OBD1 Pinouts

EDM/USDM P06 (D15B7), P28 (D16Z6/D16Z9), P30 (B16A2), P1G (D15Z3), EDM D15Z8 and EDM B18C4

On this page a comprehensive set of OBD1 pinouts is shown. The first pinout is a mash-up of all the most important OBD1 ECU pinout functions there are. It is based on ECUs and wire looms that I came accross in various models Civic. I also used multiple workshop manuals to complement information from USDM. It is ment to be a reference guide and it is very likely to identify wires you cannot identify by the stock diagrams for P06/P20/P30 only.

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 and have * in their numbering. Then there are square brackets [ ] as well indicating automatic transmission functions. The parentheses ( ) indicate wires found on cars with LAF sensors (Linear Air Fuel ratio a.k.a. wideband) like D15Z1 and D15Z3. Pins specific to those two engines have *** in their numbering. Some pins I only found in USDM manuals are indicated by ** in the numbering.

For those of you looking for the IAB pin needed for the B18C4 scroll down to the bottom of the page.

That all said, here is the OBD1 big mash-up layout:

Nomenclature (other synonyms encountered between parentheses):
ACC – A/C clutch relay
ACS – A/C switch
ALTC (ACGC) – Alternator relay, not always present
ALTF (ACGF) – Alternator switch
ATD – Automatic Transmission only, shift position for 3 and 4
ATLS – Automatic Transmission only, Lockup control solenoid valve A or B
ATNP – Automatic Transmission only, shift position neutral
BKSW – Brake switch, not always present
CKP (CRNK) – Crankshaft position, Pulse or Mass, gives multiple pulses during each cam shaft rotation (20+ pulses)
CLSW – Some manual transmission models only, clutch switch
CYP (CYL) – Cylinder position, Pulse or Mass, gives 1 pulse during each cam shaft rotation
DLC (TXD/RXD) – Data link connector
ECT (TW) – Engine coolant temperature
EGRL – Exhaust gas recirculation lift sensor
EL (ELD) – Electric load detection
ES (EGR or ESOL) – Exhaust gas recirculation control solenoid
FANC – Radiator fan relay, not always present
FLR – Fuel relay, 1 is usually present, 2 is joint with 1 if present
IACV (EACV) – Idle air control valve, controls 2 wire type valve
IAT (TA) – Intake air temperature
ICM (IGP or IGPLS) – Ignition firing pulses, 1 and 2 are joined if both are present
IGP – Battery feed, active when key is turned, 1 and 2 are joined
INJ – Injector, the number refers to the cylinder number used (1 is on the side with the belts)
IP – Linear air fuel sensor function
LABEL – Linear air fuel sensor function
LG – Grounded shield, for CYP, TDC, CKP and PO2S wires, 1 and 2 are joint
MAP (PB) – Manifold absolute pressure
MIL (WARN) – Motor indication light, provides the blinking light (CEL) signal
PCS – Purge cut-off solenoid
PG – Ground circuits, 1 and 2 are joined and connected to chassis at G101 at the thermostate housing
PO2H (HTCNTL or O2SHTC) – Oxygen sensor heater control, connects to battery to activate the heater
PO2S – Oxygen sensor signal
PSW – Power steering switch
SCS – Service check connector, short to SG2 to read CEL codes
SG – Sensor circuit ground, 1 is for MAP circuit, 2 for all other sensors
SIL – Shift indicator light
SLU – Automatic transmission, inter lock control unit
STS – Starter switch
TDC – Top dead centre, Pulse or Mass, gives 4 pulses during each cam shaft rotation
TPS (TH) – Throttle position signal
VBU – Back up battery feed, always hot (unless battery is removed)
VCC – 5V sensor feed, 1 is for MAP circuit, 2 for all other sensors
VS – Linear air fuel sensor function
VSS (VSP) – Vehicle speed sensor
VTM – Oil pressure switch
VTS – VTEC solenoid, only present on VTEC equiped vehicles

Below I included the MA/MB OBD1 ECU layouts for D15Z8 and B18C4. The connectors and layout are very similar to the common OBD1 ECUs but differ in numbering. B18C4 exclusive is indicated by a single * and D15Z8 exclusive by a double **.

There are two warnings when using MA/MB chassis and wire looms;
1) the A-connector does not fit without modification and
2) the CKF circuitry is not compatible to P06/P28/P30 type ECU’s, therefore remove the CKFP and CKFM pins in that case.

Nomenclature additions and alterations specific for MA/MB Civis:
CKF – Crankshaft speed fluctuation sensor Pulse or Mass
ECONO – Econo indicator light, D15Z8 only
IAB SOL – IAB control solenoid valve
IMOCODE – Immo system
LG – Grounded shield, slightly different compared to ‘normal’, 1 for CYPP, TDCP, CKPP, CKFP and 2 for O2S wire and DLC ground, 1 and 2 are joint at G101 at thermostate housing

Pins not mentioned here are (under an alternative name) in the OBD1 comprehensive list above in this article. The position is always the same in that case, so it should not be hard to cross reference and find it.

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

Dodo Bizar