Just finished swapping an OBD2a b18c5 motor and it's engine harness into a 1993 Honda Civic Hatchback. On the passenger side shock tower there are 3 big connectors where the b18c5 engine harness connects to the stock Civic wiring harness. Everything I've read states that there should be 3 connectors and it's plug and play. Mysteriously there is a 4th one on the engine harness!! See the image below - It's the one labeled and taped up with black tape (I did that; it IS normally used).



The wires are White/red, Blue/red and Red/yellow.

Info that may help: I'm waiting for my ecu but the engine starts with a p28 and triggers no codes while idling for 30 seconds. Appears to run properly.

Thanks for your help.

 

I'd need to double check by looking at my B18C5 harness in my 1992 Civic, but I believe you simply leave the "extra" plug alone and tuck it away.

I've never cared to find out what it's for, but between the ITR having ABS and extra sensors for OBD2 BS I'm sure it's something like that.

I've ran my car like it is for over 4 years with zero CELs or any other issues.

 

Thanks for your help Tom. If you could take a minute to check your car and respond I'd sleep better at night knowing it's not a vital component...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by W.O.T. &raquo;</TD></TR><TR><TD CLASS="quote">Thanks for your help Tom. If you could take a minute to check your car and respond I'd sleep better at night knowing it's not a vital component...</TD></TR></TABLE>

Well I can't check and post until tomorrow since my car's at home today, but yeah I'll double check tonight.

I'm pretty damn sure my plug is basically tucked out of the way. What I'd really like to do is next time we have an ITR at the shop here I'll check to see what the plug actually goes to.

 

i also had one on my obd2 LS. had no effect, and sadly i don;t know what its for. maybe ill disect one of my obd2 harnesses and see.....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WrongWD &raquo;</TD></TR><TR><TD CLASS="quote">i also had one on my obd2 LS. had no effect, and sadly i don;t know what its for. maybe ill disect one of my obd2 harnesses and see.....</TD></TR></TABLE>
Same Here

 

I forget what it's for but I know if you pull the plug out from the end of it the car won't start.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by skunked &raquo;</TD></TR><TR><TD CLASS="quote">I forget what it's for but I know if you pull the plug out from the end of it the car won't start.</TD></TR></TABLE>

Are you sure you are not talking about the diagnostic port that has a "filler" plug in it? My car definately starts.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by W.O.T. &raquo;</TD></TR><TR><TD CLASS="quote">

Are you sure you are not talking about the diagnostic port that has a "filler" plug in it? My car definately starts.</TD></TR></TABLE>

Yep, I was talking about that. It's actually a jumper, my car won't start without it.....(that's what I remember atleast).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by skunked &raquo;</TD></TR><TR><TD CLASS="quote">I forget what it's for but I know if you pull the plug out from the end of it the car won't start.</TD></TR></TABLE>

Perhaps that's only for OBD2 cars maybe?

 

I forgot too, but I believe its either 2nd 02, power steering, or OBD2 smog related...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C5-EH2 &raquo;</TD></TR><TR><TD CLASS="quote">

Perhaps that's only for OBD2 cars maybe?</TD></TR></TABLE>

no mine is OBD1 94 GSR, my buddy is the one who actually told me because it's one of his theft devices (EG hatch).

When my motor is back in I'll have to try it again.

 

Well my plug is empty and my car has started like that since I built it over 4 years ago.

Hmmm...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C5-EH2 &raquo;</TD></TR><TR><TD CLASS="quote">Well my plug is empty and my car has started like that since I built it over 4 years ago.

Hmmm...</TD></TR></TABLE>

Now you have got me wondering. I'll look at my harness tonight and pull the plug.

 

ok just checked a 97 Integra Helm's manual.

Its a little confusing in the manual, but since you described the wire colors the book says that this is plug C103 which the blue/red + wht/red wires are directly connected to the CKF sensor and the red/yellow is related to IAT sensor.


I'm curious...
what other sensor plugs did you leave unplugged besides this C220 plug, CKF, and 2nd 02 sensor?




Modified by Katman at 2:36 PM 10/29/2005

 

Well it just so happens an ITR just came in for some service, so I checked the plug out, and it goes to the EVAP canister - looks like the EVAP pressure sensor.

That little bastard is what causes the check engine code P1456 on OBD2 cars - definately do NOT need it on any OBD1 car seeing as how they lack that EVAP pressure sensor.

 

Woo hoo. Thanks for the detective work guys!