OBD0 HONDA ECU PINOUT - OEM - 1988-1992
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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) | |
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| 4 | 5 | 6 | 7 | |||
| 8 | 9 | 10 | 11 | |||
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| 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 | |
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| 4 | 5 | 6 | 7 | |||
| 8 | 9 | 10 | 11 | |||
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| Drivers-side round plug C313 - Round Style | ||||
|---|---|---|---|---|
| Pin | Wire Color | Terminal Name | Description | |
| 1 | YEL/BLK | Main Injector | Main Relay | |
| 2 | RED | Main Injector | A5 & A7 | |
| 3 | BLU/YEL | EACV | A11 | |
| 4 | GRN/BLK | Main Relay | ||
| 5 | YEL | AUX Injector | A1 & A3 | |
| 6 | YEL/BLK | AUX Injector | Main Relay | |
| 7 | YEL | Lock-Up Solenoid | (Auto Trans Only) | |
| 8 | ORN | Tandem Valve | B2 | |
| 9 | BLK/YEL | Tandem Valve | 12V+ | |
| 10 | YEL/GRN | FAN Relay | B4 | |
| 11 | WHT | Igniter | B15 | |
| 12 | YEL/WHT | EGR Valve | (Auto Trans Only) | |
| 13 | YEL | EGR Valve | (Auto Trans Only) | |
| 14 | GRN/WHT | (Auto Trans Only) | ||
'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
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| / | 4 | 5 | 6 | ||
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| 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 | |