OBD2b Pinouts

EDM P2Y (D15Z6)

On this page the OBD2b sheme from the EDM (Europen Domestic Market) D15Z6 also known as the 115 bhp VTEC-E is shown. Some connections are different from car to car. Others are less important (read: not occurring in OBD1 cars). Both types of connections are marked grey. The NEP connections marked in red deserves special attention.

Common OBD2b pinout. For example used on P2Y ECU for D15Z6 engine.

Nomenclature:
ACC –   A/C relay
ACS –   A/C switch
ALTC –  Alternator relay, for control purposes, not present on all ECU’s
ALTF –  Alternator switch
BKSW- Brake switch, for control purposes, not present on all ECU’s
CKF –   Crankshaft speed, (P)ulse or (M)ass, gives 12 pulses by LED during each crank shaft rotation
CKP –   Crankshaft position, (P)ulse or (M)ass, gives several pulses (~20?) during each cam shaft rotation
CYP –   Cylinder position, (P)ulse or (M)ass, gives one pulse during each cam shaft rotation
DLC –    Diagnostic connector, communication signal to the 3 wire connector next to the SCS connector
ECO –   ECONOMO light
ECT –    Engine coolant temperature
EGRL – Unknown function (probably related to EGR)
ELD –    Electric load detection, not present on all ECU’s
ESOL – Unknown function (probably OBD1 EGR)
FANC – Fan relay, for control purposes, not present on all ECU’s
FLR –    Fuel relay
IACV – Idle air control valve, controls the 2 wire type IACV valve
IAT –     Intake air temperature
ICM –    Ignition pulses, 1 is always present, 2 can be ignored
IGP –    Battery feed, only 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 –      Ground for battery circuit
MAP –   Manifold absolute pressure
MIL –     Motor indication light, this one gives the control engine light (CEL) signal
NEP –   Signal to engine speedometer
PCS –   Control solenoid, this one is for the small black cylindric valve on the back of the IM
PG –     Ground for battery circuit
PO2S – Primary oxygen sensor signal
PSP. –  Power steering switch, not present on all ECU’s
SCS –   Service connector switch, checks if the SCS connector is hot wired (for reading engine error codes)
SG –     Ground for 5V circuit, 1 is for the MAP sensor, 2 is for the other sensors
STS –    Starter switch
TDC –    Top dead centre, (P)ulse or (M)ass, gives four pulses during each cam shaft rotation
TPS –    Throttle position signal
VBU –   Back up battery feed, always active (unless battery is removed)
VCC –   5V feed, 1 is for the MAP sensor, 2 is for the 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. 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.

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

Dodo Bizar

5 replies on “OBD2b Pinouts”

Hi, first of all I’d like to say that you are a God of D series 😉
Question: is the pinout on D15Z8 the same? If not, what are the differences?

Thnx Evan, I may get back to this question later, but isn’t the D15Z8 always a OBD1 similar type ECU? ECU code P9L to be precise. I actually got hold of the pinouts of this engine just days ago while having owned a Civic with stock D15Z8 for years… Two tips, 1) if it is the P9L and you want to run it on P06/P28/P30 ECU: the A-plug doesn’t fit unless you remove two little pieces of plastic from the connector (you’ll see) and 2) remove D3 and D14 pins from the ecu (edit D5 and D6 in classic OBD1 notation, see below). Those are for the CKF sensor and will ruin the lambda control on ‘real’ OBD1 ECU’s if those wires/CKF sensor are kept.

Auch, when I said remove D3 and D14 in the other reply, that is according to the tranpsposed numbering Honda used for their ECU’s after ~1996. So in ‘classic’ OBD1 numbering it is D5 and D6 that need to be removed. (so third couple of pins from the left on the D-connector). I’ll get the pinouts sorted in the OBD1 section soon.

Hi Kevin, the above OBD2b scheme is already from a 2-wire IACV car.

A 3-wire IACV would have had [B6 – IACV P] and [B15 IACV – N]. A 3-wire IACV car does not have [B23 – IACV]. In that case I would move the B6 to B23 and have B15 deleted. Often with wire harnesses both B6 and B23 are connected together.

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