OBD1 V6 Pinouts

PR7 (C30A)

On this page you find the NSX PR7 C30A pinout to my best knowledge. Normally I want to verify the colors by checking colors in the real car, however for this one I have relied on workshop manuals and various internet sources. The F-connector is rarely documented on the web, but I got it. Hopefully the clip is shown with the right orientation.

I expect, but cannot guarantee, that the pinout is correct for USDM, EDM and JDM versions. The abbriviations used are those from the workshop manual. In the function list below the pinout I’ll state the more common abbreviations used for Civics etc.

OBD1 pinout for PR7 (C30A) engine found in NSX’s. Note that functions and colors have not been verified and F-connector may be oriented wrong with respect to the clips.

Nomenclature (better known synonyms between parentheses):
ACC – A/C clutch relay
ACGF (ALTF) – Alternator switch
ACP – Accelerator pedal angle sensor
AFS – A/T control unit, A and B
BPS – Chamber volume control solenoid
CLS – M/T only, clutch switch
CRNK (CKP) – Crankshaft position, 1 for A and 2 for B, Pulse or Mass, gives 24 pulses during each cam shaft rotation
CYL (CYP) – Cylinder position pulse, 1 for A and 2 for B, Pulse or Mass, gives 1 pulse during each cam shaft rotation
EACV – Electronic air control valve, controls 2 wire type valve
EGRL – Exhaust gas recirculation lift sensor
ES (EGR) – Exhaust gas recirculation control solenoid
FANCNT (FANC) – Radiator fan high relay
FAS – A/T control unit
FLR – Fuel relay circuit, 1 for main relay, 2 for fuel pump relay
HTCNT (PO2H) – Oxygen sensor heater control, Front or Rear, connects to battery to activate the heater
IG (ICM) – Ignition pulses, the number refers to the cylinder used
IGADJ – Ignition timing adjuster
IGP – Battery feed, active when key is turned, 1 and 2 are joined
INJ – Injector, the number refers to the cylinder used
KS – Knock sensor Front and Rear
LG – Grounded shield, 1 for CYL and CRNK, 2 for KS and O2 wires
NEP – Tacho meter connector
N SW or NP SW – M/T neutral switch or A/T shift position switch
O2 (PO2S) – Primary oxygen sensor signal, Front and Rear
PAOUT – Traction Control
PB (MAP) – Manifold absolute pressure
PCS – Purge cut-off solenoid
PDSW (ACS) – A/C pressure switch
PG – Ground circuits, 1 for G101 and main relay, 2 for G101
SCS – Service check connector, short to SG to read CEL codes
SG – Sensor circuit ground, 1 is for PB, 2 is for all other sensors although both wires are joint
STS – Starter switch
TA (IAT) – Intake air temperature
TCFC – Traction Control
TCINH – Traction Control
TCSTB – Traction Control
TH (TPS) – Throttle position signal
TQOUT – Traction Control
TW (ECT) –    Engine coolant temperature
VBU – Back up battery feed, always hot (unless battery is removed)
VCC – 5V sensor feed, 1 for PB circuit, 2 for all other sensors although both wires are joint
VFP – Voltage fuel pump
VREF – A/T and traction control
VSP (VSS) – Vehicle speed sensor
VTM – Oil pressure switch, Front and Rear
VTS – VTEC solenoid, Front and Rear
WARN (MIL) – Warn or motor indication light, provides the blinking light (CEL) signal

Some extra notes:

This ECU pinout is similar to other pinouts, e.g. for Legend engines from the same era. However some pins are different and the F-connector is not used. There may be an E-connecter for automatic transmission models.

A thing that surprised me is that this type of ECU, while sharing A, B and D connectors, many pin functions and colours and coming from the same years as the 5th gen Civics dont have a port for OBD communications. The typical DLC or TXD/RXD pin is not available to my knowledge for both NSX and Legend alike.

To conclude. I wanted to workout this pinout for fun. It will probably be the least used/visited pinout on my website, but ploughing through the workshop manual is practically the closest I can get to getting hands-on working on a NSX. That said, anyone willing to let me verify wire colors and functioning is always welcome.

Please, send any questions and/or remarks to me.

Dodo Bizar

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