OBD0 Pinouts

EDM PM5/P04 (D15B2), PM6 (D16A9/D16Z5), PW0 (B16A1)

On this page I present a number of OBD0 pinouts known to me. There are small differences between the 4th gen and 5th gen Civic D15B2 engines. The first has the PM5 ECU and the latter one has the P04 ECU. The pinout is based on the P04, small differences in the PM5 are marked between brackets ( – ).

DPFi pinout for the PM5 and P04 ECUs for D15B2 engines. Normal font is 5th gen Civic. Colours and functions between brackets () are 4th gen Civic.

Nomenclature DPFi:
ACC –   A/C relay
ACS –   A/C switch
ALTF –  Alternator switch
CKP –   Crankshaft position, (P)ulse or (M)ass, gives several pulses (~20?) during each cam shaft rotation
ECT –    Engine coolant temperature
FLR –    Fuel relay
IACV – Idle air control valve, controls the 2 wire type IACV valve
IAT –     Intake air temperature
ICM –    Ignition pulses
IGP –    Battery feed, only active when key is turned
INJ –     Injector, AUX for auxilry and MAIN for MAIN injectors, the wires go from 4 to 2 about 30 cm from the ECU
ITAC –   Ignition timing connector, same timing functionality as SCS, but no error code reading (read from LED instead)  
LG –      Ground for battery circuit
MAP –   Manifold absolute pressure
MIL –     Motor indication light, this one gives the control engine light (CEL) signal
PA –     Atmosferic pressure
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
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
TCS –    Tandem valve control solenoid
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

MPFi pinout of PM7 and PW0 ECUs for D16A9 and B16A1 engines for 4th gen Civic and 2nd gen CRX. D16A9 specific pins are in grey, B16A1 specific pins are between brackets (), for D16Z5 see below.

Nomenclature changes for MPFi:
CKP –   Same as for DPFi, however located at a different location
CYP –   Cylinder position, (P)ulse or (M)ass, gives one pulse during each cam shaft rotation
DSCV-  Unknown (probably solenoid  located near IM), found on D16A9 and D16Z5
IMA –    Idle mixture adjustment, found on D16A9, the D16Z5 has ITAC instead
INJ –     Injector, the number refers to the cylinder used (1 is on the side with the belts)
SO2S – Secondary oxygen sensor signal on B16A1
VTM –   Oil pressure switch, only present on B16A1
VTS –    VTEC solenoid, only present on B16A1

A10 connects to a solenoid on B16A1 engines. The function and location of this solenoid are unknown to me. I never had problems leaving this wire unconnected in OBD1 conversions. Beware of mixing up 5th gen DPFi CKP and MPFi CYP wires. They have the same colors, though different functionalities!

About the D16Z5 engines I have some doubts. I do not know for instance if they have the DSCV and PA connections. Pins B20 and C16 need some clarification. In basic the cars without a catalyc converter (D16A9 in this case) have ITAC on C16 and use IMA (it is just a screw on a potentiometer) on B20 for the correct mixture. Cars with catalyc converters (D16Z5 and B16A1 in this case) have ITAC on B20 and use the lambda sensor to monitor the idle mixture.

Any questions and/or remarks send them to me.

Dodo Bizar

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