OBD2b Pinouts

EDM P2Y (D15Z6)

On this page some OBD2b shemes from mainly the EDM (Europen Domestic Market) are shown. Some connections are different from car to car. The first scheme is based on the D15Z6 found in most EK3 chassis. Below you will also find the P3X/P3Y found in EJ9 chassis after the facelift with D14Z1 and D14Z2 engines. Also the Honda Logo pinout for the OBD2b P7A ECU of D13B7 (8 valves). The first pinout serves as a general overview with most common connections in black fonts. Others are less important (read: often not occurring in OBD1 cars). Both types of connections are marked grey. The NEP connections marked in red deserves special attention.

Nomenclature:
ACC – A/C clutch relay
ACS – A/C switch
ALTC – Alternator relay, not always present
ALTF – Alternator switch
BKSW – Brake switch, not always present
CKF – Crankshaft speed, Pulse or Mass, gives 12 pulses by LED during each crank shaft rotation
CKP – Crankshaft position, Pulse or Mass, gives several pulses during each cam shaft rotation (20+ pulses)
CYP – Cylinder position, Pulse or Mass, gives 1 pulse during each cam shaft rotation
DLC – Data link connector
ECO – ECONOMO light
ECT – Engine coolant temperature
EGRL – Exhaust gas recirculation lift sensor
ELD – Electric load detection, not always present
ESOL – Exhaust gas recirculation control solenoid
FANC – Radiator fan relay, not always present
FLR – Fuel relay
IACV – Idle air control valve, controls 2 wire type valve
IAT – Intake air temperature
ICM – Ignition firing pulses
IGP – Battery feed, active when key is turned
IMO – Checks IMO code of the key and activates FLR if correct
INJ – Injector, the number refers to the cylinder used (1 is on the side with the belts)
INOCD – Checks IMO code of the key and activates FLR if correct
LG – Grounded shield for CYP, TDC, CKP, CKF and O2S wires
MAP – Manifold absolute pressure
MIL – Motor indication light, provides the blinking light (CEL) signal
NEP – Signal to engine speedometer driven by ECU
PCS – Purge cut-off solenoid
PG – Ground circuits, 1 and 2 are joined and connected to chassis at G101 at the thermostate housing
PO2S – Primary oxygen sensor signal
PSP – Power steering switch, not always present
SCS – Service check connector, short to SG2 to read CEL codes
SG – Sensor circuit ground, 1 is for the MAP circuit, 2 for all other sensors
STS – Starter switch
TDC – Top dead centre, Pulse or Mass, gives 4 pulses during each cam shaft rotation
TPS – Throttle position signal
VBU – Back up battery feed, always hot (unless battery is removed)
VCC – 5V sensor feed, 1 is for the MAP circuit, 2 is for all other sensors
VSS – Vehicle speed sensor
VTS – VTEC solenoid

OBD1 conversions are very straightforward even using only the schemes provided in the pinout section on my site. However the NEP signal needs some attention. In OBD2b this wire is a rpm signal send by the ECU directly towards the rpm gauge in the cockpit. However, all other OBD types provide the gauge with signal from the distributor instead of the ECU (IGR signal). For those other OBD types there are generally 9 wires on the distributor, OBD2b has only 8 wires. The blue one misses on OBD2b. The solution when installing an OBD1 ECU is simple, short the NEP wire to ICM somewhere and the rpm gauge should work.

Many OBD1 ECU’s use a VTM or VTPS (VTEC Pressure Switch) to monitor if there is enough oil pressure to engage VTEC safely. A few OBD1 engines and many OBD2 engines lack this VTM sensor. Not having the physical pressure sensor, but running an ECU that does need it will throw a code 22 engine error for VTEC oil pressue. This can be omitted by splitting the VTS wire and connecting the second end to VTM or VTPS on the ECU. This will let the ECU think there is enough oil pressure. Although preferably you should remove the VTEC oil pressure check from the ECU software if there is no physical sensor. The splitting trick generally works, but has caused me in the past to throw a code 22 once while driving.

Below is another pinout as exactly found on a OBD2b equipped EJ9 chassis. Very similar to ‘normal’ OBD2b:

Nomenclature additions and alterations specific for EJ9 Civis:
IACV N/P – Idle air control valve, controls 3 wire type valve, Negative and Positive
PO2H – Primary oxygen sensor heater control, connects to battery to activate the heater
SO2H – Secondary oxygen sensor heater control, connects to battery to activate the heater
SO2S – Secondary oxygen sensor signal

Below is another pinout as exactly found on a Honda Logo with D13B7 8V. Very similar to ‘normal’ OBD2b and almost exactly the same as the EJ9 version above:

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

Dodo Bizar