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On this page the OBD1 sheme’s known to me are presented EDM (Europen Domestic Market) style. The biggest difference between EDM and USDM (United States Domestic Market) is the ELD circuit (Electric Load Detection) that misses and the KS (Knock Sensor). Some connections are only found on P28 and P30 ECU’s. Those are marked coloured red. Some connections are different from car to car. Those are marked grey.


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

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 - Unknown function (is there an ECO light on D15Z3?)

ECT - Engine coolant temperature

EGR - Exhaust gas recirculation

EGRL - Unknown function (probably related to EGR)

FANC - Fan relay, for control purposes, not present on all ECU’s

FLR - Fuel relay, 1 is always present, 2 can be ignored

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

INJ - Injector, the number refers to the cylinder used (1 is on the side with the belts)

LG - Ground for battery circuit

MAP - Manifold absolute pressure

MIL - Motor indication light, this one gives the control engine light (CEL) signal

PCS - Control solenoid, this one is for the small black cylindric valve on the back of the IM

PG - Ground for battery circuit

PO2H - Primary oxygen sensor heater, connects with the ground of the car to activate the heater

PO2S - Primary oxygen sensor signal

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

VREF - Unknown function (probably related to wideband oxygen)

VSS - Vehicle speed sensor

VTM - Oil pressure switch, only -but not always- present on VTEC equiped vehicles

VTS - VTEC solenoid, only present on VTEC equiped vehicles

Below I also provided a D15Z3 sheme. Unfortunatly not each function of all pins are known to me. I do know that most question marks are connected to either the EGR (Exhaust Gas Recirculation) and wideband lambda sensor system (Yes this car has a wideband oxygen sensor system normally. However, I do not know the exact possibilities of this sensor). I used the sheme succesfully for a P28 ECU swap once. The wideband lambda wires can be re-used for a normal 4-wire lambda sensor. The VTM pin can be short circuited to the VTS pin to prevent VTEC error codes from the P28 ECU.