LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Honda >> 2004 >> Civic GX >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Fuel System & Emissions System (GX) (Supplement) >> System Description >> Electronic Control System >> PCM Inputs and Outputs at Connector A (31P)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

PCM Inputs and Outputs at Connector A (31P)

Fig 1: Identifying Connector A (31P) Terminals
G04535989Courtesy of AMERICAN HONDA MOTOR CO., INC.
NOTE: Standard battery voltage is 12 V.
CONNECTOR A (31P) TERMINALS REFERENCE

Terminal number Wire color Terminal name Description Signal
1 BLK/WHT PO2SHTC (PRIMARY HEATED OXYGEN SENSOR (PRIMARY HO2S) HEATER CONTROL) Drives primary HO2S (Sensor 1) heater With ignition switch ON (II): battery voltage
With fully warmed up engine running: duty controlled
2 YEL/BLK IGP2 (POWER SOURCE) Power source for the PCM circuit With the ignition switch ON (II): battery voltage
With the ignition switch OFF: about 0 V
3 YEL/BLK IGP1 (POWER SOURCE) Power source for the PCM circuit With the ignition switch ON (II): battery voltage
With the ignition switch OFF: about 0 V
4 BLK PG2 (POWER GROUND) Ground for the PCM circuit Less than 1.0 V at all times
5 BLK PG1 (POWER GROUND) Ground for the PCM circuit Less than 1.0 V at all times
6 WHT PHO2S (PRIMARY HEATED OXYGEN SENSOR (PRIMARY HO2S), SENSOR 1) Detects primary HO2S sensor (sensor 1) signal With throttle fully opened from idle with fully warmed up
engine: about 0.6 V
With throttle quickly closed: below 0.4 V
7 BLU CKP (CRANKSHAFT POSITION (CKP) SENSOR) Detects CKP sensor signal With engine running: pulses
10 GRN/YEL SG2 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times
11 GRN/WHT SG1 (SENSOR GROUND) Sensor ground Less than 1.0 V at all times
12 BLK/RED IACV (IDLE AIR CONTROL (IAC) VALVE) Drives IAC valve With engine running: duty controlled
With ignition switch ON (II): about 5 V
14 BLK/WHT SO2SHTC (SECONDARY HEATED OXYGEN SENSOR (SECONDARY HO2S) (Sensor 2) HEATER CONTROL) Drives secondary HO2S (Sensor 2) heater With ignition switch ON (II): battery voltage
With fully warmed up engine running: duty controlled
15 RED/BLK TPS (THROTTLE POSITION (TP) SENSOR) Detects TP sensor signal With throttle fully open: about 4.8 V
With throttle fully closed: about 0.5 V
17 BRN/WHT INJ MODE (FUEL INJECTOR CURRENT CONTROL) Changes Injector driver mode. 5 V for 100 ms after turning ignition switch ON (II), then 0 V (intake air and/or fuel temperature below 0 °C)
18 BLU/WHT VEL2 (CVT SPEED SENSOR) Detects CVT speed sensor 2 Depending on vehicle speed: pulses when vehicle is stopped: about 0 V or 5 V
19 GRN/RED MAP (MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR) Detects MAP sensor signal With ignition switch ON (II): about 3 V
At idle: about 1.0 V (depending on engine speed)
20 YEL/BLU VCC2 (SENSOR VOLTAGE) Provides sensor voltage With ignition switch ON (II): about 5 V
With ignition switch OFF: about 0 V
21 YEL/RED VCC1 (SENSOR VOLTAGE) Provides sensor voltage With ignition switch ON (II): about 5 V
With ignition switch OFF: about 0 V
23 BRN/YEL LG2 (LOGIC GROUND) Ground for the PCM circuit Less than 1.0 V at all times
24 BRN/YEL LG1 (LOGIC GROUND) Ground for the PCM circuit Less than 1.0 V at all times
25 WHT/RED SHO2S (SECONDARY HEATED OXYGEN SENSOR (SECONDARY HO2S), SENSOR 2) Detects secondary HO2S (sensor 2) signal With throttle fully opened from idle with fully warmed up engine: about 0.6 V
With throttle quickly closed: below 0.4 V
26 GRN CMP (TDC) (CAMSHAFT SPEED (CMP) SENSOR (TOP DEAD CENTER (TDC) SENSOR)) Detects CMP (TDC) sensor With engine running: pulses
27 BRN IGPLS4 (No. 4 IGNITION COIL PULSE) Drives No. 4 ignition coil With ignition switch ON (II): about 0 V
With engine running: pulses
28 WHT/BLU IGPLS3 (No. 3 IGNITION COIL PULSE) Drives No. 3 ignition coil
29 BLU/RED IGPLS2 (No. 2 IGNITION COIL PULSE) Drives No. 2 ignition coil
30 YEL/GRN IGPLS1 (No. 1 IGNITION COIL PULSE) Drives No. 1 ignition coil
Fig 2: Identifying Connector B (24P) Terminals
G04535991Courtesy of AMERICAN HONDA MOTOR CO., INC.
NOTE: Standard battery voltage is 12 V.
CONNECTOR B (24P) TERMINALS REFERENCE

Terminal number Wire color Terminal name Description Signal
2 YEL INJC4 (No. 4 INJECTOR CONTROL) Drives No. 4 injector With ignition switch ON (II): battery voltage
At idle: duty controlled
3 BLU INJC3 (No. 3 INJECTOR CONTROL) Drives No. 3 injector
4 RED INJC2 (No. 2 INJECTOR CONTROL) Drives No. 2 injector
5 BRN INJC1 (No. 1 INJECTOR CONTROL) Drives No. 1 injector
6 GRN FANC (RADIATOR FAN CONTROL) Drives radiator fan relay With radiator fan running: about 0 V
With radiator fan stopped: battery voltage
7 GRN/WHT HLCLS+ (CVT PULLEY PRESSURE CONTROL VALVE +SIDE) Drives CVT pulley pressure control valve With the ignition switch ON (II): duty controlled
8 RED/WHT ECT (ENGINE COOLANT TEMPERATURE (ECT) SENSOR) Detects ECT sensor signal With the ignition switch ON (II): about 0.1-4.8 V
(depending on engine coolant temperature)
10 WHT/BLU ALTL (ALTERNATOR L SIGNAL) Detects alternator L signal With ignition switch ON (II): about 0 V
With engine running: battery voltage
13 WHT/RED ALTF (ALTERNATOR FR SIGNAL) Detects alternator FR signal With engine running: 0-5 V (depending on electrical load)
16 YEL/GRN SCLS+ (CVT START CLUTCH PRESSURE CONTROL VALVE +SIDE) Detects CVT start clutch pressure control valve With ignition switch ON (II): duty controlled
17 RED/YEL IAT (INTAKE AIR TEMPERATURE (IAT) SENSOR) Detects IAT sensor signal With ignition switch ON (II): about 0.1-4.8 V (depending on intake air temperature)
18 WHT/GRN ALTC (ALTERNATOR CONTROL) Sends alternator control signal With engine running: about 0-5 V (depending on electrical load)
24 BLU/WHT SHLS+ (CVT SPEED CHANGE CONTROL VALVE + SIDE) Drives CVT speed change control valve With ignition switch ON (II): duty controlled