The P72 ecu is a very common and widely used unit for either chipped applications, or similar piggyback systems to control the electronic fuel injection in many late model Hondas and Acuras. It’s one of the more integral parts of a Honda motor swap, and like many other Honda parts is interchangeable to other vehicles that share a B16, B17, or B18 motor set.
As part of an emerging category of Pro Street FAQ, we’re compiling ECU and PCM pinouts for the many popular sport compact and muscle cars out there and here’s the P72 in OBDI and OBDII flavors.
OBDI P72 ECU Pinouts.
| A1 | BRN | INJ1 | INJ1 |
| A2 | YEL | INJ4 | INJ4 |
| A3 | RED | INJ2 | INJ2 |
| A4 | GRN/YEL | VTS | VTEC solenoid |
| A5 | BLU | INJ3 | INJ3 |
| A6 | ORN/BLK | PO2SHTC | O2 sensor (heating element) |
| A7 | GRN/BLU | FLR1 | fuel pump |
| A8 | (empty) | ||
| A9 | BLK/BLU | IACV | IAC valve |
| A10 | (empty) | ||
| A11 | (empty) | ||
| A12 | GRN | FANC | engine coolant temp switch |
| A13 | GRN/ORN | MIL | MIL (check engine light) |
| A14 | (empty) | ||
| A15 | BLK/RED | ACC | (a/c compressor clutch) |
| A16 | WHT/GRN | ALT C | alternator |
| A17 | PNK/BLU | IAB | IAB Solenoid |
| A18 | (empty) | ||
| A19 | YEL | (AUTO ONLY) | (a/t trans only) |
| A20 | RED | PCS | EVAP purge control solenoid |
| A21 | YEL/GRN | ICM | ICM |
| A22 | (empty) | ||
| A23 | BLK | PG1 | ground |
| A24 | BLK | PG2 | ground |
| A25 | YEL/BLK | IGP2 | to main relay and to gound for o |
| A26 | BRN/BLK | LG1 | gound |
| B1 | YEL/BLK | IGP2 | to pin A25 |
| B2 | BRN/BLK | LG2 | ground to shields for CYP & TDC |
| B3 | (a/t trans only) | ||
| B4 | (a/t trans only) | ||
| B5 | BLU/RED | ACS | a/c switch |
| B6 | (empty) | ||
| B7 | (a/t trans only) | ||
| B8 | GRN | PSPSW | PSP switch |
| B9 | BLU/WHT | STARTER SIGNAL | starter signal |
| B10 | ORN | VSS | vehicle speed sensor |
| B11 | ORN | CYP P | CYP -P |
| B12 | WHT | CYP M | CYP -M |
| B13 | ORN/BLU | TDC P | TDC -P |
| B14 | WHT/BLU | TDC M | TDC -M |
| B15 | BLU/GRN | CKP P | CKP -P |
| B16 | BLU/YEL | CKP M | CKP -M |
| D1 | WHT/BLU | VBU | Back Up Power |
| D2 | GRN/WHT | BKSW | brake switch |
| D3 | KS | Knock Sensor | |
| D4 | BRN/WHT | SCS | service check connector |
| D5 | (empty) | ||
| D6 | BLU/BLK | VTM | VTEC pressure switch |
| D7 | LT BLU | TXD/RXD | (data link connector) |
| D8 | (empty) | ||
| D9 | WHT/RED | ALT F | alternator |
| D10 | GRN/RED | ELD | electric load detector |
| D11 | RED/BLK | TPS | TPS Signal |
| D12 | YEL/GRN | ||
| D13 | RED/WHT | ECT | ECT sensor |
| D14 | WHT/RED | PHO2S | O2 sensor |
| D15 | RED/YEL | IAT | IAT sensor |
| D16 | WHT/BLK | VREF | VREF |
| D17 | WHT/YEL | MAP | Map Signal |
| D18 | (a/t trans only) | ||
| D19 | YEL/WHT | VCC1 | MAP 5V |
| D20 | YEL/BLU | VCC2 | TPS 5V |
| D21 | GRN/WHT | SG1 | MAP GND |
| D22 | GRN/BLU | SG2 | TPS GND |
OBDII ECU PINOUTS
| Pin Number | OBD-2 P72 ECU |
| A1 | #4 Injector |
| A2 | #3 Injector |
| A3 | #2 Injector |
| A4 | #1 Injector |
| A5 | Second O2 Sensor Heat Control |
| A6 | Primary O2 Sensor Heat Control |
| A7 | – |
| A8 | VTEC Spool Solenoid Valve |
| A9 | Logic Ground (LG1) |
| A10 | Power Ground (PG1) |
| A11 | Power Source (IGP1) |
| A12 | Idle Air Control Valve (IACV) |
| A13 | – |
| A14 | – |
| A15 | Evap. Purge Control Solenoid Valve (PCS) |
| A16 | Fuel Pump Relay (FLR) |
| A17 | A/C Clutch Relay |
| A18 | Check Engine Light (MIL) |
| A19 | Alternator Control (ALTC) |
| A20 | Ignition Control Module (ICM) |
| A21 | – |
| A22 | Logic Ground (LG2) |
| A23 | Power Ground (PG2) |
| A24 | Power Source (IGP2) |
| A25 | Reference Voltage (VREF) |
| A26 | Intake Air Bypass Control Solenoid Valve (IAB) |
| A27 | Radiator Fan Control (FANC) |
| B1 | – |
| B2 | – |
| B3 | – |
| B4 | – |
| B5 | – |
| B6 | – |
| B7 | – |
| B8 | – |
| B9 | – |
| B10 | – |
| B11 | – |
| B12 | – |
| B13 | – |
| B14 | – |
| B15 | – |
| B16 | – |
| B17 | – |
| B18 | – |
| B19 | – |
| B20 | – |
| C1 | CKF Sensor (CKF-P) |
| C2 | CKP Sensor (CKP-P) |
| C3 | TDC Sensor (TDC-P) |
| C4 | CYP Sensor (CYP-P) |
| C5 | A/C Switch (ACS) |
| C6 | Starter Switch Signal (STS) |
| C7 | Service Check & Ignition Timing Connector (SCS) |
| C8 | K-Line |
| C9 | Feedback At Signal (FAS) |
| C10 | Voltage Back Up (VBU) |
| C11 | CKF Sensor (CKF-M) |
| C12 | CKP Sensor (CKP-M) |
| C13 | TDC Sensor (TDC-M) |
| C14 | CYP Sensor (CYP-M) |
| C15 | VTEC Pressure Switch (VTM) |
| C16 | P/S Oil Pressure Switch |
| C17 | Alternator FR Signal (ALTF) |
| C18 | Vehicle Speed Sensor (VSS) |
| C19 | – |
| C20 | – |
| C21 | Barometric Sensor Output Signal |
| D1 | Throttle Postion Sensor (TPS) |
| D2 | Engine Coolant Temp. Sensor (ECT) |
| D3 | MAP Sensor |
| D4 | Sensor Voltage (VCC1) |
| D5 | Brake Switch |
| D6 | Knock Sensor |
| D7 | Primary O2 Sensor |
| D8 | Intake Air Temp. Sensor |
| D9 | – |
| D10 | Sensor Voltage (VCC2) |
| D11 | Sensor Ground (SG2) |
| D12 | Sensor Ground (SG1) |
| D13 | Secondary Heated O2 Sensor Ground |
| D14 | Secondary Heated O2 Sensor |
| D15 | Electric Load Detector (ELD) |
Happy Tuning!
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