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I ; I control | ;
I :L--J :I ' PoWERTRAIN ordu. ' ENGINE CONTROL '' MODULE
: (PCMoTECM) :I PHAfO 86I wEw 7allqA ----.ENGINECOOLANTTEMPERATUREswtrcH BLLPHO|O 33 ?
Ses GrolndDiskibution,oaqe 14.
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i:
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c7531
BLU/BLK
ALK2
BLK
RADIATORFANMOTORI
BLK
BLK1
ELK
c753
CONDENSERFANMOTOR
a
* czsr
page 14.
II
FJ'Glot
c211
Gro!nd
T
Se€ GroundOstribution,Pago 14.4"t1 - '96.f98: All models'99-'00: 016Y5 with M/I 01685"2 = '99-'00: Allmodels exceptD16Y5 with M/T and 01685
cof{oENs€R
* czor33123lCVIl
63

- How the Circuit Works
Radiator Fan
Voltage is provided at all times to the radiator fan
relay (contacts) through fuse 57. With the ignition
swilch in ON (ll), voltage is provided to the coil of
the relay through luse 17.
The radiator tan relay can be grounded through
either the engine coolant temperature switch or the
engine control module (ECM) or powertrain control
module (PCM).
The engine coolant temperature switch grounds
the radiator fan relay (coil) when the engine
coolant temperature exceeds 199'F (83'C). The
switch opens when coolanl temperature
decreases 3'- 8'C.
Condenser Fan
Voltage is provided at all times to the condenser fan
relay (contacts) through fuse 56. With the ignition
switch in ON (ll), voltage is provided to the coil of
the relay through fuse 17. When you push the A'lC
switch and put the heater fan switch in 1, 2,3, o( 4
position, the ly'C thermostat comes on, the
condenser fan relay energizes, and the condenser
fan motor runs.
A,/C Thermostat
The A,/C thermostat is located on the evaporator
housing. The A,/C thermostat tums off the A/C
compressor clutch if the temperature at the
evaporator goes below 3'C (37'F). This prevents
condensation from freezing on the evaporator fins
and blocking the air delivery into the passenger
compartment. lf the temperature goes below 3'C
(37"F) tuming off the Ay'C thermostat, ground will be
removed from the condenser fan relay. This will
deenergize the relay and remove voltage from the
condenser fan motor causing the fan to stop running.
Reter to the Service Manual (Section 23, Eleckical)
for specific tests or troubleshooting procedures.
63-3

Gauges (cont'd)
- How the Gircuit Works
When the ignition switch is in ON (ll) or START (lll),
battery voltage is supplied through fuse 25 to the
gauges in the gauge assembly.
Speedometer and Odometer
The odometer and soeedometer drive circuits
receive pulses from the vehicle speed sensor
(VSS). The pulse rate increases as the car
accelerates. The frequency and duration of these
input pulses are measured and displayed by the
speedometer, odometer and tripmeter.
Tachometer
The tachometer drive circuit receives pulses from
the ignition control module (lCM) in the distributor
assembly or the ECM/PCM. The solid-state
lachometer then displays these pulses as engine
speed. For each 200 pulses per minute from the
ignition control modul€ (lCM) or the ECM/PCM, the
tachometer displays 100 RPM.
Engine Coolant Temperature Gauge
The engine coolant temperature gauge has two
intersecting coils wound around a permanent
magnet rotor. Voltage applied to the coils, through
fuse 25, generates a magnetic lield. The magnetic
field, controlled by the coolant temperature sending
unit, causes the rotor to rotate and the gauge
needle to move. As the resistance in the sending
unit varies, current through the gauge coils
changes. The gauge needle moves toward the coil
with the strongest magnetic field.
The 6ngine coolant temperature sending unit's
resistance varies from about 137 ohms at low
engine temperature to between 3H6 ohms at high
temperature (radiator fan running).
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
81-2
(
Fuel Gauge (All except cX)
The fuel gauge has two intersecting coils wound
around a permanent magnet rotor. Voltage applied
to the coils, through tuse 25, generates a magnetic
field. The magnetic field, controlled by the fuel
gauge sending unit, causes the rotor to rotate and
the gauge needle to move. As the resislance in the
sending unit varies, current through the gauge coils
changes. The gauge needle moves toward the coil
with the strongest magnetic field.
The fuel gauge sending unit's resistance varies
from about 2-5 ohms at full, to about 110 ohms at
empty. When you turn the ignition switch off, the
gauge remains at the last reading until you turn the
ignition switch to ON (ll) or START (lll) again,
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
Fuel Gauge (GX)
The fuel gauge has two intersecting coils wound
around a permanent magnet rotor. Voltage applied
to the coils, through fuse 25, generates a magnetic
field. The magnetic field, controlled by the PCM,
causes the rotor to rotate and the gauge needle to
move. The PCM calculates the gas quantity in the
fuel tank by using the fuel pressure value detected
by the tuel tank pressure sensor and the fuel
temperature value detected by the fuel tank
temperalure sensor, and outputs the signal to the
gauge assembly. The gauge needle moves toward
the coil with the strongest magnetic field.
When you turn the ignition switch off , the gauge
remains at the last reading until you turn the ignition
switch to ON (ll) or START (lll) again. When the
PCM detects a malfunction with the fuel pressure or
temperature, or detects a gas leak, the PCM
reduces the fuel meter to 0.
Refer to the Service Manual GX Supplement
(Section 11 , Fuel and Emissions) for specific tests
or troubleshooting procedures.
a
a

-
Component Connector View Index (Views begin on page 202-21
Connector View
ABS Control Unit........ ......63
Audio Unit ('99-'00 models) ......74
Combination Light Switch . . . . . . . . . . . . . . . 64
Combination Wiper Switch . . . . . . . . . . . . . . 65
Cruise Control Unit.... .....43
C\TTTransmission Solenoid ............. 25
Data Link Connector (DLC) ..... 48
Daytime Runnlng Lights Control Unit ..... 66
Engine control Module (ECM) ...........70
Exhaust Gas Recirculation (EGR) Valve
and Lift Sensor (D16Y5 Mfl, D1685) . . . . 10
Gauge Assembly .............71
HazardWarnlngSwitch,,. .,,,...,,,,... 32
Heater Control Panel ('96-'98 models) .....44
Heater Control Panel ('99-'00 models) ...., 76
Heater Fan Switch ('96-'98 models) ,,,.... 11
fniector Control Module (GX) ............77
I/
202-1
Connector View
Integrated Control Unit .......,. 67
f nterfock Control Unit .... ...... 26
Keyfess Door Lock Control Unit . . . . , . . . . . 75
Mode Control Motor ... ........'17
Moonroof Close Relay .. .......13
Moonroof Open Relay ... .......15
PGM-FI Main Relay .. .......... 18
Power Door Lock Conlrol Unil ..... ...... 37
Power Mirror Switch .,... ...... 33
Power Window Master Switch .,.........36
Powertrain Control Module (PCM) .......70
Security Control Unit ..., ..,,... 58
Security Starter Cut Belay ... ...,,,....,, 12
SRS Unit ............. 51
Stereo Radio Tuner ('96-'98 models) ...... 68
Transmission Control Module CICM) .....69

\7. C604 (Hatchback)
GRN/BLK(Back-up lights)
l\4ale GRNIYELFemale - GRN/RED(Turn signaland hazardwarning lights)
BLK (G601)
- Gray- Left rear ol cargo area- Connects rear wire harness to left outer
taillight assembly
4
5
6
1
2
GRNAVHT(Brake lights)
FED/BLK(Headllght switch)
10. Exhaust Gas Recirculation
(EGR) Valve and Lift Sensor
1
2
3
(D16Y5 MfI D1685)
- Gray- Top right side of engine- On engine wire harness
WHT/BLK (EGR input)
GRN/BLK(Sensor ground)
YEUBLU(Reference voltage)
4
5
6
BLK (Ground)
PNK (EGR control)
of cargo area
rear wire harness to right outer
assembly
n- -n
a t | _ a2a
l3I4t5tttl
IJ
I
8. C605 (Hatchback)
- Gray- Right rear- Connects
taillight
GRN/BLK(Back-up lights)
GRNTYEL(Turn signaland hazardwarning lights)
3
4
5
6
1
2
BLK (G601)
GFNAVHT (Brake lights)
RED/BLK(Headlight switch)
11. Heater Fan Switch
('96-'98 Models)
- Brown
Center of dash- On heater-sub B wire harness
BLK (Ground)
BLUAVHT (L4edium
LO speed input)
BLU/BLK(Hl speed input)
4
5
6
1
2
3
BLU (LO speed input)
BLU/YEL (Medium
Hlspeed input)
GFIN (Blowerswitch ON input)
9. C607 (Hatchback)
- Blue- Right side o{ cargo area- On rear wire harness
BLU/BLK (lndicators)
RED/BLK(License lights)
GBN,ryVHT (8rake lights)
LT GBN(Rear wiper/washe0
5
6
1
2
3
4
GRN(Rear wiper/washer)
LT GRN/BLK(Rear \/iper washer)
)/
202-3
12. Security Starter Cut Relay/C416
- Natural* Upper left kick panel- On main wire harness
1
2Allexcept CX and DXI[,4ale: BLK,^r'r'HTFemale: BLKI/ELCX and DXi BLI(WHT(Battery input)
All except CX and DX:BLK^/ELCX and DX: BLK/WHT(Baftery input)
[.4ale - BLK/WHTFemale - BLKAVHTor BLKRED(Starter output)
All excepi CX and DX:RED/YELCX and DX: GRN(Security starter c!1relay control inpul)
5
6
tl3'

21. C214
- Gray- Right side of engine compartment- Connects engine wire harness to main wire harness
'96- 97 models:Male - WHT/GRNFemale - BLU/FED(Horn)'98-'00 models:BLU/RED (Horn)
BLKRED (Fans)
WHT (Fans)
4
5
6
7
*io t0,,"compressor controls)
BLU/RED (A,/C
compressor controls)
BLU,ryVHT (I'/C
compressor controls)
2
3
23. C639
- Black,ryVhite- Top front ot driver's door- Connects driver's door wire harness to driver's
power mirror pigtail
Without Defogger:
1
2
4
6 Male - LT GRNFema|e - BLU/BLK(Left/right control)
With Oelogger:
1
2
3 l\,lale - BLKAVHTFemale - BLK(Ground)
4 lvlale - BLU/REDFemale ORNAVHT(Delogge4
lvlale PNKFemale - YEURED(Common)
MaIe _ GRYFemale BLUA/VHT(Up/down control)
lvlale - LT GRNFemale BLU/BLK(Corrmon)
i.4ale - PNKFemale - YEURED(Up/down conkol)
Male - GRYFemale - BLU,ryVHT(Lett/right control)
22. C552
- Green- On rear of under-dash fuse/relay box- On tloor wire harness
1 *1: FEDA/VHT(Power windows)
2 *1: YEL/BLK(Power windows)
3 *1:YEL/BLK
(Power windows)
4 *1 | RED/WHT(Power windows)
*1= Sedan only*2='96''98:All'99-'00r GX
6
7
GRN/BLK(Power windows)
GRN/BLK(Power windows)*2: BLK/YEL(Power mifiors)
BLU/BLK
{Power windows)
202-6
24. C556
- Black,ryVhite- Top front of front passenger's door- Connects tront passengefs door wire harness
to passenger's power mirror pigtail
Without Defogger:
l
2
3 l\4ale -
Female BLK(Not Used)
4 l\4ale -
Female - ORN/WHT(Not Used)
With Delogger:
1
2
3 Male - BLK^VHTFemale - BLK(Ground)
4 l\.4ale - BLU/REDFemale - ORNAVHT(Defogger)
Male OBNFemale - YEUBLK(LefVright control)
l\4ale - PNKFemale - YEL/RED(Common)
Male BRNFemale - GRNA/VHT(Up/down conkol)
[.4ale - ORNFemale - YEL/BLK(Left/right control)
lrale - PNKFemale - YEURED(Up/down conkol)
l\,lale - BFNFemale'GFiN(Common)