Matt eg

Hello everyone my name is Matthew any help be really appreciated.
I have a Honda Civic eg3 DX. Was originally carb. I changed the dash loom to a esi interior loom,
my engine is a b18c4 and running b18 engine harness with P28 ECU. Went to calibrate my TPS but had no 5 V reference and when I turned the throttle Volts did not change,
checked the earth and all 3 pins have earths at battery voltage, disconnected and same problem, don't have live to any sensors,
And all pins earthed.
My dash lights work and everything. Havnt tried to start it yet as I'm a bit unsure.
please help

thank you

mk378

The 5 volts comes from the ECU and goes to several sensors.

Reasons it could be missing:
No power to ECU-- (Of course you need to turn the key on for the test.)
Circuit from ECU to sensors incomplete
Circuit shorted to ground.

Matt eg

Thanks for your reply mk378. When I was looking for volts I had ignition on,
you say circuit from ecu to sensors incomplete so broken wires ?
my car dosent have a main relay is that just for fuel pump, mine comes of 12 v feed from ignition barrel and works,
Do you know what gives the ecu power ?

Thanks

Former User

Post pictures of the TPS connector showing the three wire colors. Do the same for the MAP sensor connector. Do any of the MAP sensor connector pins have 5V?

The ECU gets voltage from the main relay.

The main relay gets voltage from fuses 31 and 24 (fuse 12 rather than 24 for Civics from Canada).

Matt eg

Hi guys I have a ej9 so took the main relay from that and tried it on my eg and now works im
getting 5 v reference and managed to calibrate the TPS. Obviously the ecu wasn't being powered up
thank you both for your help really appreciated it



TPS



Map



I'm Pritty sure they are the right way round

Former User

OBD2 engine harness in an OBD1 car?

slomofo

iTrader: (1)

Is that a junk2 throttle body?

Matt eg

Yeah that's what we do in the uk and run P28 ecu and all connects no need for jumper harness.
and no it's a 72mm blox

If you ran obd1 would have to change few things. It's an obd2 engine