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OBD0 Honda ECU Pinout

1988-1991 Civic

1990-1991 Integra

1 3 5 7 11 13 15 17
2 4 6 8 / 12 14 16 18
OBD0 ECU A (18 Pin) C451
Pin Wire Color Terminal Name Description Test
1 BRN INJ1 Injector 1 + 1.5V - 2.5 Ohms
2 BLK PG1 Power Ground (Main Relay), A4
3 RED INJ2 Injector 2 + 1.5V - 2.5 Ohms
4 BLK PG2 Power Ground (Main Relay), A2
5 LT BLU INJ3 Injector 3 + 1.5V - 2.5 Ohms
6 BLU PCS Purge Control Solenoid Coolant Temp > 154F: 12V when activated
7 YEL INJ4 Injector 4 + 1.5V - 2.5 Ohms
8 RED EGR Exhaust Gas Recycling Control Solenoid Valve '88-91 Civic, '90-91 Integra Automatic
8 GRN/WHT VTS (VTEC) Spool Control Solenoid
10 GRN Pressure Regulator Cut-off Solenoid
11 BLU/YEL IACV (EACV)) Idle Air Control Valve 12V to A2, Unplugged 8-15 Ohms
12 GRN/BLK FLR1 Main Relay 8
13 YEL/BLK IGP1 Injector resistor pack and Main Relay Power Main Relay 3
14 GRN/BLK FLR2 Main Relay 8 redundant
15 YEL/BLK IGP2 Injector resistor pack and Main Relay Power redundant
16 BRN/BLK LG2 Logic Ground Less than 1V at all times
17 BLK/YEL EACV (IACV) Idle Air Control Valve Dash fuse #14
18 BLK/RED LG1 Logic Ground Less than 1V at all times
1 3 5 7 9 11 13 15 17 19
2 / / 8 10 12 14 16 18 20
OBD0 ECU B (20 Pin) C452
Pin Wire Color Terminal Name Description Test
1 WHT/GRN VBU Voltage Backup Hazard Fuse under hood
2 BLU/YEL (Integra) TCS Tandem Control Solenoid (Fast Idle)
2 BLU (Civic) DSCV Dashpot Control Solenoid Valve
3 YEL ACC AC Clutch Relay Connect to A18, clutch should click
4 YEL/GRN (Integra) FANC Radiator Fan Control Fan Running: 0V
4 GRN (Civic) PCS Purge Cut-off Solenoid Valve
4 BLU/WHT A/T Control Unit Automatic Integra
5 WHT/YEL ALT C Alternator Control 12 - 0V
5 BLU/BLK VTM VTEC Pressure Switch (B16)
6 GRN/ORN MIL Malfunction Indicator Light CEL On when grounded
7 BLU/WHT ATSP A/T Shift Position Signal 5V to A18
8 BLU/RED ACS + AC Switch 5V to A18
10 ORN CKP P Crank Position + (Distributor) Resistance to C12 350-700 Ohms
11 BLK/GRN Rear Defogger Switch (B16)
12 WHT CKP M Crank Position - (Distributor)
13 BLU/WHT STS Starter Switch Signal to Main Relay 4 Engine cranking: 12V
14 BLU ALT FR Alternator Charging Signal 5V to A18
15 WHT ICM1 Ignition Control Module 10V to A18
16 YEL/RED VSS Vehicle Speed Sensor (Gauge cluster) Ignition on, Front wheels rotating: 0 - 5V cycles
17 WHT ICM2 Ignition Control Module redundant
19 RED/BLU KS Knock Sensor
19 RED PSP SW Power Steering Pressure Switch Turn steering wheel, 12V to A18
19 GRN/RED ELD Electric Load Detector
20 BRN Service Check Signal (SCS) Enables Diagnostic mode Jumpered for Ignition Timing Adjustment
1 3 5 7 9 11 13 15
2 4 6 8 10 12 14 16
OBD0 ECU C (16 Pin) C453
Pin Wire Color Terminal Name Description Test
1 BLU/GRN CYP P Cylinder Position + (Distributor) Resistance to C2 350-700 Ohms
2 BLU/YEL CYP M Cylinder Position - (Distributor)
3 ORN/BLU TDC P Top Dead Center + (Distributor) Resistance to C4 350-700 Ohms
4 WHT/BLU TDC M Top Dead Center - (Distributor)
5 RED/YEL IAT (TA) Intake Air Temperature 5V, Sensor resistance (unplugged) 1-4k Ohms
6 RED/WHT ECT (TW) Engine Coolant Temperature 5V, Sensor resistance (unplugged) 200-400 Ohm
7 RED/BLU TPS Throttle Position Sensor Fully Open: 4.5V, Closed: .3V
8 RED/BLU SO2S 2nd Oxygen Sensor (B16)
9 RED/WHT PA Sensor Atmospheric Pressure (Barometric) Signal 5V
10 GRN/WHT BKSW Brake Switch signal + Brake pressed: 12V
11 WHT MAP + Manifold Absolute Pressure 3V
12 GRN/WHT SG2 Sensor Ground (TPS, IAT) 5V -
13 YEL/WHT VCC2 Sensor Voltage (TPS / PA Sensor) 5V +
14 GRN/WHT SG1 Sensor Ground (MAP) 5V -
15 YEL/RED VCC1 Sensor Voltage (MAP) 5V +
16 WHT PO2S Primary Oxygen Sensor

Strut Tower Plugs

1 2 3 4
5 6 7 8
Passenger-side rectangle plug C211
Pin Wire Color Terminal Name Description
1 BLK/YEL (10awg) IGNITION Ignition 12V (Distributor)
2 BLK/WHT (10awg) STS Cranking 12V
3 WHT/BLU Charging Warning Light Battery Dash Light
4 BLK/YEL x2 Ignition 12V ALT, IACV
5 BLU Engine Speed Gauge Cluster Tachometer
6 YEL/GRN ECT (TW) Gauge Cluster Engine Temp
7 YEL/RED Oil Warning Light Gauge cluster Oil Warning Light
8 BLK PG POWER GROUND Main Relay Grounds (thermostat housing)
1 2 3
4 5 6 7
8 9 10 11
12 13 14
Passenger-side round plug C210
Pin Wire Color Terminal Name Description
1 BLK/RED LG Logic ground to A18
2 BRN/BLK LG Thermostat housing ground to A16
3 WHT O2 Sensor O2 Sensor to C16
4 RED/WHT ECT (TW) Coolant Temp to C6
5 RED/YEL IAT (TA) Intake Air Temperature C5
6 GRN/WHT SG Sensor Ground TW TA TPS (TW, TA, TAS) to C12
7 WHT/YEL ALT C Alternator to B5
8 ORN/BLU TDC P Top dead center to C3
9 YEL/BLU ALT FR Alternator to B14
10 YEL/WHT TPS (TAS) Throttle position sensor to C13
11 RED/BLU TPS (TAS) Throttle position sensor to C7
12 WHT CKP M (CAS) Crank Position - to B12
13 ORN CKP P (CAS) Crank Position + to B10
14 WHT/BLU TDC M Top dead center - to C4

'88 Si

1 2 3
4 5 6
Passenger-side '88 Si only C217
Pin Wire Color Terminal Name Description
1 BLU/GRN CYP P Cylinder position to C1
2 WHT ICM Ignitor to B15 & B17
3 YEL Backup Lights Transmission
4 BLU/YEL CYP M Cyinder position to C2
5 YEL/GRN FANC Radiator fan relay to B4
6 GRN/BLK Backup Lights Transmission

'89-91

1 2 3
4 5 6
Driver's-side '89-91 C313
Pin Wire Color Terminal Name Description
1 BRN INJ 1 Injector 1 to A1
2 RED INJ 2 Injector 2 to A3
3 LT BLU INJ 3 Injector 3 to A5
4 YEL INJ 4 Injector 4 to A7
5 BLU/WHT IACV (EACV) Idle motor to A11 (BLU/YEL)
6 YEL/BLK IGP Main relay to Resistor Pack

Distributor

1 2
/ 4 5 6
7 8
When converting to another OBD generation, IGNORE the wire colors and match the sensors up correctly.
Distributor
Pin Wire Color Terminal Name Description
1 WHT/BLU TDC M C4 Top Dead Center -
2 ORN/BLU TDC P C3 Top Dead Center +
4 WHT CKP M B12 Crank Position -
5 ORN CKP P B10 Crank Position +
6 WHT ICM B15, B17 Ignition Control Module
7 BLU/YEL CYP M C2 Cylinder Position -
8 BLU/GRN CYP P C1 Cylinder Position +
1
2
Distributor
Pin Wire Color Terminal Name Description
1 BLK/YEL IGP (Ignition 12V) Fuse 13, Ignition Switch
2 BLU TACH Engine Speed (RPM) Gauge Cluster