Understanding your Honda’s Engine Control Unit (ECU) pinouts is crucial for diagnostics, repairs, and performance tuning. This guide provides a detailed breakdown of OBD2A and OBD2B pinouts, commonly found in Honda vehicles from the mid-1990s to early 2000s. Whether you’re diagnosing a fault code or planning an ECU modification, this pinout reference will help you navigate the connections of your Honda ECU.
OBD2A ECU Pinouts (96-98 CIVIC/DEL SOL/INTEGRA)
The OBD2A system was utilized in Honda Civic, Del Sol, and Integra models manufactured between 1996 and 1998. It consists of three connectors: A, C, and D. Below are the detailed pinouts for each connector.
CONNECTOR “A”
This connector generally handles outputs and controls for various engine components.
| Pin | Signal Description | Wire Color |
|---|---|---|
| 1 | Injector 4 Control | Yellow |
| 2 | Injector 3 Control | Blue |
| 3 | Injector 2 Control | Blue |
| 4 | Injector 1 Control | Brown |
| 5 | Secondary O2 Sensor Heater Control | Black/White |
| 6 | Primary O2 Sensor Heater Control | Black/White |
| 7 | EGR Control Solenoid Valve (Civic ONLY) | ? |
| 8 | VTEC Solenoid Control | Green/Yellow |
| 9 | Logic Ground | Brown/Black |
| 10 | Power Ground | Black |
| 11 | Power Source | Yellow/Black |
| 12 | Idle Air Control Valve Control | Black/Blue |
| 15 | Evap Purge Control Solenoid Valve | Red |
| 16 | Fuel Pump Relay Control | Green/Yellow (Civic), Green/Blue (Integra) |
| 17 | A/C Controller | Black/Red |
| 18 | Malfunction Indicator Light (MIL) | Green/Orange |
| 19 | Alternator Control | White/Green |
| 20 | Ignition Control Module | Yellow/Green |
| 22 | Logic Ground | Brown/Black |
| 23 | Power Ground | Black |
| 24 | Power Source | Yellow/Black |
| 27 | Radiator Fan Control | Green |
| 28 | Evap Bypass Solenoid Valve | Blue |
| 29 | Evap Vent Shut Valve | Light Green/White (Civic), Light Green (Integra) |
| 30 | Brake Lock (A/T Civic ONLY) | White/Red |
| 31 | Empty Slot | |
| 32 | Empty Slot |
CONNECTOR “C”
Connector C is primarily focused on sensor inputs and diagnostic signals.
| Pin | Signal Description | Wire Color |
|---|---|---|
| 1 | Crankshaft Speed Fluctuation Sensor (CKF) P-side | Blue/Red |
| 2 | Crankshaft Speed Fluctuation Sensor (CKF) P-side | Blue |
| 3 | Top Dead Center Sensor (TDC) P-side | Green |
| 4 | Cylinder Position Sensor (CYP) P-side | Yellow |
| 5 | A/C Switch Signal | Blue/Red |
| 6 | Starter Signal Switch | Blue/Orange (Civic), Blue/White (Integra) |
| 7 | Service Check Signal (SCS) | Brown (Civic), Brown/White (Integra) |
| 8 | K-Line (OBD2 Scan Tool Signal) | Black (Civic), Green/White (Integra) |
| 9 | A/T TCM Related | Grey (Civic), Yellow (Integra) |
| 10 | Voltage Backup | White/Blue |
| 11 | Crankshaft Speed Fluctuation Sensor (CKF) M-side | White/Red |
| 12 | Crankshaft Position Sensor (CKP) M-side | White (Civic), Blue/Yellow (Integra) |
| 13 | Top Dead Center Sensor (TDC) M-side | Red (Civic), White/Blue (Integra) |
| 14 | Cylinder Position Sensor (CYP) M-side | Black (Civic), White (Integra) |
| 15 | VTEC Pressure Switch | Blue/Black |
| 16 | Power Steering Switch Signal | Green |
| 17 | Alternator FR Signal | White/Red |
| 18 | Vehicle Speed Sensor (VSS) | Blue/White (Civic), Orange (Integra) |
| 19 | A/T TCM Signal Detection (Integra ONLY) | Blue |
| 20 | Empty Slot | |
| 21 | Barometric Sensor Output (Integra ONLY) | Light Green |
| 22 | Empty Slot | |
| 23 | HO2S Pump Cell (Civic ONLY) | Black |
| 24 | HO2S Common (Civic ONLY) | Red |
| 25 | VS Cell Voltage (Civic ONLY) | White |
| 26 | Empty Slot | |
| 27 | A/T TCM Related (Integra ONLY) | Grey |
| 28 | A/T TCM Related (Integra ONLY) | Green/Blue |
| 29 | A/T Park/Neutral or Clutch Switch | Green (A/T Civic), Red (M/T Civic), Green (A/T Integra) |
| 30 | A/T Related to TCM (Civic ONLY) | Pink |
| 31 | Empty Slot |
CONNECTOR “D”
Connector D is mainly for sensor inputs and voltage references.
| Pin | Signal Description | Wire Color |
|---|---|---|
| 1 | Throttle Position Sensor (TPS) | Red/Black |
| 2 | Engine Coolant Temperature Sensor (ECT) | Red/White |
| 3 | Manifold Absolute Pressure Sensor (MAP) | Red/Green (Civic), White/Yellow (Integra) |
| 4 | Sensor Voltage for MAP (VCC1) | Yellow/Red (Civic), Yellow/White (Integra) |
| 5 | Brake Switch | Green/White |
| 6 | Knock Sensor (KS) | Red/Blue |
| 7 | Primary Heated O2 Sensor 1 (PHO2S) | White |
| 8 | Intake Air Temperature Sensor (IAT) | Red/Yellow |
| 9 | EGR Valve Lift Sensor (EGRL) (Civic ONLY) | White/Black |
| 10 | Sensor Voltage (VCC2) | Yellow/Blue |
| 11 | Sensor Ground (SG2) | Green/Black (Civic), Green/Blue (Integra) |
| 12 | Sensor Ground (SG1) | Green/White |
| 13 | Secondary Heated O2 Sensor Ground (SHO2/SG) | Red/Yellow (D16Y7), Green/Black (D16Y8), Orange/Blue (Integra) |
| 14 | Secondary Heated O2 Sensor 2 (SHO2S) | White/Red (Civic), Blue/Red (Integra) |
| 15 | Fuel Tank Pressure Sensor (PTANK) | Light Green |
| 16 | Electric Load Detector (ELD) | Green/Red |
OBD2B ECU Pinouts (99-00 CIVIC/INTEGRA)
The OBD2B system is found in 1999 and 2000 Honda Civic and Integra models. It also uses multiple connectors, in this case, Connectors A, B, and C. Here are the pinout details for OBD2B.
CONNECTOR “A”
Similar to OBD2A, Connector A in OBD2B handles outputs and controls.
| Pin | Signal Description | Wire Color |
|---|---|---|
| 1 | Empty Slot | |
| 2 | Empty Slot | |
| 3 | EVAP Bypass Solenoid Valve (2WBS) | Blue |
| 4 | EVAP Control Canister Vent Shut Valve (VSV) | Light Green/White |
| 5 | Cruise Control Signal (CRS) | Blue/Green |
| 6 | EVAP Purge Control Solenoid Valve (PCS) | Red/Yellow |
| 7 | A/T Gear Position Switch (ATPD) | Yellow |
| 8 | Secondary O2 Sensor Heater Control (SO2SHTC) | Black/White |
| 9 | A/T Gear Position Switch (ATPNP) | Light Green |
| 10 | Service Check Signal (SCS) | Brown |
| 11 | Empty Slot | |
| 12 | Empty Slot | |
| 13 | Empty Slot | |
| 14 | A/T D4 Indicator (D4IND) | Green/Black |
| 15 | Empty Slot (Civic Plug), Fuel Pump Relay (FLR) (Integra Plug) | Green/Yellow |
| 16 | Empty Slot (Integra Plug), Fuel Pump Relay (FLR) (Civic Plug) | Green/Yellow |
| 17 | A/C Clutch Relay (ACC) | Black/Red |
| 18 | Malfunction Indicator Light (MIL) | Green/Orange |
| 19 | Engine Speed Pulse (NEP) | Blue |
| 20 | Radiator Fan Control (FANC) | Green |
| 21 | K-Line (OBD2 Scan Tool Signal) | Blue/Yellow |
| 22 | A/T Gear Position Switch (ATPL) | Blue |
| 23 | Secondary Heated O2 Sensor 2 (SHO2S) | White/Red |
| 24 | Starter Signal Switch (STS) | Green |
| 25 | Empty Slot | |
| 26 | Power Steering Power Switch Signal (PSPSW) | Green |
| 27 | A/C Switch Signal (ACS) | Blue/Red |
| 28 | A/T Brake Related (SLU) | White/Red |
| 29 | Fuel Tank Pressure (P TANK) | Light Green |
| 30 | Electrical Load Detector (ELD) | Green/Red |
CONNECTOR “B”
OBD2B Connector B is responsible for power, grounds, and injector controls.
| Pin | Signal Description | Wire Color |
|---|---|---|
| 1 | Power Source (IGP1) | Yellow/Black |
| 2 | Power Ground (PG1) | Black |
| 3 | Injector 2 Control (INJ2) | Red |
| 4 | Injector 3 Control (INJ3) | Blue |
| 5 | Injector 4 Control (INJ4) | Yellow |
| 6 | IACV Position Side (IACVP) (Civic ONLY) | Black/Blue |
| 7 | EGR Control Solenoid Valve (ESOL) (ES) | Red |
| 8 | HLC LSM (CVT Transmission Related) (LS) | Pink/Black |
| 9 | Power Source (IGP2) | Yellow/Black |
| 10 | Power Ground (PG2) | Black |
| 11 | Injector 1 Control (INJ1) | Black |
| 12 | VTEC Solenoid (VTS) | Green/Yellow |
| 13 | Ignition Control Module (ICM) | Yellow/Green |
| 14 | Empty Slot | Green/Red |
| 15 | IACV Negative Side (IACVN) (Civic ONLY) | Orange |
| 16 | Intake Air Bypass Control Solenoid (IAB) (GSR ONLY) | ? |
| 17 | HLC LSM+ (A/T CVT Transmission Related) | Red (D16Y7), Green/White (D16Y5) |
| 18 | SC LSM (CVT Transmission Related) | Pink/Blue |
| 19 | Empty Slot | |
| 20 | Logic Ground (LG1) | Brown/Black |
| 21 | Voltage Backup (VBU) | White/Blue |
| 22 | Logic Ground (LG2) | Brown/Black |
| 23 | Idle Air Control Valve (IACV) | Black/Blue |
| 24 | Empty Slot | |
| 25 | SC LSP (CVT Transmission Related) | Yellow |
CONNECTOR “C”
Connector C in OBD2B, like OBD2A, is used for sensor inputs and alternator control.
| Pin | Signal Description | Wire Color |
|---|---|---|
| 1 | Primary O2 Sensor Heater Control (PO2SHTC) | Black/White |
| 2 | Alternator Control (ALTC) | White/Green |
| 3 | Knock Sensor (KS) | Red/Blue |
| 4 | Empty Slot | |
| 5 | Alternator FR Signal (ALTF) | White/Red |
| 6 | EGR Valve Lift Sensor (EGRL) | White/Black |
| 7 | Sensor Ground, Ground for MAP (SG1) | Green/White |
| 8 | Crankshaft Position Sensor P-side (CKKP) | Blue |
| 9 | Crankshaft Position Sensor M-side (CKPM) | White |
| 10 | VTEC Pressure Switch (VTM) | Blue/Black |
| 11 | Empty Slot | |
| 12 | Empty Slot | |
| 13 | Empty Slot | |
| 14 | Empty Slot | |
| 15 | Empty Slot | |
| 16 | Primary Heated O2 Sensor 1 (PHO2S) | White |
| 17 | Manifold Absolute Pressure Sensor (MAP) | Red/Green |
| 18 | Sensor Ground (SG2) | Green/Black |
| 19 | Sensor Voltage for MAP (VCC1) | Yellow/Red |
| 20 | Top Dead Center Sensor P-side (TDCP) | Green |
| 21 | Top Dead Center Sensor M-side (TDCM) | Red |
| 22 | Crankshaft Speed Fluctuation Sensor P-side (CKFP) | Blue/Red |
| 23 | Vehicle Speed Sensor (VSS) | Blue/White |
| 24 | Empty Slot | |
| 25 | Intake Air Temperature Sensor (IAT) | Red/Yellow |
| 26 | Engine Coolant Temperature Sensor (ECT) | Red/White |
| 27 | Throttle Position Sensor (TPS) | Red/Black |
| 28 | Sensor Voltage (VCC2) | Yellow/Blue |
| 29 | Cylinder Position Sensor P-side (CYPP) | Yellow |
| 30 | Cylinder Position Sensor M-side (CYPM) | Black |
| 31 | Crankshaft Speed Fluctuation Sensor M-side (CKFM) | White/Red |
Disclaimer: This pinout information is for reference only. Always consult the official Honda service manual for your specific vehicle model and year to ensure accuracy. Incorrect wiring can damage your ECU and vehicle systems.
Recommended Performance Parts (OBD2A/2B Compatible)
For enthusiasts looking to enhance the performance of their OBD2A/2B Honda vehicles, consider these recommended upgrades:
- OBD 2A Jumper: For converting to OBD1 for tuning flexibility.
- OBD 2B Jumper: For OBD2B to OBD1 conversion.
- Wideband O2 Sensor Kit: Essential for accurate air/fuel ratio monitoring.
- E-Boost Controller: For precise boost control in turbocharged applications.
- MAP Sensor: Upgrade for higher boost levels.
- Pressure Sensor: For monitoring various pressures in your engine.
- ECU Socket Kit: For chip tuning and ECU modification.
- Boost Gauge: To monitor boost levels.
- ECU Chip: EEPROM chips for custom ECU tuning.
- Fuel Pump: Upgraded fuel pump for higher horsepower builds.
- Injectors: High-performance fuel injectors for increased fuel flow.
- Turbocharger: For forced induction performance upgrades.
