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Honda OBD2 ECU Pinouts: Your Comprehensive Guide

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Understanding your Honda’s OBD2 ECU pinouts is crucial for diagnostics, repairs, and performance tuning. Whether you’re working on a 96-98 Civic, Del Sol, Integra (OBD2A), or a 99-00 Civic/Integra (OBD2B), knowing the Electronic Control Unit (ECU) pin assignments can save you time and prevent costly mistakes. This guide provides detailed pinout diagrams for both OBD2A and OBD2B Honda ECUs, ensuring you have the information you need at your fingertips.

Honda OBD2A ECU Pinouts (96-98 Civic/Del Sol/Integra)

The OBD2A ECU, common in 1996-1998 Honda Civic, Del Sol, and Integra models, utilizes a multi-connector system. Below are the pinouts for Connectors A, C, and D.

Connector “A” Pinouts

This connector primarily handles injector control, oxygen sensor heater circuits, and various solenoids.

  1. Injector 4 – Yellow
  2. Injector 3 – Blue
  3. Injector 2 – Blue
  4. Injector 1 – Brown
  5. S02SHTC (Secondary O2 Sensor Heater Control) – Black/White
  6. P02SHTC (Primary O2 Sensor Heater Control) – Black/White
  7. ESOL E-EGR (EGR Control Solenoid Valve) Civic ONLY – Color Varies
  8. VTS VTEC Solenoid – Green/Yellow
  9. LG1 (Logic Ground) – Brown/Black
  10. PG1 (Power Ground) – Black
  11. IGP1 Power Source – Yellow/Black
  12. IACV (Idle Air Control Valve) – Black/Blue
  13. PCS (Evap Purge Control Solenoid Valve) – Red
  14. FLR (Fuel Pump Relay) (Civic Green/Yellow)(Integra Green/Blue)
  15. ACC (A/C Controller) – Black/Red
  16. MIL (Malfunction Indicator Light) – Green/Orange
  17. ALTC (Alternator Control) – White/Green
  18. ICM (Ignition Control Module) – Yellow/Green
  19. LG2 (Logic Ground) – Brown/Black
  20. PG2 (Power Ground) – Black
  21. IGP2 (Power Source) – Yellow/Black
  22. FANC (Radiator Fan Control) – Green
  23. 2WBS (Evap Bypass Solenoid Valve) – Blue
  24. VSV (Evap Control Canister Vent Shut Valve) (Civic Light Green/White) (Integra Light Green)
  25. SLU (Brake Lock) A/T Civic ONLY – White/Red
  26. Empty Slot
  27. Empty Slot

Connector “C” Pinouts

Connector C is dedicated to sensor inputs like crankshaft and camshaft position sensors, as well as OBD2 diagnostic signals.

  1. CKF P (CKF Sensor P-side) – Blue/Red
  2. CKF P (CKF Sensor P-side) – Blue
  3. TDC P (TDC Sensor P-side) – Green
  4. CYP P (CYP Sensor P-side) – Yellow
  5. ACS (A/C Switch Signal) – Blue/Red
  6. STS (Starter Signal Switch) (Civic Blue/Orange) (Integra Blue/White)
  7. SCS (Service Check Signal) (Civic Brown) (Integra Brown/White)
  8. K-Line (OBD2 Scan Tool Signal) (Civic Main Relay Ground Black 1) (Integra Green/White)
  9. TMA/FAS (A/T TCM related) (Civic Grey) (Integra Yellow)
  10. VBU (Voltage Backup) – White/Blue
  11. CKF M (CYP Ground) – White/Red
  12. CKP M (CKP Ground) (Civic White) (Integra Blue/Yellow)
  13. TDC M (TDC Ground) (Civic Red) (Integra White/Blue)
  14. CYP M (CYP Ground) (Civic Black) (Integra White)
  15. VTM (VTEC Pressure Switch) – Blue/Black
  16. PSPSW (Power Steering Switch Signal) – Green
  17. ALTF (Alternator FR Signal) – White/Red
  18. VSS (Vehicle Speed Sensor) (Civic Blue/White) (Integra Orange)
  19. AT CHK (Detects TCM Signal Integra ONLY) – Blue
  20. Empty Slot
  21. BARO OUT (Barometric Sensor Output) Integra ONLY – Light Green
  22. Empty Slot
  23. IP+ (HO2S Pump Cell) Civic ONLY – Black
  24. IP VS (HO2S Common) Civic ONLY – Red
  25. VS+ (VS Cell Voltage) Civic ONLY – White
  26. Empty Slot
  27. AFSA (A/T TCM Related) Integra ONLY – Grey
  28. AFSA (A/T TCM Related) Integra ONLY – Green/Blue
  29. ATP/NP/CLSW A/T Park + Neutral or Clutch Switch – (A/T Civic Green), (M/T Civic Red), (A/T Integra Green)
  30. TMB (A/T Related to TCM) Civic ONLY – Pink
  31. Empty Slot

Connector “D” Pinouts

This connector manages various engine sensors like Throttle Position Sensor (TPS), Engine Coolant Temperature (ECT), Manifold Absolute Pressure (MAP), and more.

  1. TPS (Throttle Position Sensor) – Red/Black
  2. ECT (Engine Coolant Temp Sensor) – Red/White
  3. MAP (Manifold Absolute Pressure Sensor) (Civic Red/Green) (Integra White/Yellow)
  4. VCC1 (Sensor Voltage for MAP) (Civic Yellow/Red) (Integra Yellow/White)
  5. BKSW (Brake Switch) – Green/White
  6. KS (Knock Sensor) – Red/Blue
  7. PHO2S (Primary Heated O2 Sensor 1) – White
  8. IAT (Intake Air Temp) – Red/Yellow
  9. EGRL (EGR Valve Lift Sensor) Civic ONLY – White/Black
  10. VCC2 (Sensor Voltage) – Yellow/Blue
  11. SG2 (Sensor Ground) (Civic Green/Black) (Integra Green/Blue)
  12. SG1 (Sensor Ground) – Green/White
  13. SHO2/SG (Secondary Heated O2 Sensor Ground) (D16Y7 Red/Yellow), (D16Y8 Green/Black), (Integra Orange/Blue)
  14. SHO2S (Secondary Heated O2 Sensor 2) (Civic White/Red) (Integra Blue/Red)
  15. PTANK (Fuel Tank Pressure Sensor) – Light Green
  16. EL (ELD) (Electric Load Detector) – Green/Red

Honda OBD2B ECU Pinouts (99-00 Civic/Integra)

The OBD2B ECU is found in 1999-2000 Honda Civic and Integra models. It features a different connector layout compared to OBD2A. Here are the pinouts for Connectors A, B, and C.

Connector “A” Pinouts

Similar to OBD2A, Connector A on OBD2B manages EVAP systems, O2 sensor heaters, and some transmission-related signals.

  1. Empty Slot
  2. Empty Slot
  3. 2WBS (EVAP Bypass Solenoid Valve) – Blue
  4. VSV (EVAP Control Canister Vent Shut Valve) – Light Green/White
  5. CRS (Cruise Control Signal) – Blue/Green
  6. PCS (EVAP Purge Control Solenoid Valve) – Red/Yellow
  7. ATPD (A/T Gear Position Switch) – Yellow
  8. SO2SHTC (Second O2 Sensor Heater Control) – Black/White
  9. ATPNP (A/T Gear Position Switch) – Light Green
  10. SCS (Service Check Signal) – Brown
  11. Empty Slot
  12. Empty Slot
  13. Empty Slot
  14. D4IND (A/T D4 Indicator) – Green/Black
  15. Empty Slot (Civic Plug) Integra FLR (Fuel Pump Relay) – Green/Yellow
  16. Empty Slot (Integra Plug) Civic FLR (Fuel Pump Relay) – Green/Yellow
  17. ACC (A/C Clutch Relay) – Black/Red
  18. MIL (Malfunction Indicator Light) – Green/Orange
  19. NEP (Engine Speed Pulse) – Blue
  20. FANC (Radiator Fan Control) – Green
  21. K-Line (OBD2 Scan Tool Signal) – Blue/Yellow
  22. ATP L (A/T Gear Position Switch) – Blue
  23. SHO2S (Secondary Heated O2 Sensor 2) – White/Red
  24. STS (Started Signal Switch) – Green
  25. Empty Slot
  26. PSPSW (Power Steering Power Switch Signal) – Green
  27. ACS (A/C Switch Signal) – Blue/Red
  28. SLU (A/T Brake Related) – White/Red
  29. P TANK (Fuel Tank Pressure) – Light Green
  30. EL (ELD) (Electrical Load Detector) – Green/Red

Connector “B” Pinouts

Connector B on OBD2B ECUs is responsible for injector control, power and logic grounds, VTEC solenoid, and more.

  1. IGP1 (Power Source) – Yellow/Black
  2. PG1 (Power Ground) – Black
  3. INJ2 (Injector 2) – Red
  4. INJ3 (Injector 3) – Blue
  5. INJ4 (Injector 4) – Yellow
  6. IACVP (IACV Position Side) Civic ONLY – Black/Blue
  7. ES (ESOL) (EGR Control Solenoid Valve) – Red
  8. LS (HLC LSM) (CVT Transmission Related) – Pink/Black
  9. IGP2 (Power Source) – Yellow/Black
  10. PG2 (Power Ground) – Black
  11. INJ1 (Injector 1) – Black
  12. VTS (VTEC Solenoid) – Green/Yellow
  13. ICM (Ignition Control Module) – Yellow/Green
  14. Empty Slot Green/Red
  15. IACVN (IACV Negative Side) Civic ONLY – Orange
  16. IAB (Intake Air Bypass Control Solenoid Valve) GSR ONLY – Color Varies
  17. LS+HLC LSM (A/T CVT Transmission Related) (D16Y7 Red) (D16Y5 Green/White)
  18. SC LSM (CVT Transmission Related) – Pink/Blue
  19. Empty Slot
  20. LG1 (Logic Ground) – Brown/Black
  21. VBU (Voltage Backup) – White/Blue
  22. LG2 (Logic Ground) – Brown/Black
  23. IACV (Idle Air Control Valve) – Black/Blue
  24. Empty Slot
  25. SC LSP (CVT Transmission Related) – Yellow

Connector “C” Pinouts

OBD2B Connector C manages primary O2 sensor heater control, knock sensor, various grounds, and sensor inputs.

  1. PO2SHTC (Primary O2 Sensor Heater Control) – Black/White
  2. ALTC (Alternator Control) – White/Green
  3. KS (Knock Sensor) – Red/Blue
  4. Empty Slot
  5. ALTF (Alternator FR Signal) – White/Red
  6. EGRL (EGR Valve Lift Sensor) – White/Black
  7. SG1 (Sensor Ground, Ground for MAP) – Green/White
  8. CKKP (CKP Sensor P-side) – Blue
  9. CKPM (CKP Sensor M-side) – White
  10. VTM (VTEC Pressure Switch) – Blue/Black
  11. Empty Slot
  12. Empty Slot
  13. Empty Slot
  14. Empty Slot
  15. Empty Slot
  16. PHO2S (Primary Heated O2 Sensor 1) – White
  17. MAP (Manifold Absolute Pressure Sensor) – Red/Green
  18. SG2 (Sensor Ground) – Green/Black
  19. VCC1 (Sensor Voltage for MAP) – Yellow/Red
  20. TDCP (TDC Sensor P-side) – Green
  21. TDCM (TDC Sensor M-side) – Red
  22. CKFP (CKF Sensor P-side) – Blue/Red
  23. VSS (Vehicle Speed Sensor) – Blue/White
  24. Empty Slot
  25. IAT (Intake Air Temp) – Red/Yellow
  26. ECT (Engine Coolant Temp Sensor) – Red/White
  27. TPS (Throttle Position Sensor) – Red/Black
  28. VCC2 (Sensor Voltage) – Yellow/Blue
  29. CYPP (CYP Sensor P-side) – Yellow
  30. CYPM (CYP Sensor M-side) – Black
  31. CKFM (CKF Sensor M-side) – White/Red

Having access to these Honda Obd2 Ecu Pinouts is essential for any serious Honda enthusiast or mechanic. Whether you are diagnosing an engine issue, planning an ECU upgrade, or performing custom wiring, these diagrams provide a reliable reference. Always double-check your specific vehicle’s wiring diagrams for any variations.

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